www.pudn.com > USB_Complete_Source_Code.zip > usbhidio.asm
;Filename: usbhidio.asm
;Version: 1.3
;Date: 11/5/99
;Copyright 1999 by Jan Axelson (jan@lvr.com)
;
;Chip: Cypress Semiconductor CY7C63001 USB Microcontroller
;Assembler: cyasm.exe
;Purpose: demonstrates USB communications with an HID-class device
;Description:
;Handles all required standard USB and HID-class requests.
;Receives data from the host in output reports
;using interrupt transfers on Endpoint 1.
;Sends data to the host in input reports
;using control transfers on Endpoint 0.
;(The chip doesn't support OUT transfers on Endpoint 1.)
;I used Cypress Semiconductor's js50.asm joystick example code as a base
;in creating this program.
;The companion host software is the Visual-Basic project usbhidio.vbp.
;For more information, visit Lakeview Research at http://www.lvr.com .
;Send comments, bug reports, etc. to jan@lvr.com .
;Changes:
;V1.3: 11/20/99
;The length of the string descriptors is now correct.
;(Thanks, John Hyde)
;Changed the control_read routine to prevent error when sending a
;multiple of 8 bytes.
;(Thanks, Dave Wright)
;V1.2:
;added watchdog resets in wait loops,
;took out the watchdog reset in the 1-msec. timer ISR.
;V1.1:
;Clears the watchdog only in the main routine
;(so the watchdog will detect if the main routine crashes).
;Additions to the comments.
;V1.0:
;Clears the Watchdog timer on 1-msec. interrupt.
;(Not needed on the development board, but needed for stand-alone.)
;The Endpoint 1 ISR now sets bit 7 of Endpoint 1 TX config to 1.
;(The bit is cleared on EP1 interrupt.)
;======================================================================
;assembler directives (equates)
;======================================================================
;----------------------------------------------------------------------
;I/O registers
;----------------------------------------------------------------------
;I/O ports
Port0_Data: equ 00h ; GPIO data port 0
Port1_Data: equ 01h ; GPIO data port 1
Port0_Interrupt: equ 04h ; Interrupt enable for port 0
Port1_Interrupt: equ 05h ; Interrupt enable for port 1
Port0_Pullup: equ 08h ; Pullup resistor control for port 0
Port1_Pullup: equ 09h ; Pullup resistor control for port 1
;USB ports
USB_EP0_TX_Config: equ 10h ; USB EP0 transmit configuration
USB_EP1_TX_Config: equ 11h ; USB EP1 transmit configuration
USB_Device_Address: equ 12h ; USB device address assigned by host
USB_Status_Control: equ 13h ; USB status and control register
USB_EP0_RX_Status: equ 14h ; USB EP0 receive status
;Control ports
Global_Interrupt: equ 20h ; Global interrupt enable
Watchdog: equ 21h ; clear watchdog Timer
Timer: equ 23h ; free-running Timer
;GPIO Isink registers
Port0_Isink: equ 30h
Port0_Isink0: equ 30h
Port0_Isink1: equ 31h
Port0_Isink2: equ 32h
Port0_Isink3: equ 33h
Port0_Isink4: equ 34h
Port0_Isink5: equ 35h
Port0_Isink6: equ 36h
Port0_Isink7: equ 37h
Port1_Isink: equ 38h
Port1_Isink0: equ 38h
Port1_Isink1: equ 39h
Port1_Isink2: equ 3Ah
Port1_Isink3: equ 3Bh
;Control port
Status_Control: equ FFh
;----------------------------------------------------------------------
;Register bit values
;----------------------------------------------------------------------
;CPU Status and Control (Status_Control)
RunBit: equ 1h ; CPU Run bit
USBReset: equ 20h ; USB Bus Reset bit
WatchDogReset: equ 40h ; Watchdog Reset bit
; USB EP1 transmit configuration (USB_EP1_TX_Config)
DataToggle: equ 40h ; Data 0/1 bit
DISABLE_REMOTE_WAKEUP: equ 0 ; bit[1] = 0
ENABLE_REMOTE_WAKEUP: equ 2 ; bit[1] = 1
;----------------------------------------------------------------------
;Interrupt masks
;----------------------------------------------------------------------
;The timer-only mask enables the 1-millisecond timer interrupt.
TIMER_ONLY: equ 4h
;The enumerate mask enables the following interrupts:
;1-millisecond timer, USB Endpoint 0
ENUMERATE_MASK: equ 0Ch
;The runtime mask enables the following interrupts:
;1-millisecond timer, USB Endpoint 0, USB Endpoint 1, GPIO
RUNTIME_MASK: equ 5Ch
;----------------------------------------------------------------------
; USB Constants
; from the USB Spec v1.1
;----------------------------------------------------------------------
;standard request codes
get_status: equ 0
clear_feature: equ 1
set_feature: equ 3
set_address: equ 5
get_descriptor: equ 6
set_descriptor: equ 7
get_configuration: equ 8
set_configuration: equ 9
get_interface: equ 10
set_interface: equ 11
synch_frame: equ 12
; standard descriptor types
device: equ 1
configuration: equ 2
string: equ 3
interface: equ 4
endpoint: equ 5
; standard feature selectors
endpoint_stalled: equ 0 ; recipient endpoint
device_remote_wakeup: equ 1 ; recipient device
;----------------------------------------------------------------------
;HID-class descriptors
;from HID Class Definition v1.1 Draft
;----------------------------------------------------------------------
;Class-specific descriptor types from section 7.1 Standard Requests
HID: equ 21h
report: equ 22h
physical: equ 23h
;Class-specific request codes from section 7.2 Class Specific Requests
get_report: equ 1
get_idle: equ 2
get_protocol: equ 3
set_report: equ 9
set_idle: equ 10
set_protocol: equ 11
;----------------------------------------------------------------------
;USB buffer bytes
;----------------------------------------------------------------------
;Control Endpoint 0 buffer
