Little ADC Help PLease !!!

[sean-h]

Here is a bit of code I am using at the moment that seems to work well.

Wait for 255 to be sent from PC then samples and sends reply back.

'************************************

'Define ADCIN parameters
' Set number of bits in result
DEFINE ADC_BITS 10 

' Set clock source (3=rc)
DEFINE ADC_CLOCK 3 

' Set sampling time in microseconds
DEFINE ADC_SAMPLEUS 10 

' Set PORTA to all input
TRISA = %11111111 

' Set up ADCON1 to tell it to right justify and enable A/D channel 0
ADCON1 = %10000010 

' Maximum buffer size
USBBufferSizeMax con 8

' Input buffer size
USBBufferSizeTX con 8 

' Output buffer size
USBBufferSizeRX con 8

' The USB buffer variables...
USBBuffer Var ByteUSBBufferSizeMax 
USBBufferCount Var Byte 

' Other variables
datawait var byte

' Create variable to store result
adcVar VAR WORD 


'Wait Half a second let ADC settle
pause 500



' Initialise USB...
usbinit 

***' ***************************************************************
***' * Start of Main Routine ** **
***' ***************************************************************
usbstart:

'Clear main wait variable
datawait=0

'Go check for a USB packet
gosub DoUSBIn

' Check data Received in and load variables
datawait=usbbuffer(0)

'Check if PC wants ADC sent back 
if datawait=255 then

'Gosub main ADC routine
gosub main

endif

'Go back to the start and wait for the next command 
goto usbstart


*' *************************************************************
*' * Main Sample Routine **
*' *************************************************************
main: 


' Read channel 0 
ADCIN 0, adcVar 

' Wait.01 second
Pause 10 

'Shift the result down to 10 bits 
ADcvar = adcvar >> 6


'Set the Result
usbbuffer(0)=adcvar.highbyte
usbbuffer(1)=adcvar.Lowbyte 


'Send it out to PC
gosub dousbout


return

*' *************************************************************
*' * Receive data from the USB bus **
*' *************************************************************
DoUSBIn:

' RX buffer size
USBBufferCount = USBBufferSizeRX 

' Keep connection alive
USBService 

' Read data, if available 
USBIn 1, USBBuffer, USBBufferCount, DoUSBIn 

return

*' *************************************************************
*' * Send Data out **
*' *************************************************************
DoUSBOut:

' TX buffer size 
USBBufferCount = USBBufferSizeTX 

' Keep connection alive 
USBService 

' If bus available, transmit data 
USBOut 1, USBBuffer, USBBufferCount, DoUSBOut 

return

Cheers

Sean.