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Dear SparkFun Community,

I made some glorious tests with the 9DoF Razor IMU, perfect logging for acceleration data and writing to SD works really good.

Now I want to expand my 9DoF Razor IMU with some Sparkfun I2C Sensors and put them on wire to the I2C Ports of Razor´s (SCL/SDA/3.3V/GND). I bought the RV-1805 RTC Clock, the environmental combo breakout BME280 CCS811 and the Ambient Light Sensor Breakout - APDS-9301.

The problem is that I can´t get any communication by using the example code used in the hookup guides. The serial monitor doesn't give any output. But in every hookup guide the RedBoard used for manage the communication. I also bought a RedBoard Qwiic and it works perfekt. The output is just as expected with RedBoard Qwiic

But like I said before, I want to use the 9DoF Razor IMU for manage the communication because I want to log to SD and use a Battery which make the 9DoF Razor IMU so perfect in this case.

Could you please give me an example how I can expand the 9DoF Razor IMU by using the basic firmware to still log the acceleration and write to SD and as addition use another Sensor over I2C?

In the hookup guide of 9DoF Razor IMU is an picture where the BME 280 is used like I would use it. But I can´t find any example code for this combination of the two boards. ... okup-guide


Thank you very much in advance for your help.

best wishes from Toby
Hi Toby,

While we do not have any examples available for a plug-and-play option here, you should be able to use the example code for the two I2C breakouts you are trying to use with this board with some simple modifications. The issue here is the SAMD21 handles Serial.print() functions differently than AVR-based Arduinos like the RedBoard Qwiic. This example from the SAMD21 Dev and Mini Hookup Guide goes over that in some more detail and this tutorial will go into a lot more detail on how to customize the SERCOM ports on a SAMD21 microcontroller if you want to learn more about that IC. The "Using the MPU-9250 DMP Arduino Library section of the 9DoF Razor's Hookup Guide has some information about how the stock firmware for the 9DoF Razor prints serial data.

Essentially, you need to define which serial port you are sending the data from your sensors out over so if you want to pipe the data from your RTC breakout via USB, you will need to adjust all your Serial calls in the code to SerialUSB.

I hope this helps explain the issue and gets you pointed in the right direction to modify the code to print serial data from the extra sensors you want to use in your project. Let us know if you have any other questions or issues about the 9DoF Razor and we would be happy to help as much as we can.