hi there
ive been doing some testing using an Adafruit ADS1115. However, as i want to use it on a raspberry pi with coding in C, i’m avoiding using the Adafruit library. I found some code online which is a useful starting point to get my head around the registers etc.
/*
Read pot on AIN1 convert value to voltage
then display on Arduino serial monitor.
By Lewis Loflin lewis@bvu.net
http://www.sullivan-county.com/main.htm
Electronics website:
http://www.bristolwatch.com/index.htm
*/
#include <Wire.h> // specify use of Wire.h library
#define ASD1115 0x48
unsigned int val = 0;
byte writeBuf[3];
byte buffer[3];
float t_micro;
const float VPS = 4.096 / 32768.0; // volts per step
void setup() {
Serial.begin(115200);
Wire.begin(); // begin I2C
// ASD1115
// set config register and start conversion
// ANC1 and GND, 4.096v, 128s/
writeBuf[0] = 1; // config register is 1
// writeBuf[1] = 0b11010000; // 0xC2 single shot off <== NEW - single conversion/ AIN1 & GND/ 6.144V/ Continuous (0)
writeBuf[1] = 0b11010010; // 0xC2 single shot off <== ORIGINAL - single conversion/ AIN1 & GND/ 4.096V/ Continuous (0)
// bit 15 flag bit for single shot
// Bits 14-12 input selection:
// 100 ANC0; 101 ANC1; 110 ANC2; 111 ANC3
// Bits 11-9 Amp gain. Default to 010 here 001 P19
// Bit 8 Operational mode of the ADS1115.
// 0 : Continuous conversion mode
// 1 : Power-down single-shot mode (default)
//writeBuf[2] = 0b10000101; // bits 7-0 0x85 //8 SPS
//writeBuf[2] = 0b10000101; // bits 7-0 0x85 //128 SPS
writeBuf[2] = 0b11100101; // bits 7-0 0x85 //869 SPS
// Bits 7-5 data rate default to 100 for 128SPS
// Bits 4-0 comparator functions see spec sheet.
// setup ADS1115
Wire.beginTransmission(ASD1115); // ADC
Wire.write(writeBuf[0]);
Wire.write(writeBuf[1]);
Wire.write(writeBuf[2]);
Wire.endTransmission();
delay(500);
} // end setup
void loop() {
buffer[0] = 0; // pointer
Wire.beginTransmission(ASD1115); // DAC
Wire.write(buffer[0]); // pointer
Wire.endTransmission();
Wire.requestFrom(ASD1115, 2);
buffer[1] = Wire.read(); //
buffer[2] = Wire.read(); //
Wire.endTransmission();
// convert display results
val = buffer[1] << 8 | buffer[2];
t_micro = micros();
if (val > 32768) val = 0;
Serial.print(t_micro/1000000.0,6);
Serial.print("\t");
Serial.print(val * VPS);
Serial.print("\t");
Serial.println(val);
} // end loop
My question is this. How do you set up the ADC so you can measure 4 single ended inputs? I understand most of what is being done to the config register, but not the declaring inputs.
[/code] writeBuf[1] = 0b11010010; // 0xC2 single shot off <== ORIGINAL - single conversion/ AIN1 & GND/ 4.096V/ Continuous (0)
// bit 15 flag bit for single shot
// Bits 14-12 input selection:
// 100 ANC0; 101 ANC1; 110 ANC2; 111 ANC3
// Bits 11-9 Amp gain. Default to 010 here 001 P19
// Bit 8 Operational mode of the ADS1115.
// 0 : Continuous conversion mode
// 1 : Power-down single-shot mode (default)[/code]
How would you go about configuring all the inputs so you can use all 4 pins? From what i can see this code is only selecting ‘ANC1’. Is this as a reference point or do you have to repeatedly configure the register each time?
Any help would be greatly appreciated
Thanks
Ross