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spilz
Joined: 30 Jan 2012
Posts: 219
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| ADC and 18F2550 |
 Posted: Tue Oct 30, 2012 2:30 am |
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Hi everybody !
I'm trying to use ADC on my 18F2550 with PCWHD 4.065.
the goal is to read ADC on pin A0, other pins A1 to A5 are used as logic output.
my code :
| Code: | #include <18F2550.h>
#device adc=10
#fuses INTRC_IO,NOWDT,NOMCLR,NOPROTECT,NOLVP,NODEBUG,PLL1,CPUDIV1,NOBROWNOUT
#use delay(clock=8000000,restart_wdt)
#define PICKIT_UART
#define rs232_pickit2_rx PIN_B6
#define rs232_pickit2_tx PIN_B7
#use rs232(baud=9600,parity=N,xmit=rs232_pickit2_tx,rcv=rs232_pickit2_rx,bits=8,TIMEOUT=500,STREAM=rs232_pickit2)
void main()
{
int16 an=0;
setup_adc_ports(AN0|VSS_VDD);
setup_adc(ADC_OFF);
setup_spi(FALSE);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_256);
setup_oscillator(OSC_8MHZ);
while(true){
set_adc_channel(0);
delay_us(50);
an = read_adc(); // 0 à 1024
fprintf(rs232_pickit2,"AN %lu\r\n",an);
delay_ms(500);
}
} |
but I don't understand why it does not work :
I just receive "AN 16384".
do you have any idea about my problem?
thanks for your reply
Spilz |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Oct 30, 2012 2:43 am |
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What does your code do?
What does it not do?
Can you do a LED flasher?
Are you working with real hardware and not simulation?
Mike |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Oct 30, 2012 2:49 am |
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Er.....
What do you think:
setup_adc(ADC_OFF);
Does?.....
You are turning off the clock that operates the ADC. Saves power, but it can't then work....
setup_adc(ADC_CLOCK_DIV_8);
Is correct for your chip at 8MHz.
Best Wishes |
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spilz
Joined: 30 Jan 2012
Posts: 219
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| Posted: Tue Oct 30, 2012 2:50 am |
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Hi,
thanks for your interrest 
I'm using a developing board (real one), with adj resistor connect on pin_a0.
My code do more stuff like read I2C EEPROM, print on LCD modul. These parts works well.
So now I try just to read ADC, and it does not work...
I check with oscilloscop, the tension change on the pin_A0 when I turn the Adj resistor.
Any idea?
I already used ADC on 12F675, and it worked well... |
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spilz
Joined: 30 Jan 2012
Posts: 219
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| Posted: Tue Oct 30, 2012 2:58 am |
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thank Ttelmah,
changing
| Code: | | setup_adc(ADC_OFF); |
by
| Code: | | setup_adc(ADC_CLOCK_DIV_8); |
seems to be the solution : it work well now
so, problem solved, the solution is :
don't forget to configure ADC clock |
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