Endpoint_0: equ 70h ; control endpoint
Endpoint0_Byte0: equ 70h ; Endpoint 0, byte 0
Endpoint0_Byte1: equ 71h ; Endpoint 0 byte 1
Endpoint0_Byte2: equ 72h ; Endpoint 0 byte 2
Endpoint0_Byte3: equ 73h ; Endpoint 0 byte 3
Endpoint0_Byte4: equ 74h ; Endpoint 0 byte 4
Endpoint0_Byte5: equ 75h ; Endpoint 0 byte 5
Endpoint0_Byte6: equ 76h ; Endpoint 0 byte 6
Endpoint0_Byte7: equ 77h ; Endpoint 0 byte 7
;Endpoint 0 SETUP packet bytes
bmRequestType: equ 70h
bRequest: equ 71h
wValue: equ 72h ; default wValue (8 bits)
wValueHi: equ 73h
wIndex: equ 74h ; default wIndex (8 bits)
wIndexHi: equ 75h
wLength: equ 76h ; default wLength (8 bits)
wLengthHi: equ 77h
;Endpoint 1 buffer
endpoint_1: equ 78h
Endpoint1_Byte0: equ 78h ; Endpoint 1, byte 0
Endpoint1_Byte1: equ 79h ; Endpoint 1 byte 1
Endpoint1_Byte2: equ 7Ah ; Endpoint 1 byte 2
Endpoint1_Byte3: equ 7Bh ; Endpoint 1 byte 3
Endpoint1_Byte4: equ 7Ch ; Endpoint 1 byte 4
Endpoint1_Byte5: equ 7Dh ; Endpoint 1 byte 5
Endpoint1_Byte6: equ 7Eh ; Endpoint 1 byte 6
Endpoint1_Byte7: equ 7Fh ; Endpoint 1 byte 7
;----------------------------------------------------------------------
; Variables stored in data memory
;----------------------------------------------------------------------
;USB status
remote_wakeup_status: equ 30h ;0=disabled, 2-enabled
configuration_status: equ 31h ;0=unconfigured, 1=configured
;idle_status: equ 33h ;support SetIdle and GetIdle
protocol_status: equ 34h ;0=boot protocol, 1=report protocol
;Other variables:
suspend_counter: equ 35h ;number of idle bus milliseconds
loop_temp: equ 37h ;temporary loop variable
start_send: equ 32h ;0=false, 1=true
;Received data:
Data_Byte0: equ 38h
Data_Byte1: equ 39h
Data_Byte2: equ 3Ah
Data_Byte3: equ 3Bh
Data_Byte4: equ 3Ch
Data_Byte5: equ 3Dh
Data_Byte6: equ 3Eh
Data_Byte7: equ 3Fh
temp: equ 25h
start_time: equ 21h
testbit: equ 22h
interrupt_mask: equ 20h
endp0_data_toggle: equ 23h
loop_counter: equ 24h
data_start: equ 27h
data_count: equ 28h
endpoint_stall: equ 29h
;======================================================================
;interrupt vectors
;======================================================================
org 00h ; Reset vector; begin here after a reset.
jmp Reset
org 02h ; 128-microsecond interrupt
jmp DoNothing_ISR
org 04h ; 1024-millisecond interrupt
jmp One_mSec_ISR
org 06h ; Endpoint 0 interrupt
jmp USB_EP0_ISR
org 08h ; Endpoint 1 interrupt
jmp USB_EP1_ISR
org 0Ah ; reserved interrupt
jmp Reset
org 0Ch ; general purpose I/O interrupt
jmp GPIO_ISR ; not used
org 0Eh ; Wakeup_ISR or resume interrupt
jmp DoNothing_ISR ; not used
ORG 10h
;======================================================================
;Interrupt routines
;======================================================================
;----------------------------------------------------------------------
; 128-microsecond interrupt, Cext
; Unused. If this interrupt occurs, just push the accumulator (because
; ipret pops it) and re-enable the interrupts.
;----------------------------------------------------------------------
DoNothing_ISR:
push A
;Enable interrupts and return
mov A,[interrupt_mask]
ipret Global_Interrupt
;----------------------------------------------------------------------
; 1-millisecond interrupt
; Check to see if the chip is in suspend mode and take appropriate action.
; Copy values to Endpoint 1's buffer for sending.
;----------------------------------------------------------------------
One_mSec_ISR:
push A
iowr Watchdog
;Find out if enumeration is complete.
;If enumerating is in progress, loop_temp = 0.
mov A, [loop_temp]
cmp A, 0h
;If enumeration is still in progress, jump.
jz not_main
;Enumeration has ended, so decrement the loop counter
;(so it no longer = 0).
dec [loop_temp]
not_main:
;Check for bus activity.
iord USB_Status_Control
and A, 01h
cmp A,0h
;If no bus activity, increment the suspend counter.
jz Inc_counter
;If bus activity detected, clear the bus-activity bit,
iord USB_Status_Control
and A, 0FEh
iowr USB_Status_Control
;and clear the suspend counter.
mov A, 0h
mov [suspend_counter], A
jmp Suspend_end
Inc_counter:
;Keep track of the amount of time with no bus activity.
inc [suspend_counter]
;Get the number of milliseconds the bus has been idle.
mov A, [suspend_counter]
;Has it been 3 milliseconds?
cmp A, 03h
;If no, there's nothing else to do.
jnz Suspend_end
;If yes, put the chip in Suspend mode.
;Clear the Suspend counter.
mov A, 0h
mov [suspend_counter], A
;Enable pullups on Port 1; disable the output DAC.
mov A, 0h
iowr Port1_Pullup
mov A, 0ffh
iowr Port1_Data
;Set the Suspend bit.
iord Status_Control
or A, 08h
iowr Status_Control
;The chip is now in Suspend mode.
;On exiting Suspend mode, the chip will begin
;executing instructions here:
nop
;Disable pullups on Port 1. Enable the output DAC.
mov A, 0ffh
iowr Port1_Pullup
mov A, 0h
iowr Port1_Data
Suspend_end:
;Is endpoint 1 enabled?
iord USB_EP1_TX_Config
cmp A,0
;If no, do nothing.
jz Select
;If yes, is start_send = 1?
;(Start_send adds a short delay after enumeration.)
mov A, [start_send]
cmp A, 01h
;If no, do nothing
jnz Select
;If yes, send data:
jmp send_value
send_value:
;Copies values from RAM into Endpoint 1's buffer
;and enables sending the bytes on the next poll.
;disable Endpoint 1 interrupts
mov A,[interrupt_mask]
and A, EFh
mov [interrupt_mask],A
iowr Global_Interrupt
;Copy values from RAM to Endpoint 1's buffer for transmitting to the host.
