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Hi,
I want to put a FTDI-UART
in parallel with a RS-232 transceiver. As
FTDI I’m using a FT2232D with JTAG (Port-A) and UART (Port-B) configuration. As
transceiver I was choosing MAX3223 since it has an INVALID# output.
I do only have one UART-pair free at the CPU so I want them kind of
multiplexed. Only one of these two interfaces is used at the same time.
My plan is a wired-or for the transmitter. But for the receiver the FTDI can be
in set to a weak pull down mode but somehow I have to cut-off the MAX3223 receiver
output since it will have a high-level. Do you guys think it’s possible to add
a buffer after MAX3223’s receiver output, which is enabled/disabled by the
INVALID# pin?
So if no valid RS232 signals is detected the MAX3223 output won’t be connected
to the CPU. The aim is to use FTDI-JTAG capability and RS-232 as UART in parallel.
Best regards
Guenther
