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UART2 CTS problems on OMAP-L138 EVM

John Johnson78925
Prodigy 30 points
Other Parts Discussed in Thread: WL1271, SN74LVC1G125, OMAP-L138, TCA6416

Hi,

I have ZOOM development kit from LOGIC(TMDSEVML138) with WL1271 daughter board.

I need to enable hardware flow control on UART2, so I took PSP linux and made some changes:

da850.c:441

+MUX_CFG(DA850, NUART2_CTS, 0, 28, 15, 4, false)

+MUX_CFG(DA850, NUART2_RTS, 0, 24, 15, 4, false)

da850.c:639

-DA850_UART2_RXD, DA850_UART2_TXD,

+DA850_NUART2_CTS, DA850_NUART2_RTS, DA850_UART2_RXD, DA850_UART2_TXD,

 

Than I connect PC to EVM, open port on both and observe RTS signal work fine, but CTS on EVM is not signaled.

Where did I miss something?

  • 0
    TI__Guru 64510 points

    Have you looked at the schematics of the TMDSEVML138?  The CTS signal on UART2 goes through the RS-232 transceiver device (U24) from the DB9 connector, but immediately goes into a SN74LVC1G125 buffer (U55) which output enable is controlled by a I/O line from the GPIO expander device TCA6416 (U9).  This signal needs to be low to propagate CTS from the RS-232 device to the OMAP-L138.