;Two bytes:
mov A, [Data_Byte0]
mov [Endpoint1_Byte0], A
mov A, [Data_Byte1]
mov [Endpoint1_Byte1], A
;Add more bytes if the report format specifies it:
; mov A, [Data_Byte2]
; mov [Endpoint1_Byte2], A
; mov A, [Data_Byte3]
; mov [Endpoint1_Byte3], A
; mov A, [Data_Byte4]
; mov [Endpoint1_Byte4], A
; mov A, [Data_Byte5]
; mov [Endpoint1_Byte5], A
; mov A, [Data_Byte6]
; mov [Endpoint1_Byte6], A
; mov A, [Data_Byte7]
; mov [Endpoint1_Byte7], A
;Other things to try:
;Set the value at Port 0 to equal byte 0 in Endpoint 1's buffer:
; iord Port0_Data
; mov [Endpoint1_Byte0], A
;Or set a value here and copy to Endpoint 1's buffer, byte 1:
; mov A, A5h
; mov [Endpoint1_Byte1], A
;Configure Endpoint 1's transmit register
;so that the bytes will transmit on the next poll.
iord USB_EP1_TX_Config
;Don't change the Data 0/1 bit.
and A,40h
;Set bits 4 and 7 to 1 enable transmitting.
;The low nibble is the number of data bytes (2).
or A,92h
iowr USB_EP1_TX_Config
Select:
;Enable Endpoint 1 interrupts.
mov A,[interrupt_mask]
or A, 10h
mov [interrupt_mask],A
ipret Global_Interrupt
;----------------------------------------------------------------------
;GPIO interrupt
;Can be configured to trigger when a port bit toggles.
;Unused here.
;----------------------------------------------------------------------
GPIO_ISR:
push A
push X
pop X
mov [interrupt_mask],A
ipret Global_Interrupt
;----------------------------------------------------------------------
;Endpoint 1 ISR
;Endpoint 1 can do IN (device to host) transfers only.
;This interrupt triggers when the host acknowledges
;receiving data from Endpoint 1.
;The ISR toggles the data 0/1 bit for the next transaction and
;sets the EnableRespondToIN bit so the chip will respond to the
;next poll of the endpoint.
;----------------------------------------------------------------------
USB_EP1_ISR:
push A
;Toggle the data 0/1 bit so it's correct for the next transaction.
iord USB_EP1_TX_Config
xor A,40h
;The interrupt clears the EnableRespondToIN bit (bit 7) in the TX Config.
;Set this bit to 1 so data will go out on the next poll.
;This will ensure that a ReadFile API call in a Windows application
;won't hang, waiting for the device to send something.
or A, 92h
iowr USB_EP1_TX_Config
;Enable interrupts and return.
mov A, [interrupt_mask]
ipret Global_Interrupt
;----------------------------------------------------------------------
; Reset processing
; Triggers on Reset or "reserved" interrupt.
;To be safe, initialize everything.
;----------------------------------------------------------------------
Reset:
;Place the data stack pointer at the lowest address of Endpoint 0's buffer.
;This keeps the stack from writing over the USB buffers.
;The USB buffers are in high RAM;
;the data stack pointer pre-decrements on a Push instruction.
mov A, Endpoint_0
swap A, dsp
;Initialize to FFh
mov A, 0ffh
iowr Port0_Data ; output ones to port 0
iowr Port1_Pullup ; disable port 1 pullups
; select rising edge interrupts
iowr Port1_Isink0 ; maximum isink current Port1 bit 0
iowr Port1_Isink1 ; maximum isink current Port1 bit 1
iowr Port1_Isink2 ; maximum isink current Port1 bit 2
iowr Port1_Isink3 ; maximum isink current Port1 bit 3
;Initialize to 00h
mov A, 0h
iowr Port1_Data ; output zeros to port 1
iowr Port0_Interrupt ; disable port 0 interrupts
iowr Port0_Pullup ; enable port 0 pullups
iowr Port0_Isink0 ; minimum sink current Port0 bit 0
iowr Port0_Isink1 ; minimum sink current Port0 bit 1
iowr Port0_Isink2 ; minimum sink current Port0 bit 2
iowr Port0_Isink3 ; minimum sink current Port0 bit 3
iowr Port0_Isink4 ; minimum sink current Port0 bit 4
iowr Port0_Isink5 ; minimum sink current Port0 bit 5
iowr Port0_Isink6 ; minimum sink current Port0 bit 6
iowr Port0_Isink7 ; minimum sink current Port0 bit 7
mov [Endpoint1_Byte0],A
mov [Endpoint1_Byte1],A
mov [Endpoint1_Byte2],A
mov [endpoint_stall], A
mov [remote_wakeup_status], A
mov [configuration_status], A
mov [loop_temp], A
mov [start_send], A
iowr Watchdog ; clear watchdog timer
;Initialize values to transmit at Endpoint 1.
; mov A, A5h
; mov [Data_Byte0], A
; mov A, F0h
; mov [Data_Byte1], A
;Enable Port 1, bit 0 interrupts.
; mov A, 01h
; iowr Port1_Interrupt
;
;Test what kind of reset occurred: bus or watchdog?
iord Status_Control
;Was it a bus reset?
and A, USBReset
;If yes, jump to handle it.
jnz BusReset
iord Status_Control
;Was it a watchdog reset?
and A, WatchDogReset
;If no, continue to wait for a bus reset
jz suspendReset
;
;Watchog reset:
;A watchdog reset means that the watchdog timer
;wasn't cleared for 8.192 milliseconds.
;Wait for a bus reset to bring the system alive again.
;Enable 1-millisecond interrupt only
mov A, TIMER_ONLY
mov [interrupt_mask],A
iowr Global_Interrupt
;Wait for a bus reset.
WatchdogHandler:
jmp WatchdogHandler
suspendReset:
;Return to suspend mode to wait for a USB bus reset.
mov A, 09h
iowr Status_Control
nop
jmp suspendReset
BusReset:
;Clear all reset bits.
;Set bit 0 (the run bit).
mov A, RunBit
iowr Status_Control
;Set up for enumeration (Endpoint 0 and 1-millisecond interrupts enabled)
mov A, ENUMERATE_MASK
mov [interrupt_mask],A
iowr Global_Interrupt
wait:
;Wait until configured.
iord USB_EP1_TX_Config
cmp A, 0
;Clear the watchdog timer
iowr Watchdog
;If not configured, continue to wait.
jz wait
;When configured, initialize loop_temp.
;Loop_temp adds a delay in the start of transmission of data.
;The chip will respond to the first IN packet no sooner than
;230 milliseconds after enumeration is complete.
