tag:blogger.com,1999:blog-6238454757421809452.post6924615541927292628..comments2024-01-29T06:22:58.174-05:00Comments on The Raspberry Pi <br>Hobbyist: So Many Inputs, So Few GPIO PinsTed B Halehttp://www.blogger.com/profile/16887056993667506084noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-6238454757421809452.post-71109987244159498972013-06-03T10:24:34.235-04:002013-06-03T10:24:34.235-04:00The PiFace is based on the MCP23S17 SPI GPIO exten...The PiFace is based on the MCP23S17 SPI GPIO extender, which I believe is compatible with TTL levels. As long as the address pins on the 151 are stable (i.e. not changing too quickly) then I see no reason for this not to work.<br />Try testing the 151 without the PiFace. Use a voltmeter to see if the output pin is what you expect for the given inputs.Ted B Halehttps://www.blogger.com/profile/16887056993667506084noreply@blogger.comtag:blogger.com,1999:blog-6238454757421809452.post-23733968749502934702013-05-27T06:20:50.884-04:002013-05-27T06:20:50.884-04:00Very informative blog!
I am trying to use the 74LS...Very informative blog!<br />I am trying to use the 74LS151 with piface, again to increase the number of inputs i can read. I connected pin 5 directly to one of piface inputs, but it seems that reading is not reliable. Any ideas what might me wrong? Is piface input incompatible with TTL levels?maknethttps://www.blogger.com/profile/17362986742954563058noreply@blogger.com