<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="">Shane, <div class=""><br class=""></div><div class="">Wow, I did not know this was an option. The only problem is that I believe the only interrupt pins that can wake the Arduino from sleep are the D2 and D3 pins and this requires Analog pins. Please correct me if I am missing something. </div><div class=""><br class=""></div><div class="">I can see this being useful in other applications it even supports hysteresis. </div><div class=""><br class=""></div><div class="">Thanks,</div><div class=""><br class=""></div><div class="">Chip</div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jun 21, 2016, at 9:49 PM, Shane Trent <<a href="mailto:shanedtrent@gmail.com" class="">shanedtrent@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Chip,<div class=""><br class=""></div><div class="">Have you considered tying the range finder output to one of the AVR's comparator inputs and a setting the trip point with a pot voltage divider on the other terminal?</div><div class=""><br class=""></div><div class=""><a href="https://www.avrprogrammers.com/howto/comparator" class="">https://www.avrprogrammers.com/howto/comparator</a><br class=""></div><div class=""><br class=""></div><div class="">Shane</div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Tue, Jun 21, 2016 at 8:49 PM Chip McClelland via TriEmbed <<a href="mailto:triembed@triembed.org" class="">triembed@triembed.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="">All, <div class=""><br class=""></div><div class="">OK, before you say it, yes, I first consulted Google before sending this note. I have not worked with these devices before and the latch operation is the part that I find most confusing. The best device I could find was the <a href="https://datasheets.maximintegrated.com/en/ds/MAX9140-MAX9144.pdf" target="_blank" class="">MAX9141</a> but the operation of the latch in figure 2 was not what I expected. </div><div class=""><br class=""></div><div class="">I am looking for a simple circuit which will do the following:</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Powered, Vcc, by either 3.3V or 5V and should not consume more than 100uA.</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Connect to the analog output (ranges from 0 to Vcc) of my <a href="http://www.maxbotix.com/Ultrasonic_Sensors/MB7363.htm" target="_blank" class="">Ultrasonic Range Finder</a> with a high input impedance - potentially with a low-pass filter - we will see.</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Allow me to set a “trigger threshold” ( 0 to Vcc) using a potentiometer </div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Compare the input to the trigger and provide a latched digital “high” when the input exceeds the threshold</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- This signal will wake the micro controller using a hardware interrupt and trigger an interrupt routine.</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- The comparator will hold the line “high” input until cleared by the micro controller</div><div class=""><br class=""></div><div class="">Anyone who has a few minutes to take a look please let me know:</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Is the part I found the right one?</div><div class=""><span style="white-space:pre-wrap" class=""> </span>- Is there a better solution - perhaps using discrete components?</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Thank you,</div><div class=""><br class=""></div><div class="">Chip</div><div class=""><br class=""></div></div>_______________________________________________<br class="">
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