[fpc-pascal] (OT) Re: How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
el.es.cr at gmail.com
Thu Jul 4 12:52:49 CEST 2013
On 04/07/2013 11:08, Dennis Poon wrote:
> thanks. I am not using the fpc email as it seems off topic.
> May I know the exact brand and model number of the adapter you used?
> I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to
> connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to
> set that adapter into half-duplex translation mode.
(apparently it went into FPC list anyway)
For RS485 adaptation, use a MAX232 like chip (to convert +-12 to ttl)
and then a RS485 transceiver chip;
A MAX232 has 4 [IIRC] level changers, 2 in each direction; so you can
use one pair to convert tx/rx, and one of the remaining ones in 232-ttl direction,
to convert one RS232 signal to switch the RS485 trx into 'sending' mode;
Of course you need an additional +5V supply to the above too.
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