Open hardware LPC1343 board with RFM22B transceiver and USB interface

Here I present a design of a board with LPC1343 connected via USB to host PC, which can communicate via SPI to the RFM22B transceiver module. The main aim was to check whether RFM22B can be used as a replacement of simpler TX and RX OOK 433MHz modules by Aurel. Using the direct mode of the Si4032 transceiver chip and (de)coding the packets within the LPC1343 MCU I was able to both transmit and receive Keeloq-compatible data packets.

The schematics is usb_lpc_rfm.pdf and the open hardware Kicad design files are usb_lpc_rfm.zip .

Although I have written my own code in the end, it was useful to read a a discussion at this forum (in german). Note that the register descriptions of Si4032 are incomplete in any single manual and I had to combine the datasheet of Si4032, the RFM22B manual, and the SI4430's AN440 application note to get all required information.

Presently there is a program rfm22direct.c and lib/rfm22.c in the tar file arm_lpc111x.tar.gz It implements the direct mode OOK/FSK setup, and uses 16 bit timer0 and timer1 from LPC1343 to (de)code the Keeloq-compatible packets, using actually the same code which I used previously with the simple Aurel OOK modules. The user communicates with the LPC MCU via USB virtual serial port (/dev/ttyACMx on linux), as has been described elsewhere . My contributions are under the GPLv3 license, some other parts may be under other licenses, cf. individual files. Support for the native packet communication provided by Si4032 is not coded presently, but that should be quite straightforward and one can also use for this purpose the RadioHead library.

Open hardware LPC1115 board with RFM22B transceiver and ethernet interface

I have also designed a board with LPC1115, which interfaces the RFM22B transceiver to ethernet. The aim is to provide an extensible and hardware-independent remote-control interface to an alarm central based on Raspberry Pi or similar IOT Linux machine. The design schematics is eth_lpc_rfm.pdf and the open hardware Kicad design files are eth_lpc_rfm.zip . Corresponding open source software is eth_rfm_interface.c in the tar file arm_lpc111x.tar.gz.
I have got the PCB from China after a large delay due to the Covid-19 epidemy, but finally it arrived and after soldering it and a little debugging of the software everything worked fine. The device will be used to translate the wireless messages from new remote controls at FSK 868MHz to UDP packets, which in turn will be processed by the existing alarm+door opener device, which required only software modification. The 434MHz band I used so far became so full of interference, that the range and reliability of the previous simple OOK remote controls were not acceptable any more.











I have decided to design my own matching remote controls at 868MHz FSK with Keeloq-compatible floating code encryption using the RFM119 module/CMT2119A chip.



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