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