;The delay was included in Cypress' joystick code to prevent problems
;that occurred when power cycled off and on or the joystick was plugged
;in before the host powered up.
;I've left it in because it does no harm and
;other hardware might have similar behavior.
;During the delay, the chip sends a NAK in response to any IN packet.
mov A, 0ffh
mov [loop_temp], A
;Enable endpoint 1
iord USB_EP1_TX_Config
or A, 92h
iowr USB_EP1_TX_Config
;======================================================================
; The main program loop.
;======================================================================
main:
;Find out if the loop_temp delay has timed out.
;Loop_temp =0 if not timed out, FFh if timed out.
mov A, [loop_temp]
cmp A, 0Ah
;If no, don't enable transmitting.
jnc no_set
;If yes, enable transmitting.
mov A, 01h
mov [start_send], A
no_set:
;Clear the watchdog timer.
;This has to be done at least once every 8 milliseconds!
iowr Watchdog
iord Port0_Data
nochange:
jmp main
;----------------------------------------------------------------------
;The Endpoint 0 ISR supports the control endpoint.
;This code enumerates and configures the hardware.
;It also responds to Set Report requests that receive data from the host.
;----------------------------------------------------------------------
USB_EP0_ISR:
push A
iord USB_EP0_RX_Status
;Has a Setup packet been received?
and A, 01h
;If no, find out if it's an OUT packet.
jz check_for_out_packet
;If yes, handle it.
;Disable Endpoint 0 interrupts.
mov A,[interrupt_mask]
and A, 0F7h
mov [interrupt_mask], A
iowr Global_Interrupt
;Find out what the Setup packet contains and handle the request.
call StageOne
;Re-enable Endpoint 0 interrupts.
mov A, [interrupt_mask]
or A, 08h
mov [interrupt_mask], A
jmp done_with_packet
check_for_out_packet:
iord USB_EP0_RX_Status
;Is it an OUT packet?
and A, 02h
;If no, ignore it.
jz done_with_packet
;If yes, process the received data.
;Disable Endpoint 0 interrupts.
mov A,[interrupt_mask]
and A, 0F7h
mov [interrupt_mask], A
iowr Global_Interrupt
;For debugging: set Port 0, bit 1 to show that we're here.
; iord Port0_Data
; or a, 2
; iowr Port0_Data
;Read the first byte in the buffer
mov a, [Endpoint_0]
;For debugging: if the first byte =12h, bring Port 0, bit 0 high
; cmp a, 12h
; jnz not_a_match
; iord Port0_Data
; or a, 4
; iowr Port0_Data
not_a_match:
;For debugging, add 1 to each byte read
;and copy the bytes to RAM.
;These bytes will be sent back to the host.
push X
;data_count holds the number of bytes left to read.
;X holds the index of the address to read
;and the index of the address to store the received data.
;Initialize the X register.
mov X, 0
Get_Received_Data:
;Find out if there are any bytes to read.
mov A, 0
cmp A, [data_count]
;Jump if nothing to read.
jz DoneWithReceivedData
;Get a byte.
mov A, [X + Endpoint_0]
;For debugging, increment the received value.
;(Endpoint 1 will send it back to the host.)
;If the value is 255, reset to 0.
;Otherwise increment it.
cmp A, 255
jz ResetToZero
inc A
jmp NewValueSet
ResetToZero:
mov A, 0
NewValueSet:
;Save the value.
mov [X + Data_Byte0], A
;Decrement the number of bytes left to read.
dec [data_count]
;Increment the address to read.
inc X
;Do another
jmp Get_Received_Data
DoneWithReceivedData:
pop X
;For debugging, set Port 0 to match the value written.
; iowr Port0_Data
;Handshake by sending a 0-byte data packet.
call Send0ByteDataPacket
done_with_packet:
;Re-enable Endpoint 0 interrupts.
mov A,[interrupt_mask]
or A, 08h
mov [interrupt_mask], A
ipret Global_Interrupt
;========================================================================
;Control transfers
;========================================================================
;------------------------------------------------------------------------
;Control transfer, stage one.
;Find out whether the request is a standard device or HID-class request,
;the direction of data transfer,
;and whether the request is to a device, interface, or endpoint.
;(from Table 9.2 in the USB spec)
;------------------------------------------------------------------------
StageOne:
;Clear the Setup flag
mov A, 00h
iowr USB_EP0_RX_Status
;Set the StatusOuts bit to cause auto-handshake after receiving a data packet.
mov A, 8
iowr USB_Status_Control
;bmRequestType contains the request.
mov A, [bmRequestType]
;Standard device requests. From the USB spec.
; host to device requests
cmp A, 00h
jz RequestType00 ; bmRequestType = 00000000 device
; cmp A, 01h *** not required ***
; jz RequestType01 ; bmRequestType = 00000001 interface
cmp A, 02h
jz RequestType02 ; bmRequestType = 00000010 endpoint
cmp A, 80h
; device to host requests
jz RequestType80 ; bmRequestType = 10000000 device
cmp A, 81h
jz RequestType81 ; bmRequestType = 10000001 interface
cmp A, 82h
jz RequestType82 ; bmRequestType = 10000010 endpoint
;HID-class device requests. From the HID spec
; host to device requests
cmp A, 21h
jz RequestType21 ; bmRequestType = 00100001 interface
cmp A, 22h ; *** not in HID spec ***
jz RequestType22 ; bmRequestType = 00100010 endpoint
; device to host requests
cmp A, A1h
jz RequestTypeA1 ; bmRequestType = 10100001 interface
; Stall unsupported requests
SendStall:
mov A, A0h
iowr USB_EP0_TX_Config
ret
;----------------------------------------------------------------------
;Control transfer, stage two
;Find out which request it is.
;----------------------------------------------------------------------
;Host to device with device as recipient
RequestType00:
;The Remote Wakeup feature is disabled on reset.
mov A, [bRequest] ; load bRequest
; Clear Feature bRequest = 1
cmp A, clear_feature
jz ClearRemoteWakeup
; Set Feature bRequest = 3
cmp A, set_feature
jz SetRemoteWakeup
; Set the device address to a non-zero value.
; Set Address bRequest = 5
cmp A, set_address
jz SetAddress
; Set Descriptor is optional.
; Set Descriptor bRequest = 7 *** not supported ***
;If wValue is zero, the device is not configured.
;The only other legal value for this firmware is 1.
