8-bit MicrocontrollersのトピックRe: ADC, help me

ADC, help me

KingJames — Mon, 19 Apr 2010 19:38:23 GMT

Hi all

I'm starting with Freescale Beekit Tool kit. I'm using IAR Embedded Workbench with MC1322x Sensor Node.

Someone can tell me how to use ADC or where I can find some example where I can understand...

Thanks...

Re: ADC, help me

Iko — Fri, 23 Apr 2010 00:51:12 GMT

Hi kingJames.

First, you must know the ADC channel where you want to make a convert.

After, you must define you're parameters:

-8,10,12.. bits results

-single or continus conversion

-whit or whitout interruption...

-ADC frequency (source clock and diviser/prescaler)

Next, you write on the various ADC register...

See the data sheet of you're µC for more details for ADC device...

Re: ADC, help me

KingJames — Fri, 23 Apr 2010 16:02:31 GMT

Hi Iko,

Thanks for the reply...

this is my c code:

1) set of gpio

Gpio_SetPinFunction(gGpioPin31_c, gGpioAlternate1Mode_c);
Gpio_EnPinPuKeeper(gGpioPin31_c, FALSE);

2) ADC Setup

#include "ADC_Interface.h"

...

AdcConfig_t sAdc_Config;
AdcConvCtrl_t adcConvCtrl;
Adc_Init();
Adc_Reset();
(void)Adc_SetFifoCtrl(FIFO_DEEP);
Adc_DefaultConfig(sAdc_Config, 24000); // (1Mhz prescale clock, 300KHz ADC analog clock,
                                         //   10 us on time, 40 us conversion time,
                                         //   auto working mode, compare interrupt disabled,
                                         //   FIFO interrupt disabled)

(void)Adc_SetConfig(&sAdc_Config);
Adc_TurnOn();

adcConvCtrl.adcTmrOn = TRUE;
adcConvCtrl.adcChannels = 0;
adcConvCtrl.adcChannels |= (1 << gAdcChan1_c);
adcConvCtrl.adcTmBtwSamples = gTimeBetweenSamples_c; // 1s between samples
adcConvCtrl.adcSeqMode = gAdcSeqOnTmrEv_c; //Timer mode
adcConvCtrl.adcRefVoltage = gAdcBatteryRefVoltage_c;
(void)Adc_SetConvCtrl(gAdcPrimary_c, &adcConvCtrl);

3) problem : I'm tring to sample 1.5V of battery (AA) on channel 1, but the sampled value that I read from FIFO is greater ,for example 2130 ....

Where is the problem on my code?

Have you some example about it?

Thank you in advance...