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For Wifi module
There is no space on the seeeduino for any extras :(
WIFI Module
Decided Deciding to keep it off board. this keeps it consistent with the GPS module. One SPI connector for thisthis on board (removable via headers) to make integration easy and reliable. The board we use (Overview | Adafruit AirLift - ESP32 WiFi Co-Processor Breakout | Adafruit Learning System) needs SPI and two more pins, so it won’t fit a standard Pixhawk connector anyways.
Barometer
ICP-20100 TDK InvenSense | Sensors, Transducers | DigiKey
Plopping this here for now since it is what the pixhawk uses but it is probably too small and I have to check with EFS to make sure they are cool with it using I2C (since we are out of pins on the seeeduino and I2C is the only one where we can just throw it in the existing bus).
EFS doesn’t seem to care too much about it. I think the play is to not add it on board and just use the extra I2C connector if we need one and connect it to an external baro breakout board. This also allows us to defer the job of breaking out the IC to someone else so this board is easier to solder and more reliable.
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Not doing this since it is just a nice to have and we do not have more pins for another serial port.
Seeeduino
Turns out the Seeduino does not even have enough pins for the bare minimum of what we need. Checking with EFS to see if we can just use a different board with more pins. An Arduino nano does not have enough memory but there are ESP32 versions that are beefier and since it has WIFI built in we could maybe ditch the WIFI module as a whole and free up more pins. Or, we can get the ESP32 version of the Seeeduino and do the same thing.
Looks like this is all scrapped since it won’t have enough pins but will keep here for reference since some of the research will be used still:
Using this variant for the headers so it is removable:
102010388 Seeed Technology Co., Ltd | Development Boards, Kits, Programmers | DigiKey
So the datasheet on digikey looks like something I’d see in an electronics kit tutorial I would do middle school so I had to look elsewhere for the footprint. For reference and to brighten up your day, here is the one of the first files you see in the datasheet zip 💀:
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I will be going off the datasheet I found here on another website: Seeed-Studio-XIAO-Series-SOM-Datasheet.pdf (seeedstudio.com) and Seeed-Studio-XIAO-Series-Package-and-PCB-Design.pdf (seeedstudio.com) for the pad layout.
The seeeduino with headers has 7 adjacent header pins on either side. For the female header sockets, these should do PPPC071LFBN-RC Sullins Connector Solutions | Connectors, Interconnects | DigiKey. I plan to mount them in the correct place for the seeeduino and then have another set just mounted outside of that for EFS to use for debugging. Female headers should be best for that anyways since they are more protected.
The 5V pin is connected the Vin solder pad internally, so the 5V pin can be used to power the seeeduino. However, a diode should be placed on the Vin to make sure connecting a usb port to the seeeduino won’t send current into the battery. The forward voltage drop should be fine since the seeeduino can run on 3.3V. The average operating current is 14.5mA but looking at the datasheet of the chip inside, SAM D21/DA1 Family Data Sheet (microchip.com), the maximum draw could be up to 96 mA. For a good safety factor, I’ll make sure the diode can handle 200mA.
Nathan’s seeeduino tracking antenna board is here for reference hardware/Projects/Arduino_AAT at master · UWARG/hardware (github.com).