Challenger RP2040 WiFi/BLE Datasheet

The Challenger RP2040 WiFi/BLE is a small embedded computer equipped with a combined WiFi and BLE chip, in the popular Adafruit Feather form factor. It is based on an RP2040 micro controller chip from the Raspberry Pi foundation which is a dual core Cortex M0 that can run on a clock up to 133MHz.

For more information about the RP2040 you can look here.

We paired the RP2040 micro controller with a 8MByte high speed flash capable of supplying data up to the max speed. The flash memory can be used both to store instructions for the micro controller as well as data in a file system and having a file system available makes it easy to store data in a structured and easy to program approach.

The board can be powered from a Lithium Polymer battery connected through a standard 2.0mm connector on the side of the board. An internal battery charging circuit allows you to charge your battery safely and quickly. The device is shipped with a programming resistor that sets the charging current to 500mA. this resistor can be exchanged by the user to either increase or decrease the charging current, depending on the battery that is being used.

The combined WiFi and BLE section on this board is based on the Espressif ESP32C3 chip. The ESP32C3 is based on the RISCV processor core combined with a complex and powerful 2.4GHz radio block and 4MByte FLASH memory, making it a complete WiFi and BLE solution only requiring very few external components.

The ESP32C3 is connected to the micro controller using both a UART channel as well as an SPI channel and the operation is controlled using a set of standardized AT-commands.

Challenger 2040 WiFi isometric front view
Challenger RP2040 WiFi/BLE

Short introduction to the board

PCB
The board is based on a popular form factor called “Feather” which is created and maintained by an American company called Adafruit. The entire specification for the Feather format is available here. The size of the PCB for the module is 50.80mm x 22.86mm but the entire module is a little bit bigger as the Type C USB connector protrudes about 1 mm outside the board.

Antenna
On the opposite end from the USB connector the WiFi antenna is mounted. When mounting the board into any enclosure you should make sure to keep stuff like cables and/or walls from the enclosure away from the antenna as much as possible. Anything mounted in the vicinity of the antenna will affect its performance.

Headers
On each of the longer sides of the PCB there are holes intended for soldering pin header connectors. If you don’t want to use connectors for some reason you can also solder a wire directly into the hole, making a permanent connection to your external device. If you go this way please make sure that the wires are fixed in place, otherwise vibrations can cause the wire to brake at the soldering point.

LED’s
On each side of the USB connector there is a small indicator LED placed. The LED which is marked CHG is the charge control indicator. This red LED will shine whenever the connected battery is being charged, and when the battery is fully charged the LED will turn off again. If you haven’t connected a battery to the board this LED will not come on at all.

On the other side of the USB connector there is a user programmable green LED. This LED is connected to pin D13 and can easily be controlled by the user program.

Finally there is a neopixel LED on the board. This is an RGB LED with intensity control, run by a single GPIO (D14/GPIO11) pin on the board. There are several good example libraries that can be used to drive this LED.

Hardware details

Pins

The on board micro controller (RP2040) have a number of communication channels that have been routed out to the side (header connector) connectors.

  • UART – One UART channel have been routed to the header pins (RX, TX). The micro controller have 2 UARTs, on this board the second UART is used for communicating with the WiFi chip.
  • SPI – One SPI channel have been routed to the header pins (SCK, SDO, SDI).
  • I2C – One I2C channel have been routed to the header pins (SCL, SDA).
  • Analog pins – The micro controller have 4 analog input pins that all are available on the header pins (A0-A3).
  • PWM – All pins can be used for PWM.

The pin chart below shows the placement of all pins and their respective functions. When working in an Arduino environment (or Platform IO) use the blue pins when writing your code and when working with CircuitPython use the orange marked pin assignments.

Power

The board can be powered from multiple sources. The most obvious way to run the board is by plugging it in to a USB cable and attach it to your computer. In this mode you can write software and test the board with all its functionality.

There is also a third way to supply the board. This way is more invasive and will disable the onboard 3.3V power regulator.

You will have to pull the EN header pin low and then supply your own 3.3V voltage on the 3.3V header pin. Please note that when disabling the onboard power regulator you will have to supply the 3.3V also when running the system on battery power.

Battery

As described earlier the board can be powered from a LiPo battery. The battery can be connected using a standard 2.0mm JST connector through the battery connector on the right side of the board or ff the battery is an integral part of the system that you are designing it is possible to connect the battery through the BAT pin instead.

Switching between the battery voltage and the applied USB voltage or external 5V is done seamlessly by the on board circuitry.

Charging of the battery is done by either connecting a USB cable or by connecting a 5V power source to the header pin marked USB on the board. If you do this make sure you connect your voltage through a 1A schottky diode to avoid any excessive current draw in the system when the two levels are slightly different.

Please note that providing external charger circuitry could destroy the internal charger on the Challenger board.

Network controller

Connection between MCU and ESP32C3 WiFi controller.

The board uses the second UART (UART 1) of the MCU to connect to the ESP32C3 as well as two GPIO pins that allows the RP2040 to reset and put the ESP32C3 in flash mode. The pins used are as follows.

  • GPIO4 acts as UART1 TXD
  • GPIO5 acts as UART1 RXD
  • GPIO19 is connected to ESP32C3 reset and is active low (PIN_ESP32_RST in the arduino IDE).
  • GPIO24 Is connected to the mode pin of the ESP32C3. If it is pulled low at the same time the reset signal is going high the chip will enter flash mode (PIN_ESP32_MODE in the arduino IDE).

The ESP32C3 is also connected via the second SPI channel to allow very high transfer speeds between the ESP32C3 device and the RP2040.

SPI1 Pin usage:

  • GPIO14 is the serial clock (SCK)
  • GPIO12 is the serial data input (SDI)
  • GPIO15 is the serial data output (SDO)
  • GPIO13 is the ESP32C3 chip select signal (#CS)

The ESP32C3 SPI version of the AT command interpreter also uses an extra hand shake signal (HS).

  • GPIO18 is the ESP32CS hand shake signal.

Antenna options

The board is available with two different antenna options. The most common choice is to use the on board chip antenna that will give you very good coverage and ease of use. The second option is to buy the board with a U.FL connector and hook up an external antenna. This option is great if you need a little better coverage or if you really want to go overboard and hook up directional antennas and reach very long distances. The choice is yours.


DescriptionValueComment
Board Size50,80 mm x 22,86 mm x 3,20 mmUSB Connector protrudes ~1mm outside PCB
Main micro controllerRP2040 from Raspberry Pi133MHz dual core Cortex M0
SPIOne SPI channel configured
I2COne I2C channel configured
UARTOne UART channel configuredSecond UART is for the ESP32C3 chip
Analog inputs4 analog input channels
WLAN controllerESP32C3 from Espressif160MHz single core RISC-V core
BLE controllerESP32C3 from Espressif4 MByte internal flash memory
FLASH Memory8MByte 133 MHz
SRAM Memory264KByteDivided into 6 banks
USB 2.0 controllerUp to 12MBit/s full speedIntegrated USB 1.1 PHY
JST Battery connector2.0mm pitch
On board LiPo charger500mA standard charge current
Onboard NEOpixel LEDRGB LED
Technical Data