Part Number: CC430F5137
Other Parts Discussed in Thread: CC1101
We are a data company based out of the UK who use a data collection device which utilises RF transmission. The device is an instrumented mouthguard which transmits data using an ST Electronics low powered transceiver component. During use, this RF transmission is captured by a receiver plugged into a PC nearby.
This set up is certified for FCC and CE, with the caveat that during compliance testing, the frequency band had to be made wider for the FCC regulations:
|
|
CE |
FCC |
|
Base Frequency |
868 MHz |
921 MHz |
|
Frequency Deviation |
20 kHz |
229 kHz |
|
Channel Bandwidth |
100 kHz |
541 kHz |
In the past we have used an ST chip on the RX side, however, we have now switched to using the CC430F5137 by Texas Instruments.
Using our CE settings, the transition has been seamless, and the performance is almost identical to what was achieved with the ST chip. However, in the US where we use the FCC settings, the range at which the product can work has decreased massively. The table below displays this.
|
|
CE |
FCC |
|
ST CHIP |
100m range |
100m range |
|
TI CHIP |
100m range |
5m range |
From the documentation, we can’t work out if we are setting a register wrong or maybe missing something additional that needs to be set.
Currently they are set through:
WriteSingleReg(MDMCFG4, FCC_15_247_MDMCFG4_38400);
WriteSingleReg(DEVIATN, FCC_15_247_DEVIATN);
WriteSingleReg(FSCTRL1, FCC_15_247_FSCTRL1);
WriteSingleReg(FSCTRL0, FCC_15_247_FSCTRL0);
WriteSingleReg(MDMCFG3, CCDEF_MDMCFG3);
WriteSingleReg(MDMCFG2, CCDEF_MDMCFG2);
WriteSingleReg(MDMCFG1, CCDEF_MDMCFG1);
WriteSingleReg(MDMCFG0, CCDEF_MDMCFG0);
With definitions:
#define FCC_MDMCFG4_38400 0x2A // Modem configuration. Rx bandwidth = 542kHz, Speed = 38 Kbps
#define CCDEF_MDMCFG3 0x83 // Modem configuration.
#define CCDEF_MDMCFG2 0x13 // Modem configuration. FSK/GFSK
#define CCDEF_MDMCFG1 0x22 // Modem configuration.
#define CCDEF_MDMCFG0 0xF8 // Modem configuration.
#define FCC_DEVIATN 0x71 // Modem deviation setting (when FSK modulation is enabled). 0x72: -6dB BW = 554kHz
#define FCC_FSCTRL1 0x0c // Frequency synthesizer control.
#define FCC_FSCTRL0 0x00 // Frequency synthesizer control.
From this information, is there any reason you can see for the decrease in performance since switching from the ST chip to the TI chip?
