Re: UART connection between ATSAMD20 and ATtiny4313

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: UART connection between ATSAMD20 and ATtiny4313
Date	2023-04-28 09:48 +0200
Organization	A noiseless patient Spider
Message-ID	<u2ftob$2bnd0$5@dont-email.me> (permalink)
References	(2 earlier) <u2c2eu$1hfgr$2@dont-email.me> <3400c428-350a-4826-adc8-df2c6105fc8bn@googlegroups.com> <u2dbn7$1q74v$1@dont-email.me> <slrnu4ku3q.qb0.andrews@sdf.org> <fbdc8ee3-eaa9-4042-b4ca-d86f482f9d2dn@googlegroups.com>

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On 27/04/2023 18:22, Rick C wrote:
> On Thursday, April 27, 2023 at 9:28:33 AM UTC-4, Andrew Smallshaw wrote:
>> On 2023-04-27, pozz <pozz...@gmail.com> wrote:
>>> Il 27/04/2023 02:10, Rick C ha scritto:
>>>
>>>> I don't see where you have a choice, unless you want to add a crystal to the ATtiny. Can the SAM chip send a clock? You can use an SPI port instead of a UART, or just send a clock to use for the bit rate clock in the UART?
>>>
>>> No, this isn't an option.
>> The other option would be to adopt a Manchester-encoded (self
>> clocking) signal. Wouldn't be true RS485 but would pass through
>> transceivers and cabling at sensible baud rates. Manchester coding
>> is fine provided the clocks are within 2:1 of each other. You will
>> need to bit-bang the interface though, the UART won't handle it.
> 
> What about Manchester encoding is not RS-485?  That's just an electrical interface standard, no?
> 

Technically, you are correct.  In reality, the term "RS-485" is usually 
used to mean "UART signalling on an RS-485 bus" - any other kind of 
signalling (such as Manchester encoding) would be specified explicitly. 
It's good to be technically accurate, but also good to consider less 
accurate common usage of terms.

> But that is a great idea... if the hardware will accommodate it.  Or
> this can be done in the UART using a faster clock and synchronous
> mode.  Send characters with one data bit per character, the
> Manchester encoded bit, x0F or xF0.  It would not be terribly hard to
> decode the data in software.. possibly.  I believe you align to the
> transition that is always present mid-cell, then look for the
> presence/absence of the other transition.  The OP talked about the
> "small" processor being program space constrained, but again, this is
> not a lot of code... maybe.  So maybe this will be too much.  But it
> would solve the clocking issue.  Then again, so would a crystal.
> 

Not all microcontroller UARTs have synchronous modes.  Receiving or 
sending Manchester encoded data with a UART is fiddly because of the 
start and stop bits of UART, so it is often done by bit-banging. 
Whether or not that suits the OP, only he can say.

Thread

UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-04-26 16:56 +0200
  Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-26 17:57 +0200
    Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-04-26 22:40 +0200
      Re: UART connection between ATSAMD20 and ATtiny4313 Grant Edwards <invalid@invalid.invalid> - 2023-04-26 21:00 +0000
        Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-26 17:20 -0700
        Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-04-27 10:15 +0200
  Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-26 09:26 -0700
    Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-04-26 22:44 +0200
      Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-26 17:10 -0700
        Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-27 09:17 +0200
        Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-04-27 10:28 +0200
          Re: UART connection between ATSAMD20 and ATtiny4313 Andrew Smallshaw <andrews@sdf.org> - 2023-04-27 13:28 +0000
            Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-27 09:22 -0700
              Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-28 09:48 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 01:55 -0700
            Re: UART connection between ATSAMD20 and ATtiny4313 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-27 20:18 +0300
              Re: UART connection between ATSAMD20 and ATtiny4313 Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 23:03 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-28 09:58 +0300
              Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-27 17:45 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-28 10:00 +0300
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 00:21 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-28 11:43 +0300
                Re: UART connection between ATSAMD20 and ATtiny4313 Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 11:10 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-28 17:26 +0300
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 02:14 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 02:19 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-28 14:51 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 16:41 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-29 18:01 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-30 02:37 -0700
          Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-27 09:02 -0700
            Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-28 15:01 +0200
              Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-28 16:44 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-04-29 17:59 +0200
  Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-03 18:16 +0200
    Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-03 09:40 -0700
      Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-04 10:34 +0200
        Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-05-04 12:31 +0200
          Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-05 10:51 +0200
            Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-05-05 12:59 +0200
              Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-05 18:01 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Dimiter_Popoff <dp@tgi-sci.com> - 2023-05-05 19:52 +0300
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-07 23:20 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-05 11:37 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-07 23:21 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-05-08 08:37 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-08 09:24 +0200
            Re: UART connection between ATSAMD20 and ATtiny4313 Grant Edwards <invalid@invalid.invalid> - 2023-05-05 20:16 +0000
              Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-07 23:17 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-07 14:27 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 David Brown <david.brown@hesbynett.no> - 2023-05-08 08:34 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Dimiter_Popoff <dp@tgi-sci.com> - 2023-05-08 13:46 +0300
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-08 09:38 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Grant Edwards <invalid@invalid.invalid> - 2023-05-08 14:12 +0000
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-08 18:13 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-08 11:39 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-09 17:04 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-09 14:32 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-10 08:55 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Grant Edwards <invalid@invalid.invalid> - 2023-05-08 19:09 +0000
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-09 17:08 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-08 07:32 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-08 18:27 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-08 11:52 -0700
                Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-09 16:52 +0200
                Re: UART connection between ATSAMD20 and ATtiny4313 Grant Edwards <invalid@invalid.invalid> - 2023-05-09 15:10 +0000
                Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-09 14:29 -0700
        Re: UART connection between ATSAMD20 and ATtiny4313 Rick C <gnuarm.deletethisbit@gmail.com> - 2023-05-04 06:21 -0700
          Re: UART connection between ATSAMD20 and ATtiny4313 pozz <pozzugno@gmail.com> - 2023-05-05 11:02 +0200

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