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microA1 Serial port(s)

Posted: Thu Feb 11, 2021 10:45 am
by migthymax
Hi,

I'm trying to establish a communication link with another computer via the microA1 serial port. Without any luck up till now. And it behaves somehow
strange. My setup is actually the same as described here: https://www.amigans.net/modules/xforum/ ... ic_id=4985

Regardless what i do nothing happens at the other side, when sending data via the serial port. I tried to let the kernel output via the serial port, nothing. I even compiled a simple program to just send a fix string via the first serial port. Nothing. I checked the baud, etc settings. Nothing happens.

Sometimes trying to send something via the serial port the system hangs. But because it isn't reproducible i think it just another issue.

So i started to run the 'post serialtest' on the u-boot shell. Regardless if run with or without the 'null-modem-cable plug', it hangs.

Is the serial port of the mictoA1 supported to work? And sometimes i read there is a second serial port (At least opening the unit 1 of the serial.device, doesn't fail), where is the second port located?

regards

Re: microA1 Serial port(s)

Posted: Sun Feb 14, 2021 3:07 pm
by migthymax
The original author if the question https://www.amigans.net/modules/xforum/ ... ic_id=4985, was
so kind an answered me on a PM. Even than, no solution was found.

Thus so little bit different question: Anyone ever had success with using the serial port of the microA1? It seems that no one very had success
in using it.

BTW even U-Boot does write anything out on the serial port, at least it is supposed to do.

Re: microA1 Serial port(s)

Posted: Thu Feb 18, 2021 10:50 am
by smf
Ofcourse the serial port is supposed to work :)

The devs and betatesters use it all the time.

Re: microA1 Serial port(s)

Posted: Mon Apr 12, 2021 4:15 pm
by xenic
I don't have a microA1 any more but when I had one years ago I connected a "header to female 9 pin" adapter to the internal serial serial header so I could use that serial port with a dialup modem and it worked for years. Unlike some newer NG Amigas the µA1 uses all serial pins which allows hardware flow control. On newer systems I think you need to use software flow control. Maybe your problem relates to flow control or baud rate. I don't know if this information will help but I thought I'd let you know that I did use µA1 serial with a dialup modem.

Re: microA1 Serial port(s)

Posted: Sun May 02, 2021 2:09 pm
by migthymax
Well after your post, i started to measure the pins of the serial port, so to see if anything is happening and with what kind of voltage. My thought was that it mighty be only TTL output levels, but that wasn't the case.
But you explicitly mention hardware handshake, so i took a look at the other side of the serial communication link. Up till now i only used serial-to-usb adapter on a mac. So i connected a windows pc with a built in serial port. In the device manager of windows it is still show as a serial-to-usb serial port, but anyway, i got some visible symbols, that the amiga is actually sending something. The displayed symbols were all scambled and not correctly shown, even that baud etc was correctly set. So i tried my two usb-to-serial dongles on windows, any they behaved like on the mac, receiving nothing.
So in regards to, that the build in serial port was somehow a serial-usb-style interface, i think a "real" RS-232C port on computer is needed to actually receive something from the amiga. But nevertheless i can confirm that the on board serial port of the microA1 is working. I still need to find matching counterpart to see what is saying.

Re: microA1 Serial port(s)

Posted: Sun May 02, 2021 3:15 pm
by xenic
migthymax wrote: Sun May 02, 2021 2:09 pm So in regards to, that the build in serial port was somehow a serial-usb-style interface, i think a "real" RS-232C port on computer is needed to actually receive something from the amiga. But nevertheless i can confirm that the on board serial port of the microA1 is working. I still need to find matching counterpart to see what is saying.
At this point the only thing I can suggest is to read the article here:

https://wiki.amigaos.net/wiki/Advanced_ ... ging_Guide

Re: microA1 Serial port(s) (solved)

Posted: Wed May 12, 2021 10:18 am
by migthymax
I figured it out. I was just about to give it up. But that i stumpled over a forum post on https://www.amigans.net/modules/xforum/ ... t_id=54981 where someone wrote in comment 7 about busted serial post any you should look at the page http://www.ncscaug.us/ua1page1.htm

The page isn't available anymore so i took a chance with web archives https://web.archive.org/web/20081025052 ... 1page1.htm and there the solution was ilustrated. I repeat it here.

The pin layout of the serial port on the microA1 motherboard isn't as documented, it has the following pin layout.

Code: Select all

Key    10   * 5 GND
RI      9 * * 4 DTR
CTS     8 * * 3 TXD
RTS     7 * * 2 RXD
DSR     6 * * 1 DCD  

Knowing that i was able to get the output via the serial port, with any port on the other side, regardless of os and if it is a USB-serial port or something different.