altimeter makings

[the random rocketer]

I just ran into this on Adafruit. BNO055 + BMP280 https://www.adafruit.com/product/5937 Instant Altimeter. I just ordered mine so now I dare post this. It's damn small and saves one board on a typical make your own altimeter. Won't save any money making your own. But for those who want to code their own telemetry computer It's ideal.

 

[bdureau]

look cool, should make life easier for people who do not want to build their own board

 

[waltr]

Adafruit has a lot of great boards with sensors. I use them instead of making custom PCBs (which I have designed many).
My current Flight Data logger uses the Adafruit Accel, Gryo & Mag plus a BMP390 baro.
CPU is an ESP8266 on an Adafruit Huzzah board. Very simple to wire.

 

[Spacedog49Krell]

There are two BNO055 features that I do not like. The 14-bit accelerometers and the internal fusion functions are limited to the 4G accelerometer range. The BNO055 was designed for drones and pedometer applications. If the fusion function worked with the 16G range for Quaternion and Euler angles, it would be great for VOC applications.

For my latest flight computers, I mount the Adafruit microSD card BFF to the backside of a QTPY RP2040 or ESP32. Together with the ICM-20649 and BMP390 it makes for a quick, east to assemble flight computer for LPR and MPR projects. If I want to record data faster than 500Hz, I switch the microSD card BFF to an OpenLager and record data at 900Hz.

 

[the random rocketer]

Darn that kills the whole project. Any model rocket needs to hit 5g to have enough velocity off the rod. I do not want to code a Kalman filter from scratch. I have a 10 DOF Adafruit IMU board that I was thinking of using but the same argument applies. Also they're out of production which makes it harder for the next person to duplicate the design.

 

[waltr]

Read this thread:
https://www.rocketryforum.com/threads/actively-controlled-rocket-not-flying-straight.181787/

About the issues getting the BNO055 to actually work, which they haven't yet.
There are plots of the accelerometer data of flights and shows the accelerometer pegged at maximum during boost.

 

[Spacedog49Krell]

You can read the 16G range of the BNO055, but the BNO055 doesn't output Euler angles or quaternion vectors in that mode. There are simplified Euler and quaternion equations that can be used with M4 processors.

I did hear a rumor that Bosch is developing an IMU that will output Euler and quaternion with all the accelerometer ranges and not just the 4G range.