SC18IM704-EVB GPIO6 & 7

[jj100126]

Can anyone explain why GPIO6 and 7 of the SC18 in the evaluation board are connected to the T1IN and R2OUT of the SP3232, respectively? And also, why the DB9 connector is connected in such a way? Like why pin 1 and 6 are shorted, pin 7 and 8 are connected to R2IN of SP232, pin 4 is open, and pin 9 is connected to T1OUT?

[guoweisun]

Those are the nRTS and nCTS. Normally, they are not use but you can use nCTS to wake up SC18IM704 or use nRTS to wake up the other device. You can also use them for hardware flow control to prevent the FIFO from overflow (google UART hardware flow control).

[jj100126]

so nRTS and nCTS are connected as an input to the SP3232, with its corresponding output to GPIO7, but what about GPIO6? Why is it paired with pin 9 of the DB9?