<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 29 Apr 2017, at 1:07 AM, Michael Balzer <<a href="mailto:dexter@expeedo.de" class="">dexter@expeedo.de</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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Currently the Think uses two GPIO pins, the Leaf one, and the Twizy
eight (4 in + 4 out for the SimpleConsole).<br class="">
<br class="">
This is the only SPI bus left for general purpose extensions?<br class="">
<br class="">
But as the MAX7317 is 16 bit and supports daisy chaining, it will
still be possible to add a touch screen or other I/O extensions to
it?<br class="">
<br class="">
If it doesn't create problems for "higher level" addons it's got my
vote as well.<br class="">
<br class="">
Regards,<br class="">
Michael<br class="">
<br class="">
<br class="">
<div class="moz-cite-prefix">Am 28.04.2017 um 07:02 schrieb Mark
Webb-Johnson:<br class="">
</div>
<blockquote cite="mid:D7572C17-D9C1-407B-BBD6-B269EBD88280@webb-johnson.net" type="cite" class="">
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<div class="">Copying OVMS developers in on this, as it is an
interesting question.</div>
<div class=""><br class="">
</div>
<div class="">Free pins are very tight on the OVMS v3. We’ve added
so much as standard (extra flash, SD card, 3 CAN buses, etc,
etc) that there is not much free.</div>
<div class=""><br class="">
</div>
<div class="">In the first draft design (shown on the attached
pictures), we had two general GPIO pins free - EXP_1 and EXP_2.
However, working with Espressif (the makers of the ESP-32 MCU)
it seems that the best and simplest way to use external flash is
to change the SPI bus chip select line and add an external flash
on that. If we do that, we need one more pin, and that means
goodbye EXP_2.</div>
<div class=""><br class="">
</div>
<div class="">So, only one free GPIO pin - EXP_1.</div>
<div class=""><br class="">
</div>
<div class="">We do have two internal expansion slots where
piggy-back boards can be plugged (one for the optional modem and
one free for general use). These use standard 0.1” SIP
connectors (two 1x10), so very easy to breadboard. For those, we
have EXP_1 on the attached diagram.</div>
<div class=""><br class="">
</div>
<div class="">These pins are also available on a DA26 female
expansion connector on the side of the module (so you can use
them directly).</div>
<div class=""><br class="">
</div>
<div class="">There is also a SW_12V switched 12volt supply on the
DA26 female expansion connector.</div>
<div class=""><br class="">
</div>
<div class="">So, the short answer is if you just need a single
GPIO, that is available either internally of externally as
EXP_1. If you need a second, you could probably use the SW_12V
as well.</div>
<div class=""><br class="">
</div>
<blockquote style="margin: 0 0 0 40px; border: none; padding:
0px;" class="">
<div class=""><u class=""><b class="">I/O expansion</b></u></div>
<div class=""><br class="">
</div>
</blockquote>
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0px;" class="">
<div class="">If you need more than two, then you could use a
SPI bus I/O expander, probably on one of the internal
expansion slots, and use EXP_1 to drive that. The MAX7317 is
suitable.</div>
<div class=""><br class="">
</div>
<div class="">In the first draft design for OVMS v3, we have
three relatively unused simple I/O pins</div>
</blockquote>
<div class="">
<ul class="MailOutline">
<ul class="">
<li class="">MDM_EN - UART 2, modem enable (used to reset
the modem - very infrequent)</li>
<li class="">SW_CTL - Switched 12V control signal (used to
turn on/off the external 12V - very infrequent)</li>
<li class="">EXP_1 - expansion pin</li>
</ul>
</ul>
</div>
<blockquote style="margin: 0 0 0 40px; border: none; padding:
0px;" class="">
<div class=""><br class="">
</div>
<div class="">What I’ve been considering is adding a MAX7317 as
standard, using EXP_1 to drive that (along with the normal SPI
bus used for two of the CAN buses), then moving MDM_EN and
SW_CTL to that. The MAX7317 has 10 I/O ports, so if we did
that, we’d get 8 free I/O ports from the MAX7317 as well as 2
direct off the ESP32 MCU.</div>
<div class=""><br class="">
</div>
<div class="">I’m 99% decided to do that, but just trying to
work out cost impact and if there is enough room on the board
to actually fit it in.</div>
</blockquote>
<div class=""><br class="">
</div>
<div class="">Regards, Mark.</div>
<div class=""><br class="">
</div>
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<blockquote type="cite" class="">
<div class="">On 28 Apr 2017, at 3:04 AM, Wolfgang Jenne <<a moz-do-not-send="true" href="mailto:wolfi@spider.li" class="">wolfi@spider.li</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="" style="font-family: Helvetica; font-size:
24px; font-style: normal; font-variant-caps: normal;
font-weight: normal; letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none;
white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;">One question: The OVMS v3
module: is it going to have some digital inputs somehow?</div>
<div class="" style="font-family: Helvetica; font-size:
24px; font-style: normal; font-variant-caps: normal;
font-weight: normal; letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none;
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</div>
<div class="" style="font-family: Helvetica; font-size:
24px; font-style: normal; font-variant-caps: normal;
font-weight: normal; letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none;
white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;">thanks,</div>
<div class="" style="font-family: Helvetica; font-size:
24px; font-style: normal; font-variant-caps: normal;
font-weight: normal; letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none;
white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;">Wolfgang</div>
</div>
</blockquote>
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</pre>
</blockquote>
<br class="">
<pre class="moz-signature" cols="72">--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
</pre>
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