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LOLIN D32 PRO

No BOOT Button

You need to supply an external temporary button to enable the WiFi switching option that the builtin BOOT button provides on the DevKit board.

Its pin is defined in include/bonogps_board_settings.h as WIFI_MODE_BUTTON

Serial2 PINs need to be assigned

This board does not have dedicated definitions for Serial2, so you need to pick a couple of PINs and assign them to the TX/RX function.

These pins need to be defined in include/bonogps_board_settings.h as RX2 and TX2

The recommended options (defined in bonogps_board_settings) are

  • RX2 -> GPIO_NUM_4 (aka IO4, pin 12)
  • TX2 -> GPIO_NUM_2 (aka IO2, pin 14)

pin out lolin d32 pro

Note: IO4 is used by the SD Card, so this might have to be changed if you use it.

Battery monitoring

GPIO_35 provides Battery voltage with an A2D conversion (check this tutorial).

This replicates the functionality of battery fuel gauge available on the Lipo Rider Plus, but printed directly on the header of the main page of the web configuration interface.

main page header

This is the simple function used to collect voltage

analogRead(GPIO_BATTERY) / 4096.0 * 7.445

Percentage is based on the common LiPo values as charged by its TP4054: linear scale from 3.3V (0%) to 4.2V (100%).

These are enabled by the preprocessing macro SHOWBATTERY

Turning on and off when on a battery

Since the battery is always attached, the easiest option is to use the EN pin by tying it to the ground. This disables the onboard voltage regulator ME6211 (check schematics)

External leds for WiFi and Active

If you fully enclose your device, you should have external LED's so show that the device is on and what type of WiFi mode.

  • pick a low power led (e.g. a 3mm red or yellow)
  • compute what resistance you need (suggested: Led Calculator)

Now let bonogps know using these macros

  • LED_ACTIVE_EXTERNAL : define it to the pin where the Active LED is connected
  • LED_WIFI : define it to the pin where the Active LED is connected

Complete example schematic

Considering

  • LED_ACTIVE_EXTERNAL defined as GPIO_NUM_14, with led at 20 mA so closest resistor off the shelf is 47 Ohm
  • LED_WIFI defined as GPIO_NUM_12, with led at 20 mA so closest resistor off the shelf is 47 Ohm
  • WIFI_MODE_BUTTON defined as GPIO_NUM_25, with temporary switch
  • external On/Off locking switch
  • LiPo battery

This is how the schematics looks like

Lolin d32 pro schematic

BN-220 is shown, but it doesn not matter - it could be any of the supported ones.

Fritzing source file