LilyGo-T-Relay change I2C pins

[rogeriocpe]

Good morning everyone,
I need help with the LilyGo-T-Relay board, I need to use I2C to communicate with the INA219, but I can't define the I2C pins. Can anyone help me?

[teastain]

@rogeriocpe As you probably know there does not seem to be a dedicated I2C port. Looking at the chip pinout here:
https://www.espressif.com/sites/default/files/documentation/esp32-wrover-b_datasheet_en.pdf
page 9, I would guess that GPIO 26 and 14 would work for I2C.
Maybe define them with wire.begin(26, 14);
I do not have a T-Relay to try this on!
Cheers, Terry

[rogeriocpe]

@teastain Thanks, but I still can't get it to work. I'll put the code here to see if I have something wrong.

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_INA219.h>

Adafruit_INA219 ina219;

//#define I2C_SDA 26
//#define I2C_SCL 14

void setup(void)
{
Serial.begin(115200);
while (!Serial) {
// will pause Zero, Leonardo, etc until serial console opens
delay(1);
}

Serial.println("Hello!");

Wire.begin(26, 14);

if(! ina219.begin()){
Serial.println("Failed to find INA219 chip");
while (1) { delay(10); }
}

Serial.println("Measuring voltage and current with INA219 ...");
}

void loop(void)
{
float shuntvoltage = 0;
float busvoltage = 0;
float current_mA = 0;
float loadvoltage = 0;
float power_mW = 0;

shuntvoltage = ina219.getShuntVoltage_mV();
busvoltage = ina219.getBusVoltage_V();
current_mA = ina219.getCurrent_mA();
power_mW = ina219.getPower_mW();
loadvoltage = busvoltage + (shuntvoltage / 1000);

Serial.print("Bus Voltage: "); Serial.print(busvoltage); Serial.println(" V");
Serial.print("Shunt Voltage: "); Serial.print(shuntvoltage); Serial.println(" mV");
Serial.print("Load Voltage: "); Serial.print(loadvoltage); Serial.println(" V");
Serial.print("Current: "); Serial.print(current_mA); Serial.println(" mA");
Serial.print("Power: "); Serial.print(power_mW); Serial.println(" mW");
Serial.println("");

delay(2000);
}

[teastain]

@rogeriocpe said in LilyGo-T-Relay change I2C pins:

INA219

oof, OK. Can you draw out the circuit and post it, or email it to me at:
teastain@me.com

[supermarioprof]

@teastain @rogeriocpe any progress?
I'm using T-relay 8X and would like to use INA219 too,
somewhere I've found I could use pins 32 and 33 but they are used by relays, so what?

I also tried to scan with common I2C scanner code, after connecting to pin 14 and 25, without success, no device found.

[teastain2]

@supermarioprof
So, you want to add a current sensor to your LilyGO T-Relay (8)?
https://www.lilygo.cc/products/t-relay-5v-8-channel-relay
Yes pins 32 and 33 are used by relays
You should be able to choose any two GPIO pins on that header!

https://github.com/Xinyuan-LilyGO/LilyGo-T-Relay/blob/main/Schematic/T_Relay8_ESP32.pdf

I would then try GPIO 14 and 15.
Wire.begin(26, 14); (SDA,SCL)

Cheers, Terry

[supermarioprof]

@teastain2 Bingo! that worked, changing
Wire.begin();
to
Wire.begin(26, 14);

so pinout for I2C on T-relay 8X is
SDA: pin 26
SCL: pin 14

thank you!