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RF430FRL152H Temperature Reading with TRF7970EVM

Vincent Sylvestre
Prodigy 10 points
Other Parts Discussed in Thread: RF430FRL152H, RF430FRL152HEVM

Hi,

I have designed a very simple circuit using the RF430FRL152H chip, as well as an antenna and a reference resistor, in order to read temperature values using the internal temperature sensor of the chip. Software wise, I am using the TI GUI interface for TRF7970EVM, as well as the development board to read the temperature values.

It appears that the software does detect my chip. However, when it comes to reading values, it always returns 3FFF (which, I think, translates to empty memory, is that right?).

Did I go for a design that's a little too minimalist by only using the antenna and reference resistor pins? Is there another connection that I should absolutely make in order for the circuit to work properly? Also, I was wondering: does the chip come already programmed for basic usage (temperature reading, for instance), or do I need to program it myself first?

Thank you,

Vincent

  • 0
    TI__Expert 7820 points

    Vincent,

    I hope that you have included the decoupling capacitors for the external power rails.  These are needed.  Please see the datasheet for the example circuit (toward the end) and the recommended values.

    If you are planning on using the internal temperature sensor, this will have to be calibrated first.  The datasheet only provides the slope property of this sensor, but the offset varies significantly from part to part.  

    I would recommend to use an external thermistor which can be very accurate and there is ROM support for this.

    If you plan to use the internal temperature sensor the reference resistor is not needed (it should be only used along with a thermistor).

    The chip already comes programmed for using the ROM code.  The RF430FRL152HEVM has extra programming to support the SensorHub boosterpack as well as the default functionality.

    The 0x3FFF value that you are getting likely means that the SD14 is being maxed out (0x3FFF is the highest result).  This would mean that it is not being configured properly.  If you want to go over the settings that you are doing we can help you further to configure and return a proper result.