First radio waves

First prototypes of our Radio Board v1 have been implemented succesfully. The board is based on TI’s CC430 technology platform. The exact model of the chip is CC430F5137 with 32K of flash and 4k of RAM, although these prototypes are using samples with only 8K of flash.

The CC430 combines an MSP430 MCU and a CC1101 sub-1-GHz radio module.

The MSP430 is a cheap ultra-low power 16-bit microcontroller platform. You can get a LaunchPad development board with two MSPs and a USB cable for 4.30$. There was a one euro difference in the price of the CC430 and the plain CC1101 radio in Digikey so we didn’t really consider using the plain CC1101 directly with STM32 but went for CC430 where we can have the SW stack for radio running in a dedicated MSP430.

The CC1101 can use frequencies like 868 MHz (Europe) and 915 MHz (USA) but we are using 433 MHz (Worldwide) for better structure penetration. Internally the CC430 is using a cpu interface with memory mapped registers for communication between the MCU and radio core. The CC1101 is quite convenient to the application developer as it can send and receive CRC checked variable length messages sent to specified address.

 

Home-made Radio Board v1 prototype

First Radio Board v1 prototype

 

Our initial plan was to use Dash7 as the radio SW stack but it doesn’t fit to 8K and seems to be quite an overkill for our initial use cases. TI provides a free but proprietary stack called SimpliciTI but the license seems to restrict redistributing the source code (although I’m no lawyer) and we prefer open source solutions anyway. Luckily TI provides a nice set of RF examples for the CC430 and since the CC1101 provides a high level packet handling API, one can get quite far by using only this API.

The MSP430 is well supported in Linux and e.g. Ubuntu provides msp430-gcc and msp430-gdb. The CC430 RF examples do contain a couple of lines specific to TI’s proprietary Code Composer Studio IDE but they can be relatively easily ported to GCC. Connect the LaunchPad via USB to your Linux box and your CC430’s TEST and RST to the launchpad and you are ready to go. More about the exact instructions later.

 

CC430 prototyping

Mimicing TI's CC430 evaluation board with leds and a button

 

Currently we are implementing the CC430 firmware for better interoperability with the Control Board and finalizing the Radio Board v1 gerbers for PCB order from ITead Studio.

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