;Set Configuration bRequest = 9
cmp A, set_configuration
jz SetConfiguration
;Stall unsupported requests.
jmp SendStall
;Host to device with interface as recipient *** not required ***
; RequestType01:
; mov A, [bRequest] ; load bRequest
; There are no interface features defined in the spec.
; Clear Feature bRequest = 1 *** not supported ***
; Set Feature bRequest = 3 *** not supported ***
; Set Interface is optional.
; Set Interface bRequest = 11 *** not supported ***
;Stall unsupported requests.
; jmp SendStall
;Host to device with endpoint as recipient
RequestType02:
mov A, [bRequest] ; load bRequest
; The only standard feature defined for an endpoint is endpoint_stalled.
; Clear Feature bRequest = 1
cmp A, clear_feature
jz ClearEndpointStall
; Set Feature bRequest = 3
cmp A, set_feature
jz SetEndpointStall
;Stall unsupported functions.
jmp SendStall
;Device to host with device as recipient
RequestType80:
mov A, [bRequest] ; load bRequest
; Get Status bRequest = 0
cmp A, get_status
jz GetDeviceStatus
; Get Descriptor bRequest = 6
cmp A, get_descriptor
jz GetDescriptor
; Get Configuration bRequest = 8
cmp A, get_configuration
jz GetConfiguration
;Stall unsupported requests.
jmp SendStall
;Device to host with interface as recipient
RequestType81:
mov A, [bRequest] ; load bRequest
; Get Status bRequest = 0
cmp A, get_status
jz GetInterfaceStatus
; Get Interface returns the selected alternate setting.
; This firmware supports no alternate settings.
; Get Interface bRequest = 10 *** not supported ***
;The HID class defines one more request for bmRequestType=10000001
; Get Descriptor bRequest = 6
cmp A, get_descriptor
jz GetDescriptor
;Stall unsupported functions
jmp SendStall
;Device to host with endpoint as recipient
RequestType82:
mov A, [bRequest] ; load bRequest
; Get Status bRequest = 0
cmp A, get_status
jz GetEndpointStatus
; Get Descriptor bRequest = 6
cmp A, get_descriptor
jz GetDescriptor
; Sync Frame bRequest = 12 *** not supported ***
;Stall unsupported functions.
jmp SendStall
;Check for HID class requests
;Host to device with endpoint as recipient
RequestType21:
mov A, [bRequest] ; load bRequest
; Set Report bRequest = 9
cmp A, set_report
jz SetReport
; Set Idle bRequest = 10
cmp A, set_idle
jz SetIdle
; Set Protocol bRequest = 11
cmp A, set_protocol
jz SetProtocol
;Stall unsupported requests
jmp SendStall
RequestType22:
mov A, [bRequest] ; load bRequest
; Set Report bRequest = 9
cmp A, set_report
jz SetReport
;Stall unsupported requests
jmp SendStall
;Device to host with endpoint as recipient
RequestTypeA1:
mov A, [bRequest] ; load bRequest
; Get Report bRequest = 1
cmp A, get_report
jz GetReport
; Get Idle bRequest = 2
cmp A, get_idle
jz GetIdle
; Get Protocol bRequest = 3
cmp A, get_protocol
jz GetProtocol
;Stall unsupported requests
jmp SendStall
;----------------------------------------------------------------------
;Control transfer, stage three
;Process the request.
;----------------------------------------------------------------------
;The host controls whether or not a device can request a remote wakeup.
; Disable the remote wakeup capability.
ClearRemoteWakeup:
mov A, [wValue]
cmp A, device_remote_wakeup
jnz SendStall
;Handshake by sending a data packet
call Send0ByteDataPacket
mov A, DISABLE_REMOTE_WAKEUP
mov [remote_wakeup_status], A
ret
; Enable the remote wakeup capability.
SetRemoteWakeup:
mov A, [wValue]
cmp A, device_remote_wakeup
;If not a match, stall.
jnz SendStall
;Handshake by sending a 0-byte data packet
call Send0ByteDataPacket
;Perform the request.
mov A, ENABLE_REMOTE_WAKEUP
mov [remote_wakeup_status], A
ret
SetAddress:
; Set the device address to match wValue in the Setup packet.
;Complete the requested action after completing the transaction.
;Handshake by sending a 0-byte data packet.
call Send0ByteDataPacket
;Perform the request
mov A, [wValue]
iowr USB_Device_Address
ret
SetConfiguration:
;Unconfigured: wValue=0, configured: wValue=1.
;Also clear any stall condition and set Data 0/1 to Data0.
;Handshake by sending a 0-byte data packet.
call Send0ByteDataPacket
;Save the configuration status.
mov A, [wValue]
mov [configuration_status], A
;Clear any stall condtion
mov A, 0
mov [endpoint_stall], A
;Set data 0/1 to Data0
iord USB_EP1_TX_Config
and A, ~DataToggle
;Set the configuration status.
iowr USB_EP1_TX_Config
mov A, [configuration_status]
cmp A, 0
;If configured, jump.
jnz device_configured
;If unconfigured:
;Disable Endpoint 1
iord USB_EP1_TX_Config
and A, EFh
iowr USB_EP1_TX_Config
;Disable Endpoint 1 interrupts.
mov A, [interrupt_mask]
and A, EFh
mov [interrupt_mask], A
jmp done_configuration
;If configured:
device_configured:
;Send NAK in response to IN packets
iord USB_EP1_TX_Config
and A,7Fh
;Enable Endpoint 1
or A, 10h
iowr USB_EP1_TX_Config
;Enable interrupts: Endpoint 1 and GPIO
mov A, [interrupt_mask]
or A, 50h
mov [interrupt_mask], A
;Send NAK in response to Endpoint 0 OUT packets.
iord USB_Status_Control
and A,0EFh
iowr USB_Status_Control
done_configuration:
ret
ClearEndpointStall:
;Clear the stall (halt) condition for Endpoint 1.
