CC1101 + NRF24 Dual-Radio Module for M5Stack Cardputer ADV

A simple guide to wiring CC1101 (Sub-GHz) and NRF24L01+ (2.4 GHz) together on the M5Stack Cardputer ADV — one module with two radios, switchable from Bruce firmware. No DIP switches, no jumper caps, no hardware fiddling after setup.

Designed and tested by PINGEQUA — open-sourced for the Cardputer ADV community.

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What You Get

A working dual-radio expansion for the M5Stack Cardputer ADV: Sub-GHz (433 / 868 / 915 MHz, depending on your antenna) and 2.4 GHz, switchable from inside Bruce firmware.

This guide gives you the modules to buy, the wiring to follow, and the configuration file to drop onto your Cardputer ADV. About an hour of work if you're comfortable with basic soldering or jumper wires.

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Parts List

Two off-the-shelf modules:

Module	Part Number	Notes
NRF24L01+	AS01-ML01DP5	High-power version with built-in PA + LNA
CC1101	AS07-M1101D-SMA	Has a built-in SMA antenna connector

Plus:

• 1× 3.3V LDO regulator (AMS1117-3.3 or similar, 300 mA+)
• Hookup wire or Dupont jumpers
• 2× SMA antennas (one for your Sub-GHz band, one for 2.4 GHz)

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Wiring

Shared SPI bus (one bus, both modules):

Signal	GPIO
SCK	GPIO 40
MOSI	GPIO 14
MISO	GPIO 39

CC1101 (Sub-GHz):

Signal	GPIO
CSN	GPIO 13
GDO0	GPIO 5
GDO2	not connected

NRF24 (2.4 GHz):

Signal	GPIO
CSN	GPIO 6
CE	GPIO 4
IRQ	not connected

Power:

Signal	Source
5V in (from Cardputer ADV)	EXT Pin 6
3.3V out (to both modules)	via LDO
GND	EXT Pin 4

See docs/pin-mapping.md for the full Cardputer ADV header reference.

Before powering on: check with a multimeter that the two CSN lines (CC1101 GPIO 13 and NRF24 GPIO 6) are not shorted together. The SPI lines (SCK / MOSI / MISO) should be continuous across both modules.

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Configuration

Bruce keeps pin assignments in /brucePins.conf. It is a JSON file, and its top-level key is your device's Wi-Fi STA MAC address in uppercase colon-separated form. Edit the CC1101_Pins and NRF24_Pins sections:

{
  "A1:B2:C3:D4:E5:F6": {
    "CC1101_Pins": { "sck": 40, "miso": 39, "mosi": 14, "cs": 13, "io0": 5, "io2": -1 },
    "NRF24_Pins":  { "sck": 40, "miso": 39, "mosi": 14, "cs": 6,  "io0": 4, "io2": -1 }
  }
}

Replace A1:B2:C3:D4:E5:F6 with your own device's MAC — Bruce ignores any block whose key doesn't match. If the file already exists, your MAC is already the top-level key; just edit the values underneath it.

The sck / miso / mosi values above are Bruce's defaults for the Cardputer family, so in practice only cs and io0 need changing. io0 carries a different signal per chip: GDO0 for CC1101, CE for NRF24. io2 is unused in this design.

Which copy to edit: the file lives in the device's internal LittleFS and, if you use one, on the SD card. Bruce reads whichever storage is active — SD card if one is mounted, LittleFS otherwise. So edit the copy on the storage you actually boot with; if you normally run with an SD card inserted, that is the SD copy. Restart after editing.

To access the WebUI for editing: on the Cardputer go to Files → WebUI, connect to your Wi-Fi, then open the IP address shown on screen in a browser. Default login: admin / bruce.

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Verify It Works

After restart:

1. CC1101 check: Bruce → RF → Config → set RF Module to CC1101, set your frequency (433.92 / 868.30 / 915.00 MHz), open the Spectrum Analyzer. You should see RF noise plus spikes from nearby remotes.
2. NRF24 check: Open any NRF24 tool (e.g. NRF Spectrum), select SPI Mode. You should see 2.4 GHz channel activity (Wi-Fi makes a good reference).
3. Switch test: Open CC1101, exit, open NRF24. The transition should be instant — no reset needed. That's the auto-switching working.

If anything doesn't work, see docs/troubleshooting.md.

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Notes

• This works only on the Cardputer ADV (Stamp S3A version). The original Cardputer v1.0 / v1.1 has a different expansion slot and will not work.
• Bruce firmware is not pre-installed — flash it yourself from github.com/BruceDevices/firmware.
• Why reassigning pins is necessary: Bruce's stock Cardputer build points both radios at the same pins — CC1101_SS_PIN and NRF24_SS_PIN both resolve to GPIO 1, and CC1101_GDO0_PIN and NRF24_CE_PIN both to GPIO 2 (see boards/m5stack-cardputer/m5stack-cardputer.ini). That is fine with a single module attached, but it makes the two impossible to run side by side. Giving each chip its own CS is what lets both stay wired at once.
• Sharing one SPI bus between them is handled by Bruce itself: acquireSharedSPI() in src/core/bus_HAL.cpp only tears down and re-inits the bus when the SCK/MISO/MOSI trio actually changes. Since both radios here sit on the same three pins, switching between them costs nothing and needs no reboot.

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Also Available

Don't want to build from scratch? The same design is also available as a ready-made module — the Hydra RF series by PINGEQUA, in 433 / 868 / 915 MHz variants. Search "Hydra RF" or visit pingequa.com if you're interested.

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License

Documentation under MIT License. Hardware diagrams under CC BY-SA 4.0.

PRs and issues welcome — especially build photos, alternative module combinations, and translations.