<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><br><br><br></div><div><br>On 08 Aug 2015, at 00:34, john slee <<a href="mailto:indigoid@oldcorollas.org">indigoid@oldcorollas.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On 7 August 2015 at 17:04, Rick Jansen <span dir="ltr"><<a href="mailto:rick.jansen@xs4all.nl" target="_blank">rick.jansen@xs4all.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font face="Helvetica, Arial, sans-serif">I2C may be relatively
slow, but this is a user-interface thingy, and we humans are very
very slow, compared to I2C. Well, I am.<br>
I'll see how I fare. I really like I/O extension of the Arduino
with the PCF8574 chips, and the way that one pin change gives you
an interrupt. </font><font face="Helvetica, Arial, sans-serif"><font face="Helvetica, Arial, sans-serif"></font>(Shift registers
don't do that.) <br></font></blockquote></div><br>If you're using the PCF8574 you may also want to have a look at Microchip's MCP23017 (i2c) and MCP23S17 (SPI). Other than the bus interface the i2c and SPI versions are very similar. </div><div class="gmail_extra"><br></div><div class="gmail_extra">John</div></div>
</div></blockquote><br><div>Ok! Difference is that <span style="background-color: rgba(255, 255, 255, 0);">MCP23017 is more versatile with output current, it can both source and sink 25mA per pin, where the PCF can only sink current on sn output pin.</span></div><div><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div><div><span style="background-color: rgba(255, 255, 255, 0);">Thanks,</span></div><div><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div><div><span style="background-color: rgba(255, 255, 255, 0);">rick</span></div></body></html>