- GND - Common power/logic ground.
- 3.3V - Power supply for the ublox WiFi module. You'll need up to 250mA to power the module. ItsyBitsy's tend to have a 500mA regulator so they should be OK, just make sure you're aware of your power budget
To keep transfers speedy, we use SPI not UART Serial. UART 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, logic level is 3.3V only
- MISO - SPI Data from the AirLift to the microcontroller, logic level is 3.3V only. 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, logic level is 3.3V only.
- ESPCS - SPI Chip Select from the microcontroller to start sending commands to the AirLift, and to choose BLE mode on reset, logic level is 3.3V only
Required Control Pins:
- ESPBUSY - 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. This pin must be connected.
- ESPRST- 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. Logic level is 3.3V
Optional Control Pins:
- ESPGPIO0 - this is the ESP32 GPIO0 pin, which is used to put the WiFi module it into bootloading mode if you want to update the firmware. 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, but you'll need to connect it for BLE mode. You'll need to solder the pad on the bottom of the Bitsy Add-on to connect it.
- ESPRX & ESPTX - 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). You'll need to solder the two pads on the bottom of the Bitsy Add-on to use these pins. Soldering the pads connects ESPTX to RX and ESPTX to RX, respectively.
There is a small RGB LED to the left of the ESP32. These RGB LEDs are available in the Arduino and CircuitPython libraries if you'd like to PWM them for a visual alert. They're connected to the ESP32's pins 26 (Red), 25 (Green), and 27 (Blue).