I2C with Teensy 4.1

[hannahgill12]

Hello! I am trying to connect my Teensy 4.1 to my Raspberry Pi via I2C. I tried using the I2C_Scanner to find the Teensy's I2C address, but it did not work:


// --------------------------------------
// i2c_scanner
//
// Version 1
// This program (or code that looks like it)
// can be found in many places.
// For example on the Arduino.cc forum.
// The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
// Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 26 2013
// V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
// by Arduino.cc user Krodal.
// Changes by louarnold removed.
// Scanning addresses changed from 0...127 to 1...119,
// according to the i2c scanner by Nick Gammon
// http://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
// As version 4, but address scans now to 127.
// A sensor seems to use address 120.
//
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//

#include <Wire.h>


void setup()
{
Wire.begin();

Serial.begin(9600);
Serial.println("\nI2C Scanner");

// pinMode(40, OUTPUT); // iCS3 tester debug to set relay on RTC
// digitalWrite(40, HIGH);
}


void loop()
{
byte error, address;
int nDevices;

Serial.println("Scanning...");

nDevices = 0;
for(address = 1; address < 127; address++ )
{
// The i2c_scanner uses the return value of
// the Write.endTransmisstion to see if
// a device did acknowledge to the address.
Wire.beginTransmission(address);
error = Wire.endTransmission();

if (error == 0)
{
Serial.print("I2C device found at address 0x");
if (address<16)
Serial.print("0");
Serial.print(address,HEX);
Serial.println(" !");

nDevices++;
}
else if (error==4)
{
Serial.print("Unknow error at address 0x");
if (address<16)
Serial.print("0");
Serial.println(address,HEX);
}
}
if (nDevices == 0)
Serial.println("No I2C devices found\n");
else
Serial.println("done\n");

delay(5000); // wait 5 seconds for next scan
}


Also, I have some old code that uses the #include <i2c_t3.h> library. I'm thinking I will need to update this library for use with the 4.1. Is this the correct library to use now?
https://github.com/Richard-Gemmell/teensy4_i2c

Thank you,
Hannah

 

[PaulS]

I tried using the I2C_Scanner to find the Teensy's I2C address

When you run the I2C_scanner program on the Teensy, you won't find its I2C address because the Teensy acts as the I2C host. The I2C scanner only detects I2C slaves.

Regards,
Paul

 

[hannahgill12]

This makes so much sense. Thanks Paul. I got it working with the following steps:

In order to work I2C with the Teensy 4.1 series (4.0 and 4.1), there is an updated library available on GitHub at this location: https://github.com/Richard-Gemmell/teensy4_i2c

This library will import in your code as:

#include <i2c_driver.h>
#include <i2c_driver_wire.h>

And will entirely replace the #include <Wire.h> library.

Thanks for making this library Richard!