Hi,I have a test project were i use the ADC SAR Seq available in the 4200M, i need to read three inputs, i decided to transfer the results of the conv...
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Hi,
I have a test project were i use the ADC SAR Seq available in the 4200M, i need to read three inputs, i decided to transfer the results of the conversions from the ADC to memory with DMA.
Each ADC channel have a specific register to save the conversion result, so as i have 3 inputs i needed three DMA channels to transfer the result of each input to memory, then trigger an interrupt on one DMA channel and do the conversion from counts to voltage, like so:
This is the main loop:
#include "project.h"
#include <stdio.h>
#include <stdbool.h>
volatile bool data_ready = false;
enum {
ADC_CHANNEL_0 = 0,
ADC_CHANNEL_1 = 1,
ADC_CHANNEL_2 = 2,
};
enum {
FORM_FEED_CMD = 0x0C,
};
struct adc_result {
char string[20];
float32 volts;
int16_t counts;
} adc_result;
CY_ISR_PROTO(DMA_Handler);
int main(void)
{
struct adc_result ADC_Data[ADC_SEQUENCED_CHANNELS_NUM];
size_t string_size = sizeof(ADC_Data[ADC_CHANNEL_0]) / sizeof(char);
DMA_Chn0_SetInterruptCallback(&DMA_Handler);
CyIntEnable(CYDMA_INTR_NUMBER);
CyGlobalIntEnable;
UART_Start();
UART_PutString("Test ADC -> DMA -> memory\r\n");
PWM_Start();
ADC_Start();
DMA_Chn0_Start((void*) ADC_SAR_CHAN0_RESULT_PTR, &ADC_Data[ADC_CHANNEL_0].counts);
DMA_Chn1_Start((void*) ADC_SAR_CHAN1_RESULT_PTR, &ADC_Data[ADC_CHANNEL_1].counts);
DMA_Chn2_Start((void*) ADC_SAR_CHAN2_RESULT_PTR, &ADC_Data[ADC_CHANNEL_2].counts);
ADC_StartConvert();
while (1) {
if ( true == data_ready ) {
UART_PutChar(FORM_FEED_CMD);
for (uint8_t channel = 0; channel < ADC_SEQUENCED_CHANNELS_NUM; channel++) {
ADC_Data[channel].volts = ADC_CountsTo_Volts(channel, ADC_Data[channel].counts);
snprintf(ADC_Data[channel].string, string_size, "CH %d: %.3f Volts\r\n", channel, ADC_Data[channel].volts);
UART_PutString(ADC_Data[channel].string);
}
data_ready = false;
}
}
}
CY_ISR(DMA_Handler)
{
data_ready = true;
CyDmaClearInterruptSource(DMA_Chn0_CHANNEL_MASK);
}
/* [] END OF FILE */
The test project seems to work but is it the most efficient way to implement it?
May be a waste of DMA channels but i will try to port this project to the 4L family and send the ADC conversion results to the PC via USB, so i need to keep the infinite loop of the main function almost empty for USB transactions i guess (haven't did a USB project before 
).
Any advice or feedback?
The project is attached, i used Creator 4.1
Carlos
PD: The new forum seems great 
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Aug 21, 2017
Solved
