PIC16C765T-I/L【PDF 139/165 页】IC MCU OTP 8KX14 USB 44PLCC

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2000 Microchip Technology Inc.

Preliminary

DS41124C-page 75

PIC16C745/765

10.9.7

EXAMPLE

This example shows how the USB functions are used.

This example first initializes the USB peripheral, which

allows the host to enumerate the device. The enumer-

ation process occurs in the background, via an Inter-

rupt

Service

Routine.

This

function

waits

until

enumeration is complete, and then polls EP1 OUT to

see if there is any data available. When a buffer is

available, it is copied to the IN buffer.

Presumably

your application would do something more interesting

with the data than this example.

; ******************************************************************

; Demo program that initializes the USB peripheral, allows the Host

;

to Enumerate, then copies buffers from EP1OUT to EP1IN.

; ******************************************************************

main

call

InitUSB

; Set up everything so we can enumerate

ConfiguredUSB

; wait here until we have enumerated.

CheckEP1

; Check Endpoint 1 for an OUT transaction

bankisel

buffer

; point to lower banks

movlw

buffer

movwf

FSR

; point FSR to our buffer

movlw

; check end point 1

call

GetUSB

; If data is ready, it will be copied.

btfss

STATUS,C

; was there any data for us?

goto

PutBuffer

; Nope, check again.

; Code host to process out buffer from host

PutBuffer

bankisel

buffer

; point to lower banks

; save buffer length

movlw

buffer

movwf

FSR

; point FSR to our buffer

movlw

0x81

; put 8 bytes to Endpoint 1

call

PutUSB

btfss

STATUS,C

; was it successful?

goto

PutBuffer

; No: try again until successful

goto

idleloop

; Yes: restart loop

end

10.9.8

ASSEMBLING THE CODE

The code is designed to be used with the linker. There

is no provision for includable files. The code comes

packaged as several different files:

USB_CH9.ASM - handles all the Chapter 9 com-

mand processing.

USB_DEFS.INC - #Defines used throughout the

code.

USB_MAIN.ASM - Sample interrupt service

routine.

HIDCLASS.ASM - Handles the HID class specific

commands.

10.9.8.1

Assembly Options

There are two #defines at the top of the code that con-

trol assembly options.

10.9.8.2

#define ERRORCOUNTERS

This define includes code to count the number of

errors that occur, by type of error. This requires extra

code and RAM locations to implement the counters.

10.9.8.3

#define FUNCTIONIDS

This is useful for debug. It encodes the upper 6 bits of

USWSTAT (0x197) to indicate which function is exe-

cuting. See the defines in USB_DEFS.INC for the

codes that will be encoded.

745cov.book Page 75 Wednesday, August 2, 2000 8:24 AM

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