72 lines
3.2 KiB
C++
72 lines
3.2 KiB
C++
#include <Adafruit_ADS1X15.h> // https://github.com/adafruit/Adafruit_ADS1X15, with partially its "continuous" example code integrated in ths
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#define WAIT_TIME 1000UL // default wait time each value read
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#define ADS_MAX 4 // # of analog input pins of an ADS1115
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#define VOLTAGE_RANGE 6.144f // ADS1115 default gain (+/- 6.144V). Change this number smaller will reduced its actual magnutude, and vice versa
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#define CONST_I2C 32768 // a constant value
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#define ADC1_ADDR 0x48 // Address (identifyer) for the first ADS1115 chip. We might gonna have up to four of those connected in one I2C line
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#ifndef IRAM_ATTR
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#define IRAM_ATTR
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#endif
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Adafruit_ADS1115 adc;
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unsigned long currTime; // non-blocking timer
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int channel = 0; // mux selector for which channel (AIN0-AIN3) to read the analog value from. See ADS1115 datasheet for details
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float adcReadings[ADS_MAX]; // buffer to hold all values read from an adc
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constexpr int READY_PIN = 3; // pin # that connects the "ALRT" pin of the ADS1115 to the board
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volatile bool new_data = false; // "ready" flag for the ADS1115
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/**************************************************************************/
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/*!
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@brief parse data from the ADS1115 and record to the buffer array
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Upon data recieved, call getLastConversionResults() once to record the
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value into the adcReadings array. Increment/cycle back the channel mux
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selector and call startADCReading() to read the next channel. set back
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the new_data flag back to false
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@acknowladgement https://github.com/RobTillaart/ADS1X15/blob/master/examples/ADS_continuous_4_channel/ADS_continuous_4_channel.ino
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*/
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/**************************************************************************/
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void readData() {
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// we only wanna grab/set data if the ADS is ready to
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if (new_data) { // TODO: for some reason some board get the channel index off
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// save the value
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adcReadings[channel] = adc.getLastConversionResults();
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channel = (channel + 1) % ADS_MAX; // request next channel #. Cycle back to zero if the number is larger than ADS_MAX (maybe must multiple of 2)
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adc.startADCReading(MUX_BY_CHANNEL[channel], true);
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new_data = false; // toggle back the flag
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}
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}
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void IRAM_ATTR NewDataReadyISR() { // interrupt to make it read data
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new_data = true;
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}
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void setup() {
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Serial.begin(19200);
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adc.begin(ADC1_ADDR, &Wire); // initialize one ADS1115 on approprate address
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pinMode(READY_PIN, INPUT);
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// "Ready" when on falling signal edge (negedge)
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attachInterrupt(digitalPinToInterrupt(READY_PIN), NewDataReadyISR, FALLING);
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adc.startADCReading(MUX_BY_CHANNEL[channel], true); // read once
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currTime = millis(); // record the current time
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}
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void loop() {
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readData(); // always read data from the ads1115
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if (millis() - currTime >= WAIT_TIME) { // non-blocking time delay, giving ADC and everything else enough time to update
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// print the array, as we don't have internal method for it.
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Serial.print("[");
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for (int i = 0; i < ADS_MAX; i++)
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{
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Serial.print(adcReadings[i] * VOLTAGE_RANGE / CONST_I2C);
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if (i != ADS_MAX - 1) { // fence-post the array print
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Serial.print(", ");
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}
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}
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Serial.println("]");
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currTime = millis(); // reset the current time
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}
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}
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