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CCS/RF430FRL152H: using ADC pin of another MCU connected with NFC chip input port.

Part Number: RF430FRL152H
Other Parts Discussed in Thread: RF430CL330H, MSP-EXP430G2ET, MSP-EXP430F5529LP, DLP-7970ABP, TRF7970A

Tool/software: Code Composer Studio

Dear all,

hello my name is minhyung.

I am using RF430FRL152H and MPS-EXP430G2ET + DLP7970ABP to create a customboard.

The RF430FRL152h custom board which operates with NFC is to receive the LED light by the light sensor and send the data to the master kit MPS-EXP430G2ET + DLP7970ABP and send it to the PC to display it. We were going to display the data in Matlab.

I succeeded in plotting graphs in real time by receiving raw data with matlab. However I have additional problem. I want the sampling rate of 25Hz.

But I get to know it is impossible at SD14 ADC of RF430FRL152H.

So I think it can be resolved if another MCU is added. If the light sensor is connected to another MCU that have faster sampling rate and the MCU transfer the ADC data to the NFC chip, NFC chip transmit the data to PC and the data can be get in matlab. Is it possible? If it is possible, I have to know command that display the Digital input data of port as shown in the picture below. Can you inform the command?

I am using the NFC chip not programmed. So, in order to use Digital input port, I think i have to program the NFC chip. Right? Or can I try the above mentioned method with the NFC chip with the default code?
please reply...TT

  • Hello Minhyung,

    That is possible, but you'd not want to use the RF430FRL152H at that point. I'd recommend using something like the RF430CL330H. If you aren't able to leverage the SD14 functionality of the RF430FRL152H, it is neither cost efficient nor simple to use. The RF430CL330H would be a very easy to use device with a simple I2C interface that can be controlled by a host MCU and still perform NFC functions.

    All you'd need to do with that device is to turn the data from the light sensor into a message sent to the RF430CL330H over I2C, and then enable it's RF functionality so the data can be read.

    As far as the commands you are referring to, they wouldn't exist in the examples we have provided as the use case you have outlined is not the intended use case for the RF430FRL152H and therefore we do not have any examples to offer along those lines.
  • Thanks to your reply.
    I understand your suggestion. But I want to use RF430FRL152H. I will give you some reason. First, I already have designed and made circuit in bread board. Second, I want to use SD14 ADC of RF430FRL152H for thermal senor. Measurement of temperature dosen't need fast sampling speed. So I want to make custom board by using RF430FRL152H. Is there anything I can refer to to find the command to receive the port input response?

    Also, In 'Frequently Asked Question for RF430FRL15xH Devices', 

     I think the shorter conversion time is more important for me than accuracy. How do I get fast conversion times instead of accuracy?

    Finally, If I use the RF430CL330H, it can communicate with MSP-EXP430G2ET+DLP7970ABP ? 

  • Hello Minhyung,

    There is a difference between the rate at which you can sample and the sample conversion time, so in return to your question I have one of my own: Where is the requirement for 25 Hz sample rate coming from? Does the sensor need to be sampled at that rate, or can it be sampled at 1 Hz? If it can be sampled at 1 Hz, that may be possible then because the requirement is the bandwidth is 1 Hz. The conversation times can range from 16 ms to 1 second.

    Yes the RF430CL330H can communicate with the MSP-EXP430G2ET and DLP-7970ABP, though even more optimal would be to use the MSP-EXP430F5529LP with the DLP-7970ABP which has better support for NDEF which is how the RF430CL330H formats packets.
  • Hello Ralph Jacobi,

    The reason why I need to set the sample rate to 25 Hz, ie, the sample speed is 40 ms, is because the paper I'm following has done so. The paper deals with pulse oximeter capable of NFC communication. In order to measure heart rate and oxygen saturation, the red LED and the IR LED are alternately turned on at intervals of 83 ms, and the photo detector samples data by sampling every 40 ms. Although the NFC chip used in the paper is not RF430FRL152H, I bought RF430FRL152H because the NFC chip (SL14A) used in the paper was discontinued. In my custom board, the speed of displaying the data by using matlab is about 0.5s. Currently, research based on the RF430FRL152H NFC chip has progressed considerably and it was time consuming, so if possible, I would like to proceed without changing the chip. But I am really grateful for your suggestion to change the NFC chip . Thanks to your kindly reply.

