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MSP432P401R: UART data loss

Jayden Hewer
Prodigy 20 points

Part Number: MSP432P401R

Hello

My project is a bidirectional SPP<->UART gateway for high-speed communication between a phone or computer and a third-party device. Our Bluetooth module consists of a MSP432P401R and a CC2564.

We are seeing intermittent data loss and are trying to find the cause.

We are using 3 UARTs:

  1. Host UART
    1. Baud rate 921600
    2. Hardware flow control implemented in software
    3. DMA on the receive path
  2. Debug UART
    1. Baud rate 115200
  3. HCI UART
    1. Using stack code
    2. Baud rate 2000000 (defined by the stack)
    3. High IRQ priority
    4. Hardware flow control

In SPPAPI.h I saw the following comment “The following Constants represent the ONLY allowable Baud Rates (Bits/Second) that are supported by the Serial Port Profile.” With the highest supported baud rate being “SPP_BAUD_RATE_230400”. For this reason, I reduced the HCI UART from 2000000 to 230400, however this caused receive errors (0x24) on the host UART. My preliminary investigation showed that reducing the baud rate on the HCI UART had a negative impact on the host UART’s bit width, going from 1.083us to 1.125us (I would expect 1.085us for 921600). Can you shed any light on this issue?

  • 0
    TI__Guru 56685 points

    Hello Jayden,

    Check out the following app note for some general UART debugging tips to get you started: Solutions to Common eUSCI and USCI Serial Communication Issues on MSP . Its titled focused on MSP430, but the MSP432P4 has the same eUSCI module.

    You also may want to check your clock speeds driving the eUSCI module and coordinate your UART settings with the reference settings found in section 24.3.13 in the TRM for MSP432P4. You will want to make sure your settings have lower error rates if you are getting transmission errors.  You may also want to review your LPM settings as mentioned in section 24.3.14 as well.