In this blog post I will be talking about my progress in getting the I2C interface working with the Nicla Sense ME board.
I have proceeded by soldering the male connectors to the Nicla board and the sensors used, which are: Adafruit SI1145, Adafruit MEMS Microphone Breakout, MLX90614 and Gravity Heart Rate Sensor.
Here the connectors needed can be seen (Note: I did not add full headers, as these connectors will be removed at a later stage, and by only adding connectors to what is needed, it will make my life easier after):
Here I was checking some of the voltage outputs on some of certain pins, as in the datasheet it does not specify the exact voltage output:
VBAT is outputting 5.0 volts with the ground and it depends on battery power;
VIN is for powering the board, between 3.5v and 5v needed. However, if the VIN is connected to a battery, and the USB is connected as well, the Board cannot be programmed/no serial output.
VDDIO_EXT is a programmable pin and is used as reference for analogReads (to map the maximum voltage from the sensor to the maximum possible, 0-1023 values);
The following sensors use I2C:
Adafruit SI1145
MLX90614
The following sensors use Analog Outputs:
Gravity Heart Rate Sensor
Adafruit MEMS Microphone Breakout
After writing some code and using the test code from the libraries needed for each sensor, I realised that digitalRead and analogRead work fine, but I2C does not. I was not able to get any sensor to be recognised through I2C on the Nicla Sense ME, which means that I am either doing something wrong (As there isn't much documentation) or the I2C is write only to other devices, which would be strange.
I have then proceeded to test the sensors with the Arduino MEGA I have, with the sensors powered with 3.3v for consistency, and everything was working perfectly, as can be seen:
I have proceeded to create a request to the official Arduino support as well as creating an entry on the Bosch Sensortec Community to see if any Developer/Representative can offer any advice as the I2C may require certain nameclasses or a specific method for calling.
The good news is that I tested all the sensors with the Mega and they all seem to be outputting accurate values, all seem to work with 3.3 volts while using the default libraries which can be loaded to the Nicla Sense ME.