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question about BOOT ROM SCI mode

Snaku Lee1
Prodigy 140 points

Part Number: TMS320F280049C

Hi, 

I try to send data to F280049 in its SCI boot ROM mode from another MCU, the UART baudrate is 57600bps. I check my F280049's BOOTPIN_CONFIG and BOOTDEF are all 0xFFFF, so F280049 should use default setting for SCI BOOT mode selection, i.e. GPIO24 is low, GPIO32 is high for SCI boot. And GPIO28, GPIO29 should be the default SCI interface. But after reset, the GPIO29 (SCI TX) doesn't echo data which I sent.

Do i miss something cause F280049 doesn't enter SCI boot mode?

< waveform measure by a scope >

< waveform measure by a logical analyzer >

  • 0
    Prodigy 140 points

    Hi,

    I find my problem is that the C28x SCI autobaud detection used in SCI boot needs the first byte is ASCII 'A' or 'a'.

    After I add a 'A' at the first byte, the C28x can echo a 'A' back to me.

    But there is an little issue is that the GPIO29 enable pull-up seems like after autobuad locked, it is not the same as the SCI BOOT flow char " Figure 4-5. Overview of SCI Boot Function" in F280049 reference manual. 

    Regards,

    Snaku