[fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
dennis at avidsoft.com.hk
Thu Jul 4 12:08:10 CEST 2013
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.
Luca Olivetti wrote:
> Al 04/07/13 11:16, En/na Dennis Poon ha escrit:
>>> With RS-485 hardware you can - and supposedly need to - do
>>> "half-duplex with output enable", if your hardware provides this.
>> After days of google search, I am afraid the bcm2835, the Soc of
>> Raspberry Pi (the hardware I have to use) does not provide this hardware
>> support :-(
>> It states that it does not even support interrupt. Polling is the only
>> way for events :-(
> If that's true, you could use an usb to rs485 adapter, most of those do
> the tx/rx switching automatically, so you just see a "normal" serial
> port (of course you'll have to manage the high level protocol yourself).
> I've mostly used them in 422 mode (4 wires/full duplex) but I used one
> of them once in rs485 mode (2 wires/half duplex).
> IIRC the brand was VSCom.
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