- VIN - This is the power input. Can be 3.3-5VDC, USE A POWER SOURCE THAT CAN HAPPILY SUPPLY 250mA, we will regulate this down to 3.3V safely! This is probably a VBAT or USB pin not a 3.3V regulated output.
- 3vo - The output from the onboard 3.3V regulator, you can use up to ~50mA for other devices if you want to power them from the same chip
- GND - Power and logic ground.
To keep transfers speedy, we use SPI not UART Serial. Serial is too slow and hard to synchronize. This uses more pins but the experience is much better!
Classic SPI Pins:
- SCK - SPI Clock from your microcontroller, level shifted so can be 3-5V logic
- MISO - SPI Data from the AirLift to the microcontroller, this is 3.3V logic out, can be read by 3-5V logic. This is tri-stated when not selected, so you can share the SPI bus with other devices.
- MOSI- SPI Data to the AirLift from the microcontroller, level shifted so can be 3-5V logic
- CS - SPI Chip Select from the microcontroller to start sending commands to the AirLift, level shifted so can be 3-5V logic. Also used to choose WiFi or BLE on reset.
Required Control Pins:
- BUSY - this pin is an input from the AirLift, it will let us know when its ready for more commands to be sent. This is 3.3V logic out, can be read by 3-5V logic. This pin must be connected.
- !RESET - this pin is an output to the AirLift. Set low to put the AirLift into reset. You should use this pin, even though you might be able to run for a short while without it, it's essential to 'kick' the chip if it ever gets into a locked up state. Level shifted so can be 3-5V logic
Optional Control Pins:
- GP0 - this is the ESP32 GPIO0 pin, which is used to put it into bootloading mode. It is also used if you like when the ESP32 is acting as a server, to let you know data is ready for reading. It's not required in WiFi mode, so you can leave it disconnected. But you'll need to connect it for BLE mode.
- RXI & TXO - Serial data in and Serial data out, used for bootloading new firmware, and for communication when in BLE mode. Leave disconnected if not using BLE or when not uploading new WiFi firmware to the AirLift (which is a rare occurrence).