;wValue = 0.
mov A, [wValue]
cmp A, endpoint_stalled
;If endpoint_stalled = 0, the endpoint isn't stalled
;and there's nothing to clear. Return a Stall for the request.
jnz SendStall
;
;Clear Endpoint 1 stall
;Handshake by sending a 0-byte data packet
call Send0ByteDataPacket
;Clear the stall condition
mov A,0
mov [endpoint_stall], A
;Set Data 0/1 to Data0
iord USB_EP1_TX_Config
and A, ~DataToggle
iowr USB_EP1_TX_Config
;Send NAK in response to Endpoint 0 OUT packets.
iord USB_Status_Control
and A,0EFh
iowr USB_Status_Control
ret
;Stall Endpoint 1
SetEndpointStall:
;wValue = 0.
mov A, [wValue]
cmp A, endpoint_stalled
;If endpoint_stalled = 1, the endpoint is already stalled,
;so return a Stall for this request.
jnz SendStall
;Handshake by sending a 0-byte data packet.
call Send0ByteDataPacket
;Stall the endpoint.
mov A,1
mov [endpoint_stall], A
mov A, 30h
iowr USB_EP1_TX_Config
ret
GetDeviceStatus:
;Device Status is a 2-byte value.
;Bit 0 must be 0 (bus-powered).
;Bit 1 is remote wakeup: 0=disabled, 1=enabled.
;All other bits are unused.
;Return to status bytes to the host.
mov A, 2
mov [data_count], A
;control_read_table holds the two possible values for device status.
;Get the address of the first value.
mov A, (get_dev_status_table - control_read_table)
;Add an index value to select the correct value.
add A, [remote_wakeup_status]
;Send the value.
jmp SendDescriptor
GetDescriptor:
;The high byte of wValue contains the descriptor type.
;The low byte of wValue contains the descriptor index.
mov A, [wValueHi] ; load descriptor type
;Test for standard descriptor types first.
;Supported descriptor types are device, configuration, string.
;Unsupported descriptor types are interface, endpoint.
; Get Descriptor (device) wValueHi = 1
cmp A, device
jz GetDeviceDescriptor
; Get Descriptor (configuration) wValueHi = 2
cmp A, configuration
jz GetConfigurationDescriptor
; Get Descriptor (string) wValueHi = 3
cmp A, string
jz GetStringDescriptor
; Test for HID-class descriptor types.
; Get Descriptor (HID) wValueHi = 21h
cmp A, HID
jz GetHIDDescriptor
; Get Descriptor (report) wValueHi = 22h
cmp A, report
jz GetReportDescriptor
; Get Descriptor (physical) wValueHi = 23h *** not supported ***
;Stall unsupported requests.
jmp SendStall
GetConfiguration:
;Send the current device configuration.
;0 = unconfigured, 1 = configured.
;Send 1 byte
mov A, 1
mov [data_count], A
;Get the address of the data to send.
mov A, (get_configuration_status_table - control_read_table)
;Add an index to point to the correct configuration.
add A, [configuration_status]
;Send the data.
jmp SendDescriptor
GetInterfaceStatus:
;Interface status is 2 bytes, which are always 0.
;Send 2 bytes.
mov A, 2
mov [data_count], A
;Get the address of the data to send.
mov A, (get_interface_status_table - control_read_table)
;Send the data.
jmp SendDescriptor
GetEndpointStatus:
;Endpoint status is 2 bytes.
;Bit 0 = 0 when the endpoint is not stalled.
;Bit 0 = 1 when the endpoint is stalled.
;All other bits are unused.
;Send 2 bytes.
mov A, 2
mov [data_count], A
;Get the stall status.
mov A, [endpoint_stall]
;Shift left to get an index (0 or 2) to point to data
;in the endpoint status table
asl A
;Get the address of the data to send.
add A, (get_endpoint_status_table - control_read_table)
;Send the data.
jmp SendDescriptor
SetReport:
;The CY7C63000 doesn't support interrupt-mode OUT transfers.
;So the host uses Control transfers with Set_Report requests
;to get data from the device.
;Get the report data.
;For debugging: set Port 0, bit 0 =1 to show that we're here.
; iord Port0_Data
; or a, 1
; iowr Port0_Data
;Find out how many bytes to read. This value is in WLength.
;Save the length in data_count.
mov A, [wLength]
mov [data_count], A
;Enable receiving data at Endpoint 0 by setting the EnableOuts bit
;The bit clears following any Setup or OUT transaction.
iord USB_Status_Control
or A, 10h
;Clear the StatusOuts bit to disable automatic sending of ACK after
;receiving a valid status packet in a Control read (IN) transfer.
;Otherwise, the USB engine will respond to a data OUT packet with a Stall.
and A, F7h
iowr USB_Status_Control
;Now we're ready to receive the report data.
;An Endpoint 0 OUT interrupt indicates the arrival of the report data.
ret
SetIdle:
jmp SendStall ; *** not supported ***
SetProtocol:
;Switches between a boot protocol (wValue=0) and report protocol (wValue=1).
;This firmware doesn't distinguish between protocols.
mov A, [wValue]
mov [protocol_status], A
call Send0ByteDataPacket
ret
GetReport:
;Sends a report to the host.
;The high byte of wValue contains the report type.
;The low byte of wValue contains the report ID.
;Not supported (Use interrupt transfers to send data.)
jmp SendStall
GetReportDescriptor:
;Save the descriptor length
mov A, (end_hid_report_desc_table - hid_report_desc_table)
mov [data_count], A
;Get the descriptor's starting address.
mov A, (hid_report_desc_table - control_read_table)
call SendDescriptor
ret
GetIdle:
;Not supported
jmp SendStall
GetProtocol:
;Send the current protocol status.
;Send 1 byte.
mov A, 1
mov [data_count], A
;Get the address of the data to send.
mov A, (get_protocol_status_table - control_read_table)
;Add an index that points to the correct data.
add A, [protocol_status]
;Send the data.
jmp SendDescriptor
; Standard Get Descriptor routines
;
;Send the device descriptor.
GetDeviceDescriptor:
;Get the length of the descriptor
;(stored in the first byte in the device descriptor table).
mov A, 0
index device_desc_table
mov [data_count], A
;Get the starting address of the descriptor.
mov A, (device_desc_table - control_read_table)
;Send the descriptor.
jmp SendDescriptor
GetConfigurationDescriptor:
;Send the configuration descriptor.
;Get the length of the descriptor.
mov A, (end_config_desc_table - config_desc_table)
mov [data_count], A
;Get the starting address of the descriptor.
mov A, (config_desc_table - control_read_table)
;Send the descriptor.
jmp SendDescriptor
GetStringDescriptor:
;Use the string index to find out which string it is.
mov A, [wValue]
cmp A, 0h
jz LanguageString
cmp A, 01h
jz ManufacturerString
cmp A, 02h
jz ProductString
; cmp A, 03h
; jz SerialNumString
; cmp A, 04h
; jz ConfigurationString
; cmp A, 05h
; jz InterfaceString
; No other strings supported
jmp SendStall
SendDescriptor:
;The starting address of the descriptor is in the accumulator. Save it.
mov [data_start], A
;Get the descriptor length.
call get_descriptor_length
;Send the descriptor.
call control_read
ret
;Send the requested string.
