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CC2340R5: 4 wire UART for bootloader

Akihiko Fujinaka
Expert 3465 points
Part Number: CC2340R5
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hello expert,

Can CC2340R5 support 4 wire UART for the bootloader function?

I found the following sentence in RTM but would like to confirm.

 

8.5.1 ROM Serial Bootloader Interfaces

The bootloader communicates with an external device over a 2-pin UART or a 4-pin SPI interface. The

communication protocol and transport layers are described in the following subsections.

Regards,

A.Fujinaka

  • 0
    TI__Genius 12391 points

    Hello A. Fujinaka,

    From what I can read from the TRM and internally the Serial bootloader with UART only uses two UART pins (one UART_RX and one UART_RX):

    See the table below of the available UART configurations: 

    How to select between UART or SPI:

    When accessed, the Serial Bootloader listens on the UART RX and SPI lines for incoming traffic
    to determine which interface will be used. To switch to the other interface, the device must be
    reset using, for example, the reset pin

    UART Auto baud sequence:

    The bootloader waits for what is called the auto baud sequence. This is a two byte alternating
    bit pattern (0x55). If this sequence is received on the UART RX DIO, the bootloader will
    recognize that UART is the desired interface and calculate the baud rate it was sent with. After
    configuring the UART to match the incoming baud rate, a customer is free to send/receive
    normal bootloader commands.
     
    Keep in mind that SysConfig should be used to configure the Serial Bootloader interface before the customer intends to use it. 
    Thanks,
    Alex F
  • 0 in reply to Alex Fager
    TI__Expert 3465 points

    Hello Alex,

    After some communication with my customer, they understand CC2340R5 does not support 4 wire UART on ROM bootloader.

    Next question[

    1. If they will use User bootloader function , they can configure UART as 4 wire ? 

    2. If they will SPI as ROM bootloader , and  use UART for the MCU I/F, they can use 4 wire UART to connect to MCU I/F?  

    Regards,

    A.Fujinaka

  • 0 in reply to Akihiko Fujinaka
    TI__Genius 12391 points

    Hello Fujinaka-san,

    1. I have asked RnD, this it is not clear to me in the TRM if the user defined bootloader uses the same requirements (2 wire UART) or not. 

    2. So to understand the question, the customer will use SPI with the Serial Bootloader, then once the application takes over they will use 4 wire UART in the application? (in sysconfig if you use the hardware UART it defaults to 2 wire UART but if you set use hardware to use none it allows the flow control to be selected which then allows for 4 wire UART). 

    Thanks,
    Alex F

  • 0 in reply to Alex Fager
    TI__Expert 3465 points

    Hello Alex,

    1. Yes, please provide answer from RnD.

    2. Your understanding is correct.

    Regards,

    A.Fujinaka

  • 0 in reply to Akihiko Fujinaka
    TI__Genius 12391 points

    Hello Fujinaka-san,

    1. RnD responded, the customer can you any configuration they like with the user bootloader (so in this example they can use 4 wire UART), however the user bootloader is ultimately dependent on how the customer codes and configures it. 

    2. This is not an issue and is currently possible.