January 19 2023


Ultimate CNC tried to use bluetooth using the BLE and SPP protocols. The BLE protocol could work, but we finally removed it. In our test, using the protocol with BLE chipset CC2640R2F works, but not well enough to actually work.

This chipset CC2640R2F handle 256B RX and arduino 128B RX, so if you send a "G-code package" less of 128B, it works. Problems:

  • Signal Stability.
  • Complexity to handle it.

So, using the SPP protocol works well.

You can try use bluetooth SPP connection when:

  • You are concerned about high currents on your board and pc and prefer physical separation between them. For example, the "small" Nema 23, can manage about 3A.
  • You are experiencing suddenly disconnects, and you don't find the reason. Maybe EMI issues ?. To fix it, sometimes is impossible. In this case, try with Bluetooth protocol SPP, it is transparent for your board.
  • If your scenario is something like this: 3 stepper motor in your board (Nema 23+), USB connection at 115200bps, and micro-steps (PWM),... you probably, need bluetooth connection. Nema17 is a complete scenario different, some users haven't problems.


If you want to use Bluetooth connection with Ultimate CNC, the module JDY-31 are working.

  • Bluetooth 3.0 SPP.
  • Tested at 115000 bps. Other bps are not tested, but should be work.
  • Windows 10.

A lot of hardware are tested for this task, but finally, JDY-31 have worked well for long time.

Configure JDY-31

Check on folder: devices/jdy31.ino (needs Arduino IDE). This file will configure your own device.