Help me with ADC function problem of 16F877A

ADC Problem with 16F877A

Hi,
I'm in trouble with adc function of 16F877A.I am using port A0,A1,A5,E0,E1,E2.When i measure voltage between ports and GND they are usually at 1 milivolt or 2 milivolts.But when i log them adc function returns 100-120 values equals to 2.0V - 2.5V.When i measure E2 it gives 50 milivolt when i dont apply voltage on it(when idle i mean)!! My device does not work properly now please help!!

My code has written with ccs c compiler v3.155

My code :

#include <16F877A.h>
#device adc=8
#use delay(clock=4000000)
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7)


void main() {

int v1,v2,v3,v4,v5,v6;
char ON;

setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
set_tris_d(0x00);

ON = 1;
printf("3A75D5FA\r\n");

while (1)
{

delay_ms(500);

set_adc_channel( 0 );delay_us(100);v1 = read_adc();delay_us(100);
set_adc_channel( 1 );delay_us(100);v2 = read_adc();delay_us(100);
set_adc_channel( 4 );delay_us(100);v3 = read_adc();delay_us(100);
set_adc_channel( 5 );delay_us(100);v4 = read_adc();delay_us(100);
set_adc_channel( 6 );delay_us(100);v5 = read_adc();delay_us(100);
set_adc_channel( 7 );delay_us(100);v6 = read_adc();delay_us(100);

printf("Value:%2X/%2X/%2X/%2X/%2X/%2X!",v1,v2,v3,v4,v5,v6);

if (ON == 1) {output_high(PIN_D2);ON = 0;} else {output_low(PIN_D2);ON = 1;}

v1=0;v2=0;v3=0;v4=0;v5=0;v6=0;
}

}


I uploaded schematic if you want to look at.

Analyzer.

Did you look at the erratas ?

**broken link removed**
**broken link removed**

I had big problems using 16F877a above 4MHz clock and returned and exchanged them to non A types.

We wanted o save some money using the A types as they are a little cheaper ...

Especially look at the manufacturing date:
big problems before 0242 !!

best luck

Hi,
Thank you for your reply.I am using newer mcu's.I solved the problem now.It was a hardware problem.

Analyzer.