external ADC

DKH · Guest

Does anyone here have an example how to conect and program an external ADC(for example ADC0804)?

tks

Nina

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

Start with EX-AD12.C in your examples folder. It uses either the LT1298 or the MCP3208 converters, but it is a place to start.
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nina · Joined: 20 Apr 2007 Posts: 111

thanks SherpaDoug....do you have any example showing how to conect and program this devices?

tks

Nina

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

One question would be, why do you want to use an external 8-bit A/D
chip when your PIC likely has an internal 10-bit A/D ?

nina · Joined: 20 Apr 2007 Posts: 111

PCM programmer..

My load cell has 10000 lbs (at full load) if I have a 10 bits ADC I just have 1024 reading then I would have reading like...10, 20, 30,40,50...100,110,120,130...until 10000 lbs. I need more precision thats why I need use an external ADC

tks

nina

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

You need to read posts like this one:
http://www.ccsinfo.com/forum/viewtopic.php?t=30517
Your problem is not really how to do the interface, it's how to do the
PCB layout so the noise is kept at a very low level.

Humberto · Posted: Tue May 01, 2007 9:32 pm

nina · Joined: 20 Apr 2007 Posts: 111

sorry humberto...I missed when I sad ADC0804. I intend use a ADC (at least 16 bits resolution).

Thanks for explanation about how to conect external ADC, I will check and if I have some doubt I will post here.

About programming PIC to get reading from external ADC. Do I just need do this or do I need something else?

setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
delay_ms(5);
printf("-------Ready to read-----");

while (TRUE)
{

set_adc_channel(0);
delay_us(20);
valor1=read_adc();
delay_us(30);
printf(")%4.0f ->%1.2f :::",valor1,volt1);
printf(lcd_putc,"%2.2f",valor1);
}

Tks

nina