user129301

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• Espruino MDBT42Q Breakout for 1kHz Signal Acquisition

  @user129301 started

  • 8 comments
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  @Gordon replied
• Espruino MDBT42Q Breakout for 1kHz Signal Acquisition

  in General • 2 years, 10 months

  

  Thank you very much for your reply. My first plan is to communicate the data with the PC from the Espruino. I have ordered the MDBT42Q and keep you posted of my progress. I am still a novice using this device so please don't mind me asking a lot of question in the future.

  Thank you again.

  ZJ

• Espruino MDBT42Q Breakout for 1kHz Signal Acquisition

  in General • 2 years, 10 months

  

  Thank you very much for your reply.

  I should have mentioned the Master side in my previous message. Yes, at this point I intend to use an MDBT42Q at the Master side too and in order to check the result of the transmission, I wanted to print the result.

  I would be grateful for your feedback on the Master side (RX) pseudocode as well.

  I am grateful for your event based transmission comment in your previous message, and the code seems simple enough to modify and test.

  Additional question: Is the process of receiving and handling data different when using a phone/PC.

  I would be grateful for your response.

  ZJ

• Espruino MDBT42Q Breakout for 1kHz Signal Acquisition

  in General • 2 years, 10 months

  

  Thank you very much for your reply and it certainly helps!

  We are of course designing our own board which is why the dimensions are important.

  I am still getting around Bluetooth 5.0 and Java (I am more used to C). I found out that BLE 5.0 is capable of sending a max. of 244 bytes in a packet. I had been pondering on a pseudocode for a fast transmission of a 500 Hz biosignal. Suppose we receive the data from an ADC in INT or UNSIGNED INT format. In that case, I want to send 200 bytes (containing 100 sample values). These 100 values are sampled at 1 ms. These 100 samples (which would take roughly 0.1 s to record) would be placed in a TX buffer and would be sent to the Master device. I would be grateful if you could check my (rough and simple) pseudocodes below to see if my concepts are right.

  TX (Peripheral Side)

  START:
  Global Variable Buffer;

  setup()
  {
  BLE initialization // (incl. Peripheral setting, advertising)
  Establish connection with Master
  }

  Loop()
  {
  Buffer = Samples of ADC values using Waveform Class @ 1 kHz
  Transmit Buffer to Master // transmitting 200 bytes (100 samples) in 0.1 sec
  }

  END:

  RX (Master Side)

  START:

  Global Var flag; // flag for receiving new values in buffer
  Global Var Samples_ADC; //contains 100 received ADC values
  Global Var count = 0; // counter for Samples_ADC

  setup()
  {
  Initialize Serial
  Initialize Timer Interrupt
  BLE initialization // (incl. Master setting, Receive advertisements)
  Establish connection with Master // (Including min. and max. connection interval setting)

  }

  Loop1()
  {

  Buffer = Receive Values
  Samples_ADC = Parsed Buffer values // Contains transmitted values and parse

  Flag = 0;
  Timer Interrupt en = 1;
  while(Flag == 0); // wait until Flag is 1
  }

  Timer Interrupt ISR (called after 1 ms)
  {
  if (count == size(Samples_ADC)) --> count = 0, Flag = 1; //reinitialize count and flag
  Print(buffer(count)); // prints each value in buffer after 1 ms
  count++;

  }
  END:

  I have written down this rough C based pseudocode off the top of my head. I request you to kindly critique on it and comment if I have to worry about timing issues i.e data back log or loss etc.

  Please understand my lack of knowledge of BLE. I would be grateful for any replies.

  Thank you
  ZJ

• Espruino MDBT42Q Breakout for 1kHz Signal Acquisition

  in General • 2 years, 10 months

  

  Dear Administrator,

  I hope that you are in good health.

  I am working on an application for transmitting a 500 Hz biosignal from an external signal acquisition device wirelessly to a computer or another remote device. For this design, I require a board with an in-built ADC along with a wireless transceiver (preferably Bluetooth for stable connection). While searching the internet, I stumbled upon the Espruino MDBT42Q module.

  I have some experience with Bluetooth 4.0 Low Energy using Red Bear Nano modules; however, as far as I remember, they could only provide 125 Hz using the Arduino IDE.

  My main requirements are as follows:

  1) Sample transmission and receive at at least 2 kHz to overcome the signal of 500 Hz at its highest frequency.
  2) A module compact in size which can be fitted in a rectangular space of 18 mm x 30 mm.
  3) Must have an ADC module to input analogue signals.

  To the best of my understanding, I found Espruino MDBT42Q which uses the Nordic Semiconductor nRF52832 the most appropriate to my application. I would be grateful if you can let me know if my understanding is correct. I would also be grateful if you could provide me with other options with improved features i.e. smaller size, higher resolution ADC, faster transmit/receive.

  I have an additional question regarding programming the Espruino MDBT420 board. I was reading the "Getting Started" page and I found out that the device can programmed wirelessly using a Web IDE provided we have a compatible in built Bluetooth module and Web Bluetooth. Have I understood that correctly?

  I would be grateful for any replies.

  Thank you.

  ZJ