USB CDC Communications for Dummies!

[kirtcathey]

Are you getting it to recognize the device when you initially plug into your computer?

This is the most straightforward and easiest to run so far. It is based on SquibbCake's code in the first posting.

Arnie >> What was your code supposed to do? When I thought I got it working (which it does for the most part), it was blowing a bunch of "B" and special characters across the screen. But upon closer review of your code, it looks like it is looking for user input, then sending data out on USART TX pins. Can you tell us how it is supposed to function and include a link to a similar schematic?

[kirtcathey]

I have gone throught the microchip document fairly thoroughly but have a few questions about some of the PicBasic Pro commands. In the USBIN and USBOUT functions, the first argument is endpoint. What is this referring to? How is that number determined?

[arniepj]

The code is a test program and actually works with a VB6 interface and yes it is looking for commands.The usart output was initially just to let me know the code was running.You can have serial data simultaneously on the pc's comport and the virtual comport(usb).From a terminal program send MX8 to start the usb xmit and MX9 to stop.If you want the VB code http://www.picbasic.co.uk/forum/show....php?t=7372.If you think the CDC demo was fun,Hid is even better.

[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?