multiple i2c buses, nano

Development Boards Artemis
1

Hello, I am fairly new to using redboards. I have a redboard Artemis Nano. the site says there are 4 i2c buses on the board (including the QUIC connector). I was wondering if anyone knows of a guide, example, video, tutorial etc… on how to use more than one i2c bus? It seems obvious, but I have not found too much help.

BTW, the reason is I have two sensors with the same i2c address, so to use them both I would like to use the QUIC connector and a second i2c bus.

THANKS!

2

Declare a new wire port using the IOM instance that you want like this:

TwoWire myWire(N);

Choose N depending on which pins you want to use (there are 3 options that aren’t on the qwiic connector) for example pins 9 and 10 on the Nano are connected to IOM# N=4

https://cdn.sparkfun.com/assets/5/5/1/6 … s-Nano.pdf

Then you use “myWire” just like you would the normal “Wire”

3

As of the latest 2.2.1 core (today 4/20/22) this takes two arguments, which are the SDA and SCL pins (not a single device number). Compiling and running the code causes a hard fault. The other method that I used in the past on a Redboard Thing was to reference an external pre-defined Wire1() object as my second i2c device. The result of that technique on Nano is also a hard fault.

4

I’m getting the same hard faults and I can’t find any documentation on how to fix it. Anyone have an update on this?

5

SPI and I2C (or Wire) are driven by an Input Output Module (IOM) in the Apollo3. Unlike some other processors, the pins for each IOM can only be assigned to a fixed pad (processor connection point) . If the SCL / SDA combination is not as indicated belowfor a Nano, you will get an hard error:

IOM SDA-PAD  SCL-PAD   NANO-PIN (SDA) NANO-PIN (SCL)
0    6        5           11 (sck)     13 (MISO)    pins assigned to SPI
1    9        8                                     NOT CONNECTED on the NANO
2    25      27           QWIIC         QWIIC       Wire
3    43      42            7 (SDA3)     6 (SCL3)    Wire1
4    40      39           10 (RX1)      9 (TX1)     pins assigned to Serial1
5    49      48                                     Serial / USB

If you do NOT use SPI OR do NOT use Serial1 you can try re-assign to Wire-interface on the Nano.:
#include “Wire.h”
In case of SPI re-assign : arduino::MbedI2C MyWire(6, 5);
In case of Serial1-re-assign: arduino::MbedI2C MyWire(40, 39);

6

my issue was solved by moving the #include <Wire.h> statement up to the top of my code. I’m writing my code to work with both arduino and artemis with some #if compiler directives, so maybe that had something to do with it.

Old code (broken):

//#define Arduino
#define Artemis

#ifdef Arduino
  #define I2C Wire
#endif
#ifdef Artemis
  #define I2C Wire1
#endif

#include <Wire.h>

void setup() {
  I2C.begin();
}

// and so on

New code (working):

#include <Wire.h>

//#define Arduino
#define Artemis

#ifdef Arduino
  #define I2C Wire
#endif
#ifdef Artemis
  #define I2C Wire1
#endif

void setup() {
  I2C.begin();
}

// and so on