SC14CVMDECT Devboard

There is an Open Hardware Devboard for the SC14CVMDECT module by Renesas/Dialog Semiconductor.

The sources/design files of the board can be found here.

The board offers a simple breakout of the pins of the SC14CVMDECT module. It can be powered via USB-C and the UART interface of the module is exposed on USB.

It has a hardware reset button for the DECT module. Additionally the reset pin of the module can be optionally connected to an GPIO pin of the UART converter chip via a jumper to be able to reset the DECT module via software.

It has two LEDs connected to the LED3/LED4 pins of the module. When working correctly D2 (the LED connected to pin LED3) blinks shortly when the board is powered on. If there is an issue with the DECT module it stays on.

The module uses a variant of HDLC as the base protocol for its binary UART interface. It works by sending and receiving frames. The flag/frame delimiter used is 0x10. The structure of a frame looks like this:

1 Byte Flag 0x10 | 2 Byte Frame Size | 1 Byte Control Code | N Byte Payload | 1 Byte Checksum

An existing parser implementation for the frames can be found here.

When powered on the module starts sending out frames with a control code of 0xC8 and a payload length of 0. To sync with the module you have to mirror this frame back. Afterwards more frames are received from the module.