2 Replies Latest reply on Oct 25, 2020 11:21 PM by KaBh_4706866

    Bluetooth Bulk Data Transfer




      I have a device with PSoC 5LP interfaced with a microSD Card and a Bluetooth module. I am using a Class10 microSD Card and Microchip RN4871 Bluetooth (BLE) module. The UART Communication baud rate between the Bluetooth module and PSoC is set to 230,400 bps.


      I am trying to send a relatively big file from this device to other devices like for instance, my phone, over Bluetooth. But on receiving, I find that a lot of data is lost.

      The file is a binary data file of around 60kBytes. I tried to replace it with a similar-sized text file and found similar results of data being missed. I have also tried to give a delay of 2ms to 10ms between every 100 bytes of data, but no improvements.


      But when I send 200bytes hardcoded data, I don't see it being lost. To view the data being received on my phone, I've been using this app - Serial Bluetooth Terminal


      Any suggestions to fix this? Let me know if you need any other information.

        • 1. Re: Bluetooth Bulk Data Transfer



          I'm familiar with the PSoC5LP but not with your Microchip BLE device. I'll try to make some guesses as best I can.


          I have looked at the Microchip link you provided.  It is the datasheet for the BLE device.



          • You are using the available UART comm on the RN4871.
          • You are NOT using the RN4871 pin P0_0 as UART_CTS.


          A few items should be noted:

          • The maximum UART data rate is 10Kbps.   Therefore the maximum Byte rate is 1KBps (10Kbps, 8N1). 

            Make sure the baud rate on the RN4871 (however that is accomplished) matches the PSoC5LP baud rate to less than +/- 4%.
            Here's the baud rate chart provided in the datasheet.

          • I recommend that you connect the RN4871 pin P0_0 output as an input to a PSoC5LP GPIO pin.  This pin on the RN4871 is UART_CTS by reset default.   It is possible that you might be blindly sending data from the PSoC5LP Tx port without flow control.   The UART_CTS pin is intended to signal from the RN4871 that its UART Rx buffer is full.  When full, stop transmitting from the host (PSoC5LP) side.

          I recommend before you make any changes to the wiring of your system, put a scope probe on the P0_0 and watch what is does when you are trying to send 200 bytes of data.




          PS:  To get more expert eyes on this post, you might want to move this discussion to the PSoC5 discussion forum.

          • 2. Re: Bluetooth Bulk Data Transfer



            Thanks for your suggestions!

            Yes, I have not been using the UART_CTS - without the flow control. I will have a look into this as you mentioned.


            Will keep you posted further.


            Thanks once again!