Thank you
Ok I use RS232.
But I can't read correctly data ,yet😫😢😫😢
Please guide me
When I send "0x052" from pic1 , I received data in pic2 , but it is not
correct
If serial_sw_read(char)) then block
....
lcd_cursor_position(1,5)
print_byte_hex(lcd, char) -- ====> print 2B
lcd_cursor_position(1,10)
lcd = char. --. ====> Print +
......
On Wednesday, April 21, 2021 at 10:02:54 AM UTC+4:30 Kiste wrote:
> Thanks for the additional information, 800m is something very different
> from 20m ;-)
>
> I can imagine that 20m at 5V ground-referenced is doable, but when you're
> starting, better stick to the specifications and try your luck when you
> have a bit of experience.
>
> I myself am at a similar project, like 15 meter, and I want to use as
> little standby current as possible, and no twisted pairs. It's
> uni-directional, with constant-current pullup at the receiver and optically
> isolated pulldown at the sender with 1200 baud... First test of the concept
> in a few days ;-)
>
> If standby current was of no concern, I'd use RS422 or RS485
> drivers/receivers, true RS232 is old-fashioned and needs to many components.
>
>
> Greets,
> Kiste
>
> Am Mittwoch, 21. April 2021, 07:02:46 MESZ hat vsurducan <
> [email protected]> Folgendes geschrieben:
>
>
>
>
>
> Oliver, I remember the problems I had with an EIA232 with +/-8V output
> running at 800m at 9600bps. Everything works until due the transceiver
> heating the voltage dropped at +/-7.6V...:)
> The length is given by the voltage at the level converter of the
> transmitter output. All level converters with charge pumps are not able to
> give more than +/-8V...+/-10V in the happiest circumstances.
> Oldest/goldest EIA232 worked at +/-25V up to 2km.
> For 20m you do noy need any level converter at the output of your PIC,
> just a twisted pair RX-GND TX-GND (CAT5 ethernet cable is perfect) and an
> open collector transmitter ( a gate) with pull-up resistor in the receiver
> end (at 20m distance from the transmitter).
> However Majid, I think you need first to learn jal and for that there is
> a learning curve which has to be passed....
> Please start with the examples, compile them, make them run, modify them
> as you wish and post only when nothing works for you after three days of
> trying...this will help you more than you may believe right now...
> best wishes
>
> On Wed, Apr 21, 2021 at 7:28 AM 'Oliver Seitz' via jallib <
> [email protected]> wrote:
> > Hi Majid,
> >
> > SPI is designed for centimeters, I don't think it can work reliably over
> 20 meters.
> >
> > RS232 at 9600 baud is ok for 150 meters, if you're using real RS232
> drivers and receivers like from the MAX232 series. The PIC controller does
> not have RS232, it has a usart which handles the NRZ protocol. This
> protocol is best known as being used by the RS232 interface. Therefore the
> protocol itself is commonly (but wrongly) referred to as "RS232"
> >
> > RS232 uses negative voltages as a symbolic "1" and positive voltages for
> "0". At the receiving side, the voltage must at least go higher than +3V
> for "0" and lower than -3V for "1". At the sending side, voltages from up
> to +15V and down to -15V are used.
> >
> > So, to answer your question in two simple sentences: RS232 is ok for the
> job. But RS232 is not what comes out of the controller.
> >
> > Greets,
> > Kiste
> >
> >
> >
> >
> > Am Dienstag, 20. April 2021, 21:56:34 MESZ hat majid ebru <
> [email protected]> Folgendes geschrieben:
> >
> >
> >
> >
> >
> > can i ask another question??
> >
> > if it is 20 meter distance between PICs , i should use RS232 or SPI?
> >
> > so sorry and thanks a lot
> >
> > majid ebru در تاریخ سهشنبه ۲۰ آوریل ۲۰۲۱ ساعت
> >
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