    There are a few more questions.
    1. My current MCU (Attiny10) is equipped with 8bit ADC. Could this be a problem in getting the digital data of the sensor converted from MCU with RF430FRL152H or RF430CL330H?

    2. You said max sampling rate was 1Hz, but in my case it is about 2Hz. I want to know the reason.

    3. RF430FRL152H, NFC chip (SL14A) used in the paper is ISO156693. However, RF430CL330H is ISO14443B. Could this be a problem?

    4. Can we just use the RF430CL330H NFC BoosterPack to make the test circuit? Is it possible to use it without programming separately?

    Currently I am experimenting with a test circuit on a breadboard. And the design of the PCB circuit which I commissioned to manufacture is as follows. You can ignore some Korean words. This is irrelevant to the question.

  • Hello Minhyung,

    If it's just for research purposes and you aren't going into mass production with this application, you could use the RF430FRL152H over the RF430CL330H as an NFC interface. It's not cost efficient but that wouldn't matter in your case.

    You'd have to send data to it with a host MCU though, and we don't have code available with the RF430FRL152H being used a slave device as that is not a use case that comes up with customers. So you'd have to develop that on your own.

    Again when I say max sample rate is 1 Hz, it means that the maximum bandwidth of the input signal that can be reliably sampled, if you sample anything faster than 1 Hz, you will not be able to get reliable and accurate readings.

    Ultimately it's up to you to decide which path makes the most sense:

    1. Develop slave code for the RF430FRL152H and use it as an NFC interface, and read the ADC with the proper rates from your MCU and load that data to the RF430FRL152H to transmit over ISO15693
    2. Use the RF430CL330H instead as the NFC interface using ISO14443B
      1. You can look at these TI designs for reference of sensor applications with the RF430CL330H, and you can use the BoosterPack for initial evaluation

    I am not sure of your reader device, but in principal there should be no difference unless your reader is protocol limited to ISO15693 only which is rare now. If you want to communicate with smartphones, the RF430CL330H is actually better for this anyways as the RF430FRL152H default message structure is not NDEF compliant (what smartphones use) so you'd have to do a bit of special handling to get the message NDEF formatted.

  • Hello Ralph Jacobi,

    Thanks to your kindly reply. I fully understand your reply and agree that using RF430CL330H is a better choice.

    However, I have more question about RF430FRL152H.

    I searched several papers related to the NFC chip and could find the papers that the author used RF430FRL152H and TRF7970A for research. This is a paper titled "Modular and Reconfigurable Wireless E-Tattoos for Personalized Sensing" in the journal Advanced material technology. In this paper, the authors sampled ADC data with RF430FRL152H and TRF7970EVM and set the sampling rate up to 25Hz. Why was the sampling rate of 25 Hz possible in this paper? In this paper, did the author choose a fast sampling rate instead of a high accuracy? Is this possible? I am curious about your opinion of this. I attached some excerpts from the paper. If you want to see the whole paper, please contact me on my personal e-mail and I will send you a paper.

    I am always thankful for your help.

  • Hello Minhyung,

    I am not sure how they got reliable results with that. That violates D/S specs. Maybe they had a manner to get a reliable reading, or maybe the devices they used performed better on ADC. For limited modules on research that is completely reasonable because the specifications are our guarantee across all devices, but some devices can perform better than others (if familiar with GPU's in PC's, it's no different than binning).

    All that said, at the end of the day as a TI engineer, I must stand by our datasheet specifications and advice it not be used outside of specifications.

  • Hello Ralph Jacobi,

    Thanks to your kindly reply. 

    I have one more question... I'm sorry to bother you.

    1. can I receive the digital data converted by ADC of MCU by the digital sensor of RF430FRL152H after programming the sensorhub code on the RF430FRL152H? sensorhub command
    Here is the code that gets the value of the digital sensor in this thread. From the table below, I can see that Port 1.4 ~ 1.7 acts as a digital sensor.

    2. Currently, I am using only ADC0 of RF430FRL152H. Can we speed up the sampling rate by disabling ADC1 and ADC2?

  • Hello Minhyung,

    1) That would treat the RF430FRL152H as the host device, which in theory you could do, but it would be a bit difficult from a protocol standpoint because you'd have to request the MCU to send you data with a device that has limited code instead of letting the more powerful MCU just tell the RF430FRL152H when it has data and send it over. Probably possible to do, but I would not recommend it.

    2) No, the sample speed limitations are hardware limitations due to the design of the SAR ADC in the device.

  • Thank you so much.^^