Challenger RP2040 SubGHz (915MHz)

The Challenger RP2040 SubGHz board is an Arduino/Circuitpython compatible Adafruit Feather format micro controller board based on the Raspberry Pico (RP2040) chip.

This is a spin-off from our Challenger RP2040 LoRa board but in this case we replaced the LoRa module with a low power SubGHz radio module also from Hope RF. The transceiver features a proprietary long range modem that provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption.

SubGHz radio

The RFM69HCW is a transceiver module capable of operation over a wide frequency range, including the 315,433,868 and 915MHz license-free ISM (Industry Scientific and Medical) frequency bands. Currently we are only supporting the 868 and 915MHz bands but this may change in the future. All major RF communication parameters are programmable and most of them can be dynamically set. The RFM69HCW offers the unique advantage of programmable narrow-band and wide- band communication modes.

The RFM69HCW is connected to the RP2040 via SPI channel 1 and a few GPIO’s that is required for signaling. A U.FL connector is used to attach your antenna to the board.

• +20 dBm – 100 mW Power Output Capability
• High Sensitivity: down to -120 dBm at 1.2 kbps
• High Selectivity: 16-tap FIR Channel Filter
• Bullet-proof front end: IIP3 = -18 dBm, IIP2 = +35 dBm,80 dB Blocking Immunity
• Low current: Rx = 16 mA, 100nA register retention
• Programmable Pout: -18 to +20 dBm in 1dB steps
• Constant RF performance over voltage range of module
• FSK Bit rates up to 300 kb/s
• Fully integrated synthesizer with a resolution of 61 Hz
• FSK, GFSK, MSK, GMSK and OOK modulations
• Built-in Bit Synchronizer performing Clock Recovery
• Incoming Sync Word Recognition
• 115 dB+ Dynamic Range RSSI
• Automatic RF Sense with ultra-fast AFC
• Packet engine with CRC-16, AES-128, 66-byte FIFO
• Built-in temperature sensor

We support both 868MHz and 915MHz systems by using the specific sub GHz module (RFM69HCW-868S2, RFM69HCW-915S2) as required for each region.

Pinout

LiPo battery / charger

The board is equipped with a standard 2.0mm JST connector for connecting a rechargeable LiPo battery. There is also an internal battery charger circuit that charges your battery as long as a USB cable is inserted or the VUSB connection is connected to 5V.

USB Type C

In the recent years we have noticed that we are seeing more and more USB Type C cable laying around the lab due to the fact that all new phones and accessories use them. As of yet we haven’t seen any shortage of micro USB cables but we are not getting any new ones any more and old ones do break occasionally. So we decided to go for a USB Type C connector for this board. A bonus of this is that they are quite bit more durable and you don’t have to fiddle with the cable before plugging it in.