Pyxida Revision 5 Known Errors

CC1120 Radio

• Wrong capacitor used in power supply causes brownouts when putting chip in send or receive mode. Higher resistance on the capacitor causes brownouts.
• There is also possibly a problem in the schematic that requires a trace to be cut. It is referenced in the following thread https://e2e.ti.com/support/wireless_connectivity/proprietary_sub_1_ghz_simpliciti/f/156/t/682837

Barometer

• The BMP280 barometer has not showed up on I2C scanning tools. This suggests that all barometer chips provided were bad or that the BMP280 is not staying in I2C communication mode. That is because the BMP280 switches to SPI mode if the SDO pin is not held high at power-up. We may want to test this by switching the BMP280 chips on the board with those on a breakout board that we can confirm work beforehand.

Screw Terminals

• The screw terminals we put on revision 5 are great for testing but won’t hold up during flight. We should replace them with traditional screw terminals.

Flash Memory

• Two of the flash chips now seem to have partially failed to the point where they are still accessible via software but unusable for flight. 
• Current theory is that this might have been because of x-ray irradiation from airport security.
• In the future, it may be a good idea to check if purchased flash chips are robust against airport security scanners or to find some way to protect them.