;For each, store the descriptor length in data_count, then send the descriptor.
LanguageString:
mov A, (USBStringDescription1 - USBStringLanguageDescription)
mov [data_count], A
mov A, (USBStringLanguageDescription - control_read_table)
jmp SendDescriptor
ManufacturerString:
mov A, ( USBStringDescription2 - USBStringDescription1)
mov [data_count], A
mov A, (USBStringDescription1 - control_read_table)
jmp SendDescriptor
ProductString:
mov A, ( USBStringDescription3 - USBStringDescription2)
mov [data_count], A
mov A, (USBStringDescription2 - control_read_table)
jmp SendDescriptor
;SerialNumString:
; mov A, ( USBStringDescription4 - USBStringDescription3)
; mov [data_count], A
; mov A, (USBStringDescription3 - control_read_table)
; jmp SendDescriptor
;ConfigurationString:
; mov A, ( USBStringDescription5 - USBStringDescription4)
; mov [data_count], A
; mov A, (USBStringDescription4 - control_read_table)
; jmp SendDescriptor
;InterfaceString:
; mov A, ( USBStringEnd - USBStringDescription5)
; mov [data_count], A
; mov A, (USBStringDescription5 - control_read_table)
; jmp SendDescriptor
; HID class Get Descriptor routines
;
GetHIDDescriptor:
;Send the HID descriptor.
;Get the length of the descriptor.
mov A, (Endpoint_Descriptor - Class_Descriptor)
mov [data_count], A
;Get the descriptor's starting address.
mov A, ( Class_Descriptor - control_read_table)
;Send the descriptor.
call SendDescriptor
ret
;======================================================================
;USB support routines
;======================================================================
get_descriptor_length:
;The host sometimes lies about the number of bytes it
;wants from a descriptor.
;A request to get a descriptor should return the smaller of the number
;of bytes requested or the actual length of the descriptor.
;Get the requested number of bytes to send
mov A, [wLengthHi]
;If the requested high byte is >0,
;ignore the high byte and use the firmware's value.
;(255 bytes is the maximum allowed.)
cmp A, 0
jnz use_actual_length
;If the low byte =0, use the firmware's value.
mov A, [wLength]
cmp A, 0
jz use_actual_length
;If the requested number of bytes => the firmware's value,
;use the firmware's value.
cmp A, [data_count]
jnc use_actual_length
;If the requested number of bytes < the firmware's value,
;use the requested number of bytes.
mov [data_count], A
use_actual_length:
ret
Send0ByteDataPacket:
;Send a data packet with 0 bytes.
;Use this handshake after receiving an OUT data packet.
;Enable responding to IN packets and set Data 0/1 to Data 1.
mov A, C0h
iowr USB_EP0_TX_Config
;Enable interrupts.
mov A, [interrupt_mask]
iowr Global_Interrupt
WaitForDataToTransfer:
;Wait for the data to transfer.
;Clear the watchdog timer
iowr Watchdog
;Bit 7 of USB_EP0_TX_Config is cleared when the host acknowledges
;receiving the data.
iord USB_EP0_TX_Config
and A, 80h
jnz WaitForDataToTransfer
ret
control_read:
;Do a Control Read transfer.
;The device receives a Setup packet in the Setup stage,
;sends 1 or more data packets (IN) in the Data stage,
;and receives a 0-length data packet (OUT) in the Status stage.
;Before calling this routine, the firmware must set 2 values:
;data_start is the starting address of the descriptor to send,
;expressed as an offset from the control read table.
;data_count is the number of bytes in the descriptor.
push X
;Set the Data 0/1 bit to 0.
mov A, 00h
mov [endp0_data_toggle], A
control_read_data_stage:
;Initialize count variables.
mov X, 00h
mov A, 00h
mov [loop_counter], A
;Clear the Setup bit.
iowr USB_EP0_RX_Status
;Check the Setup bit.
iord USB_EP0_RX_Status
and A, 01h
;If not cleared, another setup packet has arrived,
;so exit the routine.
jnz control_read_status_stage
;Set the StatusOuts bit to 1 to cause the device to automatically return
;ACK in response to a received OUT packet in the Status stage.
mov A, 08h
iowr USB_Status_Control
;If there is no data to send, prepare a 0-length data packet.
;(The host might require a final 0-length packet if the descriptor is
;a multiple of 8 bytes.)
mov A, [data_count]
cmp A, 00h
jz dma_load_done
dma_load_loop:
;Copy up to 8 bytes for transmitting into Endpoint 0's buffer
;and increment/decrement the various counting variables.
;Place the byte to send in the accumulator:
;(control_read_table) + (data_start).
mov A, [data_start]
index control_read_table
;Place the byte in Endpoint 0's buffer.
mov [X + Endpoint_0], A
;Increment the offset of the data being sent.
inc [data_start]
;Increment the offset of Endpoint 0's buffer.
inc X
;Increment the number of bytes stored in the buffer.
inc [loop_counter]
;Decrement the number of bytes left to send.
dec [data_count]
;If the count = 0, there's no more data to load.
jz dma_load_done
;If 8 bytes haven't been loaded into the buffer, get another byte.
;If 8 bytes have been loaded, it's the maximum for the transaction,
;so send the data.
mov A, [loop_counter]
cmp A, 08h
jnz dma_load_loop
dma_load_done:
;Send the data.
;Check the Setup bit.
;If it's not 0, another Setup packet has arrived,
;so exit the routine.
iord USB_EP0_RX_Status
and A, 01h
jnz control_read_status_stage
;Set the bits in the USB_EP0_TX_Config register.
;Toggle the Data 0/1 bit.
mov A, [endp0_data_toggle]
xor A, 40h
mov [endp0_data_toggle], A
;Enable responding to IN token packets.
or A, 80h
;The low 4 bits hold the number of bytes to send.
or A, [loop_counter]
iowr USB_EP0_TX_Config
;Enable interrupts
mov A, [interrupt_mask]
iowr Global_Interrupt
wait_control_read:
;Clear the watchdog timer
iowr Watchdog
;Wait for the data to transfer and the host to acknowledge,
;indicated by Bit 7 = 0.
iord USB_EP0_TX_Config
and A, 80h
;When all of the transaction's data has transferred,
;find out if there is more data to send in the transfer.
jz control_read_data_stage
;Find out if the host has sent an OUT packet to acknowledge
;and end the transfer.
iord USB_EP0_RX_Status
and A, 02h
jz wait_control_read
control_read_status_stage:
;The transfer is complete.
pop X
mov A, [interrupt_mask]
iowr Global_Interrupt
ret
;======================================================================
;Lookup Tables
;Contain the descriptors and the codes for status indicators.
