Madara wrote:I am trying to make usb based oscilloscope.USB startups and data transfers work well.However on starting adc channel it throws an usb error "-5".

and the code works sometimes too..
The code is:

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <avr/wdt.h>
#include <avr/pgmspace.h>
#include "usbdrv.h"
#include "oddebug.h"


#define START_ADC 0
#define STOP_ADC 1
#define READ_VAL 2

static int8_t j=0,k;
static uchar replyBuf[128];

USB_PUBLIC uchar usbFunctionSetup(uchar data[8]) {
usbRequest_t *rq = (void *)data; // cast data to correct type

switch(rq->bRequest) {

case START_ADC:
ADCSRA|=((1<<ADEN)|(1<<6));
return 0;
case STOP_ADC:
ADCSRA&=(0<<ADEN);
return 0;
case READ_VAL:
usbMsgPtr=replyBuf;
k=j;
j=0;
return k;
}

return 0;
}

int __attribute__((noreturn)) main(void) {
uchar i;

wdt_enable(WDTO_1S); // enable 1s watchdog timer

odDebugInit();
DBG1(0x00, 0, 0);

usbInit();
usbDeviceDisconnect(); // enforce re-enumeration

i=0;
while(--i){ /* fake USB disconnect for > 250 ms */
wdt_reset();
_delay_ms(1);
}

usbDeviceConnect();
sei(); // Enable interrupts after re-enumeration

DBG1(0x01, 0, 0);
ADCSRA=0x2f;
ADMUX=0x40;

while(1) {
DBG1(0x02, 0, 0);
wdt_reset();
usbPoll();
}
}

ISR(ADC_vect,ISR_NOBLOCK)
{
replyBuf[j]=ADCL;
replyBuf[++j]=ADCH;
j++;
}


Please help...... I am using 16Mhz crystall.