USB CDC Communications for Dummies!

[Andre_Pretorius]

Can sombody please give me a hint what i am do-ing wrong i keep getting the following error
C:\PBP246\PIC18EXT.BAS ERROR Line 12: Redefinition of VAR.
Here is the code i use

INCLUDE "MODEDEFS.BAS"
INCLUDE "18F4550.BAS"		; USB descriptors for CDC demo

DEFINE OSC 20				' Define crystal as 20Mhz

'Define ACDIN parameters
Define ADC_BITS 10 			' Set number of bits in result
DEFINE ADC_CLOCK 3 			' Set clock source ( 3 = RC )
DEFINE ADC_SAMPLEUS 50 		' Set sampling time to micro-seconds

'This Part set PORTA 0-3 an analog inputs,4 as digital 
TRISA = %00011111 			'set PORTA 0-5 as inputs
ADCON1 = %00001010 			'ADC use vss and vdd as ref.
ADCON2 = %10000111			'FRC (clock derived from A/D RC oscillator),Right justify output


TRISD = %00001111			'Set port d 0-3 as inputs and 4-7 as outputs
TRISB = %10011000

'**************************************Variables*********************************************
buffer	Var	Byte[16]
cnt	Var	Byte
LED	Var	PORTD.4

USBInit
Low LED		' LED off

'**************************************Main Program******************************************
' Wait for USB input
idleloop:
	USBService	' Must service USB regularly
	cnt = 1	' Specify input buffer size
	USBIn 3, buffer, cnt, idleloop

' Message received
	Toggle LED

outloop:
	USBService	' Must service USB regularly
	USBOut 3, buffer, cnt, outloop

	Goto idleloop	' Wait for next buffer


END

[arniepj]

Comment out INCLUDE "18F4550.BAS and add the following files to the project folder.It compiled fine for me and connected to the pc usb,but your code only flashes an led.
CDCDESC.ASM
usb18.asm
18F4550.BAS
USBDESC.ASM
usb18.inc
usb18mem.asm

[Andre_Pretorius]

Thank you got it running, the problem seemed to be that my pic basic pro was installed in PBP246 and not PBP as one of the references needed it to be, Just fixing the path seemed to repaired everything

[kirtcathey]

Have a very basic question that I want to confirm before going forward...

In the PBP manual, USBIN is described as:

++++++++++++++++++++++++++++++++++
USBIN Endpoint, Buffer, Countvar, Label

Get any available USB data for the Endpoint and places it in the Buffer. Buffer must be a byte array of suitable length to contain the data. Countvar will contain the number of bytes transferred to the buffer. Label will be jumped to if no data is available.
++++++++++++++++++++++++++++++++++

It was my understanding that with or without data, that this function always went to Label. Then within Label we perform a test to see if Buffer has new data and route execution from there.

However, the way that the PBP manual describes it is that if no data is input, then program execution jumps to Label.

Which one is it? Does this function always go to Label after reading 8 bytes (or however many specified during HID config. and specified in CountVar) even if there was or was not any input? Or, does this function only jump to Label when no bytes are read from the bus?

[sputnik77]

Do any of you have a working hex for a 2550 on a 20MHz crystal that I can try?

I have tried everything I have found and still cannot get anything to work. I always get "Unknown Device" error no matter what.


The vendors of the compilers really need to give more concise information on USB communications.

[kirtcathey]

I was consistently getting USB device recognition when I connected, but ended with an unknown device when I did not have the configuration directives set appropriately. Read the above thread between Darrel and myself. Or, you can put in a 4MHz chip and just use the code I posted a couple days ago...

[sputnik77]

OK, I was finally able to get this working.

I was using the USBTEST files above.

I added the extra configs for the write protect stuff that was not in the code and VOILA!!!, it works now.

It seems to be an issue with the PicKit2. It barks at you if those configs are not included, it usually isnt an issue as long as the important ones are defined. However in this case I assume since they were missing , the PicKit2 changed some of the needed configs to something incompatible for some reason.

This should not be the issue, however it works. I removed the extra configs and it doesnt work, add them and its just fine!!!

Now to figure out how to get data INTO the pic.

[sputnik77]

Have a very basic question that I want to confirm before going forward...

