Giga R1 using all three I2C Busses

Hardware GIGA R1
1

Hi, I am new at using the giga. I would like to use all three I2C busses on this board to communicate to three groups of I2C sensors. So far I can only communicate to the default "wire" group. Can the giga r1 actually use all three busses in one program and how do I direct communications to the other two busses (wire1 and wire2)? Thanks very much

2

Hi, I'm using two of the three happily.

Use Wire1 and Wire2 as you would Wire to address the others (e.g. Wire2.begin()), or I2C_SDA / I2C_SCL, I2C_SDA1 / I2C_SCL1 and I2C_SDA2 / I2C_SCL2 pins if you plan to use mbed::I2C directly.

3

Thank you for the reply. Some sensors will have the same slave address, but on a different bus. Do I need to address the first group after the "Wire.begin", then the second group after the "Wire1.begin" and so forth? Sorry for the newbe questions.....

4

No problem, we've all been there.

Yes, each interface will need a begin() before using it. Typically you will begin() each interface in your setup and then write/request inside your loop.

Are you planning on using libraries to access your sensors? It's worth checking to see if they support the Wire interface as an argument - many are hardcoded for Wire so will need tweaking for Wire1, Wire2

5

Ahh, maybe the library is the issue. When I run test cases with "Wire1.begin" or "Wire2.begin" it continues to default to addressing the slave devices on bus 1.

I am using these libraries:
#include <Wire.h>
#include <Adafruit_TMP117.h>
#include <Adafruit_Sensor.h>

Is there a better library to use that supports the three busses?

Thanks very much!

6

To use Wire1 you need to change everywhere that uses Wire to use Wire1...

Many libraries allow you to pass in a pointer or reference to which of these objects and they keep a pointer to the right one and reference all of the methods using that pointer...

7

For example if you look at the Adafruit_TMP117 at the begin method:

bool begin(uint8_t i2c_addr = TMP117_I2CADDR_DEFAULT, TwoWire *wire = &Wire,
             int32_t sensor_id = 117);

You can pass it in on the begin method.
And it takes care of it...
like: sensor1.begin(TMP117_I2CADDR_DEFAULT, &Wire1);

8

The Adafruit suite is ideal if you're just starting out. Typically the constructor or begin() accepts a pointer to the I2C interface, defaulting to Wire.
e.g. bool begin(uint8_t addr = BME280_ADDRESS, TwoWire *theWire = &Wire);

for their 280 pressure sensor

p.s. only Wire.h needs to be added, Wire1 and Wire2 will be included

9

wow....... awesome, thank you...it is working.!!!

Adafruit_TMP117 sensor1;
Adafruit_TMP117 sensor2;
Adafruit_TMP117 sensor3;
Adafruit_TMP117 sensor4;
Adafruit_TMP117 sensor5;

// Array to store temperature values for each sensor
float temperatureValues[5];

void setup() {
Serial.begin(9600);
Wire.begin();
sensor1.begin(0x48,&Wire);
sensor2.begin(0x49,&Wire);
sensor3.begin(0x4A,&Wire);
sensor4.begin(0x4B,&Wire);
Wire1.begin();
sensor5.begin(0x48,&Wire1);