;The firmware accesses the information by referencing a specific
;table's address as an offset from the control_read_table.
;======================================================================
control_read_table:
device_desc_table:
db 12h ; Descriptor length (18 bytes)
db 01h ; Descriptor type (Device)
db 10h,01h ; Complies with USB Spec. Release (0110h = release 1.10)
db 00h ; Class code (0)
db 00h ; Subclass code (0)
db 00h ; Protocol (No specific protocol)
db 08h ; Maximum packet size for Endpoint 0 (8 bytes)
db 25h,09h ; Vendor ID (Lakeview Research, 0925h)
db 34h,12h ; Product ID (1234)
db 01h,00h ; Device release number (0001)
db 01h ; Manufacturer string descriptor index
db 02h ; Product string descriptor index
db 00h ; Serial Number string descriptor index (None)
db 01h ; Number of possible configurations (1)
end_device_desc_table:
config_desc_table:
db 09h ; Descriptor length (9 bytes)
db 02h ; Descriptor type (Configuration)
db 22h,00h ; Total data length (34 bytes)
db 01h ; Interface supported (1)
db 01h ; Configuration value (1)
db 00h ; Index of string descriptor (None)
db 80h ; Configuration (Bus powered)
db 32h ; Maximum power consumption (100mA)
Interface_Descriptor:
db 09h ; Descriptor length (9 bytes)
db 04h ; Descriptor type (Interface)
db 00h ; Number of interface (0)
db 00h ; Alternate setting (0)
db 01h ; Number of interface endpoint (1)
db 03h ; Class code ()
db 00h ; Subclass code ()
db 00h ; Protocol code ()
db 00h ; Index of string()
Class_Descriptor:
db 09h ; Descriptor length (9 bytes)
db 21h ; Descriptor type (HID)
db 00h,01h ; HID class release number (1.00)
db 00h ; Localized country code (None)
db 01h ; # of HID class dscrptr to follow (1)
db 22h ; Report descriptor type (HID)
; Total length of report descriptor
db (end_hid_report_desc_table - hid_report_desc_table),00h
Endpoint_Descriptor:
db 07h ; Descriptor length (7 bytes)
db 05h ; Descriptor type (Endpoint)
db 81h ; Encoded address (Respond to IN, 1 endpoint)
db 03h ; Endpoint attribute (Interrupt transfer)
db 06h,00h ; Maximum packet size (6 bytes)
db 0Ah ; Polling interval (10 ms)
end_config_desc_table:
;----------------------------------------------------------------------
;The HID-report descriptor table
;----------------------------------------------------------------------
hid_report_desc_table:
db 06h, A0h, FFh ; Usage Page (vendor defined) FFA0
db 09h, 01h ; Usage (vendor defined)
db A1h, 01h ; Collection (Application)
db 09h, 02h ; Usage (vendor defined)
db A1h, 00h ; Collection (Physical)
db 06h, A1h, FFh ; Usage Page (vendor defined)
;The input report
db 09h, 03h ; usage - vendor defined
db 09h, 04h ; usage - vendor defined
db 15h, 80h ; Logical Minimum (-128)
db 25h, 7Fh ; Logical Maximum (127)
db 35h, 00h ; Physical Minimum (0)
db 45h, FFh; Physical Maximum (255)
; db 66h, 00h, 00h; Unit (None (2 bytes))
db 75h, 08h ; Report Size (8) (bits)
db 95h, 02h ; Report Count (2) (fields)
db 81h, 02h ; Input (Data, Variable, Absolute)
;The output report
db 09h, 05h ; usage - vendor defined
db 09h, 06h ; usage - vendor defined
db 15h, 80h ; Logical Minimum (-128)
db 25h, 7Fh ; Logical Maximum (127)
db 35h, 00h ; Physical Minimum (0)
db 45h, FFh ; Physical Maximum (255)
; db 66h, 00h, 00h; Unit (None (2 bytes))
db 75h, 08h ; Report Size (8) (bits)
db 95h, 02h ; Report Count (2) (fields)
db 91h, 02h ; Output (Data, Variable, Absolute)
db C0h ; End Collection
db C0h ; End Collection
end_hid_report_desc_table:
;----------------------------------------------------------------------
;String Descriptors
;----------------------------------------------------------------------
;Define the strings
; string 0
USBStringLanguageDescription:
db 04h ; Length
db 03h ; Type (3=string)
db 09h ; Language: English
db 04h ; Sub-language: US
; string 1
;The Length value for each string =
;((number of characters) * 2) + 2
USBStringDescription1: ; IManufacturerName
db 1Ah ; Length
db 03h ; Type (3=string)
dsu "USB Complete" ;
; string 2
USBStringDescription2: ; IProduct
db 16h ; Length
db 03h ; Type (3=string)
dsu "HID Sample" ;
;string 3
;If the firmware contains a serial number, it must be unique
;for each device or the devices may not enumerate properly.
USBStringDescription3: ; serial number
; string 4
;USBStringDescription4: ; configuration string descriptor
; db 16h ; Length
; db 03h ; Type (3=string)
; dsu "Sample HID" ;
;string 5
;USBStringDescription5: ; configuration string descriptor
; db 32h ; Length
; db 03h ; Type (3=string)
; dsu "EndPoint1 Interrupt Pipe" ;
USBStringEnd:
;----------------------------------------------------------------------
;Status information.
;The status can apply to the device or an interface or endpoint.
;An index selects the correct value.
;----------------------------------------------------------------------
get_dev_status_table:
db 00h, 00h ; remote wakeup disabled, bus powered
db 02h, 00h ; remote wakeup enabled, bus powered
get_interface_status_table:
db 00h, 00h ; always return both bytes zero
get_endpoint_status_table:
db 00h, 00h ; not stalled
db 01h, 00h ; stalled
get_configuration_status_table:
db 00h ; not configured
db 01h ; configured
get_protocol_status_table:
db 00h ; boot protocol
db 01h ; report protocol