In the PBP manual, USBIN is described as:

++++++++++++++++++++++++++++++++++
USBIN Endpoint, Buffer, Countvar, Label

Get any available USB data for the Endpoint and places it in the Buffer. Buffer must be a byte array of suitable length to contain the data. Countvar will contain the number of bytes transferred to the buffer. Label will be jumped to if no data is available.
++++++++++++++++++++++++++++++++++

It was my understanding that with or without data, that this function always went to Label. Then within Label we perform a test to see if Buffer has new data and route execution from there.

However, the way that the PBP manual describes it is that if no data is input, then program execution jumps to Label.

Which one is it? Does this function always go to Label after reading 8 bytes (or however many specified during HID config. and specified in CountVar) even if there was or was not any input? Or, does this function only jump to Label when no bytes are read from the bus?

I have some of the same questions. What IS and endpoint anyway???


In my findings the above example from the manual is backwards. It will only jump to the label if the buffer is FULL. It seems to sit and wait until the specified number of bytes have been received.

[test153]

Note if using the USB bus power to power your pic remember that the max current your pic circuit can draw is 100ma! Anymore and you may blow your usb port! If in doubt stick in a fuse, or use external power.

As far as I know a USB 2.0 device can draw upto 500mA once communication is established and the host grants the request for drawing more power, otherwise the device is only able to get 100mA from the host. I doubt that you will blow the USB port if you draw more then 100mA.

[ricgar]

Hi Guys

I'm pretty new to all of this, but here's my attempt.

I've attached a schematic of the device i am using.

What i am attempting to make here is some sort of USB to Serial Port Converter.

The code i loaded onto the chip is as follows:

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2009 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 2009/01/02                                        *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
@   __CONFIG	_CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@	__CONFIG	_CONFIG1H, _FOSC_HSPLL_HS_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
'_CONFIG1H, _FOSC_XTPLL_XT_1H 
@	__CONFIG	_CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L  & _BORV_28_2L  & _VREGEN_ON_2L
@	__CONFIG	_CONFIG2H, _WDT_OFF_2H
@	__CONFIG	_CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H & _CCP2MX_ON_3H
@	__CONFIG	_CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L

' ****************************** Configure Hardware *********************************************
trisb = %11111100
trisc = %10111111       	' Set TX (PortC.6) to out, rest in
spbrg = 25            		' Calculate ((CPU speed mhz/Baud)/16)- 1  25 = 115200 baud  EX:((48000000/115200)/16)-1
rcsta = %10010000       	' Enable serial port and continuous receive
txsta = %00100000       	' Enable transmit and asynchronous mode/brgh = 0 bit 2
baudcon =%00001000			' Bit3 = 1: High speed usart 16 bit  

'***************************** Variables ******************************************
USBBufferTX Var Byte[1]
USBBufferRX var Byte[1]
USBBufferCount Var Byte
SerBufferTX Var Byte
SerBufferRX var Byte[1]
BufferRX var Byte
SerBufferCount Var Byte
Indexer var byte
Xmit_Start var bit									' Start serial data transmission
Status_Bits var byte								' Status bits to Pc
Data_Delay var word									' Delay for dataout
Data_Out var word									' Data 

Status_Bits = 0

LED	Var	PORTB.1

Define  OSC     48

	USBInit
	high led
	pause 1000
	Low LED		' LED off
    USBService

    for Indexer = 0 to 0
	   USBBufferRX[Indexer]= 0
    next

    usbbuffercount = 1
    
    
main:
    goSUB usb_rx
    goSUB com_rx
goto main    

	' Transmit USB Data     
USB_TX:
					' TX buffer size
USBService 
USBOut 3, serBufferrX, USBBufferCount, main 			' Transmit data		
RETURN

	' Receive USB Data 
USB_RX: 
USBService 											
USBIn 3, USBBufferRX, USBBufferCount, exitsub 		' Receive data if available,then exit
serbuffertx=usbbufferrx[0]
goSUB com_tx
return
'GOSUB Main


'Serial Receive

COM_RX:
hserin 1, exitsub, [bufferrx]
serbufferrx[0]=bufferrx
goSUB usb_TX
goSUB main

'Serial Transmit
COM_TX:
hserout [serbuffertx]
RETURN

exitsub:
return

Now this code compiles and i can connect via a hyperterminal to both the USB virtual and the physical Serial port. However if i enter anything in either of hyperterminals, it gives nothing and after a while of constant typing the hyperterminals start freezing on me. So i take it i've done something horrifically wrong.

Any suggestions?