NRF52840 Promicro Module

NRF52840 ARM Cortex-M4F Promicro Module

Bluetooth 5 Thread Zigbee ANT 2.4 GHz Wireless Communication Transceiver 64 MHz 1 MB Flash 256 KB RAM AES SHA-256 TRNG

     NRF52840 Promicro Module is a small development board that offers the Nordic nRF52840 wireless microcontroller in the Pro Micro size and pinout. A 64MHz ARM Cortex-M4F processor, 1MB Flash and 256KB RAM share the chip with the radio; Bluetooth 5 (BLE), Bluetooth Mesh, Zigbee, Thread (IEEE 802.15.4), ANT and 2.4GHz proprietary protocols are used without an extra module. The antenna is on the board. The board measures about 33mm x 17.8mm.

     The board is designed to be compatible with the nice!nano v2 and comes with the Adafruit UF2 bootloader from the factory: when the RST pin is touched to GND twice quickly, it appears on the computer as a USB drive and software is loaded by copying a .uf2 file to this drive. The USB Type-C socket is used both for programming and for charging a 3.7V lithium battery connected to the B+ / B- pads; the onboard charger charges the battery at about 100mA.

     Thanks to battery charging and the Pro Micro footprint it suits making Pro Micro socket mechanical keyboards wireless (with the nice_nano_v2 board target in ZMK), battery powered sensor nodes and Bluetooth remotes. Each side has the 12 Pro Micro pins plus the B+ / B- battery pads at the USB end, and there are 3 extra pins in the middle of the board (2.54mm pitch); the pin headers come unsoldered.

Key features:

     Multi protocol radio: The nRF52840 radio supports Bluetooth 5 (BLE, 2Mbps), Bluetooth Mesh, Zigbee, Thread and ANT; it has +8dBm transmit power and -95dBm receiver sensitivity.

     Battery charger: A 3.7V lithium battery connects to the B+ / B- pads; while USB Type-C is plugged in the battery is charged on board at about 100mA, and when USB is removed the board runs from the battery.

     Pro Micro and nice!nano compatibility: The pinout and size are the same as the Pro Micro; it fits keyboards and boards with a Pro Micro socket, and software and board definitions written for the nice!nano v2 are used.

     UF2 loading without a programmer: Thanks to the Adafruit UF2 bootloader no separate programmer is needed; a file is loaded like copying to a USB stick.

     Security blocks: ARM CryptoCell, 128 bit AES CCM encryption, SHA-256 and a true random number generator (TRNG) are in hardware on the chip.

Features:

• Product type:    nRF52840 Bluetooth 5 development board, Pro Micro size, nice!nano v2 compatible
• Model: NRF52840 Promicro Module
• Chip: Nordic nRF52840
• Processor: ARM Cortex-M4F (with FPU), 64MHz
• Memory: 1MB Flash, 256KB RAM
• Wireless protocols: Bluetooth 5 (BLE), Bluetooth Mesh, Zigbee, Thread (IEEE 802.15.4), ANT, Nordic 2.4GHz proprietary protocols
• Radio data rate: up to 2Mbps (BLE)
• Transmit output power: +8dBm
• Receiver sensitivity: -95dBm
• Antenna: ceramic antenna on board
• NFC: NFC-A tag (Type 2) support (external NFC antenna required)
• Interfaces: UART, SPI, I2C (TWI), PWM, PDM, I2S, QSPI (32MHz), USB
• ADC: 12 bit, 200ksps
• Security: ARM CryptoCell, 128 bit AES CCM, SHA-256, TRNG
• Pins: 21 GPIO (18 on the edges, 3 extra in the middle), 2.54mm pitch; RAW, VCC, RST, GND, B+, B-
• USB socket: Type-C (programming and battery charging)
• Power supply: USB Type-C 5V or 3.7V lithium battery on the B+ / B- pads
• Chip supply range (nRF52840): 1.7V - 5.5V
• VCC pin: 3.3V output (to power external sensors)
• Battery charging: onboard lithium battery charger, about 100mA
• Status LED: P0.15
• Bootloader: Adafruit UF2 (nice!nano v2 compatible); entered by touching RST to GND twice
• Software support: ZMK (nice_nano_v2), Zephyr / nRF Connect SDK (promicro_nrf52840), CircuitPython, nRF5 SDK, Arduino (nRFMicro-Arduino-Core)
• Colour: Black PCB
• Dimensions: about 33mm x 17.8mm
• Weight: about 5gr

Usage information:

• To load software, connect the board to the computer with a USB Type-C data cable and touch the RST pin to GND twice within 0.5 seconds. The board appears on the computer as a USB drive; copy the compiled .uf2 file to this drive and the board restarts with the new software when copying ends.
• For a wireless keyboard select nice_nano_v2 as the board in ZMK; in Zephyr the board target is promicro_nrf52840. For Arduino IDE use the nRFMicro-Arduino-Core board package, for CircuitPython use the SuperMini nRF52840 build.
• If a battery is used, solder the positive of the 3.7V lithium battery to B+ and the negative to B-. While USB is plugged in the battery charges; when USB is removed the board runs from the battery.
• Pin numbers are in port.pin form: "006" on the board means P0.06, "104" means P1.04. Define the pins with these names in software.

Applications:

•  Wireless mechanical keyboard (keyboards with a Pro Micro socket)
•  Ergonomic keyboards: building two piece (split) keyboards
•  Remote and macro keypad (Bluetooth, presentation remote)
•  Sensor nodes: battery powered temperature, humidity and door sensors
•  Smart home devices with Zigbee and Thread
•  Wearable devices and tracking tags
•  Bluetooth Mesh networks and lighting control
•  BLE devices talking to a phone (data logging, measurement)
•  Bluetooth mouse and game controller
•  Wireless software development with nRF52840 and Zephyr
   

Precautions:

•  Connect only a single cell 3.7V lithium battery to the B+ / B- pads; a reversed battery damages the board. A battery with its own protection circuit is recommended.
•  GPIO pins are 3.3V logic; a 5V signal must not be connected directly.
•  This board is a nice!nano v2 compatible board; it uses the Pro Micro pinout but it is not an ATmega32U4. AVR (ATmega32U4) software written for the Pro Micro does not run; software compiled for the nRF52840 is needed.
•  The antenna is on the board; metal parts, a battery or wires above or below the board reduce the wireless range.
•  If battery life matters, switch off unused LEDs and the VCC output in software; LEDs that stay on increase the standby current.

Package contents:

•  1 Piece NRF52840 Promicro Module
•  2 Pieces 12 pin male header (unsoldered)
•  1 Piece 3 pin male header (unsoldered)
•  Note: Lithium battery and USB Type-C cable are not included in the package.

Software support:

•  nRF5 SDK: nordicsemi.com/Products/Development-software/nRF5-SDK
•  nRF Connect SDK: github.com/nrfconnect/sdk-nrf
•  Zephyr board page: docs.zephyrproject.org/latest/boards/others/promicro_nrf52840/doc/index.html
•  Arduino core (nRFMicro, SuperMini nRF52840, nice!nano v2): github.com/pdcook/nRFMicro-Arduino-Core