<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Tomas<div><br></div><div>The FTDI can deliver HW flow control signals RTS/CTS.</div><div>Magnus even connected them to the FPGA. Look at tge schematic.</div><div>But the Oberon system does not map them to IO registers. So, currently you don’t have access to those signals from within Oberon.</div><div><br></div><div>It would be a nice little task to enable CTS/RTS in Oberon. Perhaps have a try.</div><div>You have to modify the UCF</div><div>You have to modify RISC5Top.v</div><div>You have to modify the serial drivers in Oberon<br><br><div dir="ltr">br<br><div>Jörg</div></div><div dir="ltr"><br><blockquote type="cite">Am 22.05.2020 um 20:14 schrieb Magnus Karlsson <magnus@saanlima.com>:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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<div class="moz-cite-prefix">On 5/22/2020 10:32 AM, Tomas Kral
wrote:<br>
</div>
<blockquote type="cite" cite="mid:20200522193210.31d646e5@raspberrypi">
<pre class="moz-quote-pre" wrap="">RS232 is RxD, TxD, and flow control signals (CTS/RTS or DSR), GND.
Minimum of 5 wires/signals.
This is failing me, unless FTDI does some magic. Can we do h/w flow
control over USB?
</pre>
</blockquote>
<p>(I guess the mailing list don't like screen capture images so
here is another try)<br>
</p>
<p>From FTDI web site:</p>
<p><strong>How does RTS/CTS flow control work in an FTDI chip?</strong></p>
<p>FTxxx RTS# pin is an output. It should be connected to the CTS#
input pin of the device at the other end of the UART link. </p>
<p>If RTS# is logic 0 it is indicating the FTxxx device can accept
more data on the RXD pin. </p>
<p>If RTS# is logic 1 it is indicating the FTxxx device cannot
accept more data. </p>
<p>RTS# changes state when the chip buffer reaches its last 32 bytes
of space to allow time for the external device to stop sending
data to the FTxxx device. </p>
<p>FTxxx CTS# pin is an input. It should be connected to the RTS#
output pin of the device at the other end of the UART link. </p>
<p>If CTS# is logic 0 it is indicating the external device can
accept more data, and the FTxxx will transmit on the TXD pin. </p>
<p>If CTS# is logic 1 it is indicating the external device cannot
accept more data. the FTxxx will stop transmitting within 0~3
characters, depending on what is in the buffer. </p>
<p> <br>
</p>
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