main.cpp

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#include <Arduino.h>
#include <SPI.h>
 
#include "STAR_ADS126X.h"
 
// Change the following line to automatically use the correct pins for the board
// being tested (PT_Board, LC_Board, RTD_Board, or TC_Board)
#define PINS_ACTIVE_LAYOUT sense_board_pins::PT_Board
 
// These lines MUST be after the #define PINS_ACTIVE_LAYOUT or they will
// overwrite it with the default value!
#include "connector_adc_map.h"
#include "sense_board_pins.h"
 
// Pin on each connector to test (always 1)
#define TEST_PIN 1
 
using namespace sense_board_pins;
 
static ADS126X ads126x;
 
// Buffer configuration
// Magic (4 bytes) + 83 samples × 3 channels × (4 bytes timestamp + 4 bytes
// reading) = 1996 bytes
#define BUFFER_SIZE 1996
#define MAGIC_SIZE 4
#define SAMPLES_PER_BUFFER 83
#define NUM_CHANNELS 3
 
static uint8_t txBuffer[BUFFER_SIZE];
static const uint8_t MAGIC[MAGIC_SIZE] = {'A', 'D', '2', '6'};
 
void setup() {
    Serial.begin(115200);
 
    // Setup SPI
    SPI.begin(Pins.ADC_SCLK, Pins.ADC_MISO, Pins.ADC_MOSI, Pins.ADC_CS_1);
 
    // Due to the ADC output having valid data on FALLING CLK edges
    SPI.setDataMode(SPI_MODE1);
    pinMode(Pins.ADC_DRDY_1, INPUT);
 
    // Setup ADC
    ads126x.begin(Pins.ADC_CS_1);
 
    // Stop it while we config it, as suggested by datasheet
    ads126x.stopADC1();
 
    // Bypass the PGA, so it does not affect measurements
    ads126x.bypassPGA();
 
    // Set the filter. You can change this to try different filters
    ads126x.setFilter(ADS126X_SINC4);
 
    // Set the datarate. You can change this, but the options depends on the
    // filter
    ads126x.setRate(ADS126X_RATE_1200);
 
    // Start ADC now that configuration is done
    ads126x.startADC1();
 
    // Initialize buffer with magic bytes
    memcpy(txBuffer, MAGIC, MAGIC_SIZE);
}
 
void loop() {
    // Pointer to data section (after magic bytes)
    uint8_t* dataPtr = txBuffer + MAGIC_SIZE;
 
    // Collect 83 samples to fill the buffer
    for (int sample = 0; sample < SAMPLES_PER_BUFFER; sample++) {
        // Loop through connectors 1, 2, 3
        for (int connector = 1; connector <= NUM_CHANNELS; connector++) {
            // Set the mux for this connector
            ads126x.setInputMux(getAdcChannel(connector, TEST_PIN),
                                ADS126X_AINCOM);
 
            // Wait for DRDY pin (allow settle time after mux change)
            while (digitalRead(Pins.ADC_DRDY_1) != LOW) {
                delayMicroseconds(10);
            }
 
            delayMicroseconds(25);
 
            // Capture timestamp right before reading
            uint32_t timestamp = micros();
 
            // Get the reading
            const auto reading = ads126x.readADC1();
            int32_t readingValue = reading.value;
 
            // Store timestamp (little-endian format)
            *dataPtr++ = (timestamp >> 0) & 0xFF;
            *dataPtr++ = (timestamp >> 8) & 0xFF;
            *dataPtr++ = (timestamp >> 16) & 0xFF;
            *dataPtr++ = (timestamp >> 24) & 0xFF;
 
            // Store reading (little-endian format)
            *dataPtr++ = (readingValue >> 0) & 0xFF;
            *dataPtr++ = (readingValue >> 8) & 0xFF;
            *dataPtr++ = (readingValue >> 16) & 0xFF;
            *dataPtr++ = (readingValue >> 24) & 0xFF;
        }
    }
 
    // Send the complete buffer
    Serial.write(txBuffer, BUFFER_SIZE);
}