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RA835AI Rasberry Pi "HAT" for Stratux
This board is designed for DEVELOPMENT PURPOSES ONLY. It is not intended for use in flight or in an airplane. Use this board at your own risk!
This is a really rough draft of a "HAT" (Hardware Attached on Top) to connect a RA835AI to the Rasberry Pi for use primarily with Stratux.
Currently it is just a starting point. Some things yet to work out:
- Is FSYNC supposed to be grounded? Data sheet says yes; forums leave doubt.
- Pull-ups for I2C? - not necessary, as I understand that the Pi itself has 1.8k pullups
I tried by best to keep the ground planes clear of traces so that hopefully it shields the GPS module from the Pi processor underneith.
This uses a custom library for the RA835AI, and a contributed library from www.cadsoftusa.com "raspberrypi_bastelstube_v13" for the Pi GPIO connector and board layout.
- 0.1 - Initial commit
- 0.2 - Added C1 and C2 decoupling capacitors. 0.1uF (P-tolerance=+100% ,-0%) and 10uF values recommended by on the RY835AI data sheet. Added a cut-trace jumper to disconnect FSYNC from GND if desired.
- 0.3 - Keepout area added underneith GPS antenna area. Pads around mount points reduced and made round to make room for signal traces.
- 0.4 - Added "PWR IN" circut -- see page 14 Added FAN output controlled by GPIO4. (minor change to explicitly list R1's value as 10k)
- 0.5 - Modified fan control signal to use GPIO18 rather than GPIO4. This is consistent with currently used AHRS boards. This revision has not been manufactured or tested, so make sure to ERC/DRC and double check if you decide to have this made.