[TriEmbed] I need a circuit that can do this.....

[Chip McClelland]

Shane, 

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.  

I can see this being useful in other applications it even supports hysteresis.  

Thanks,

Chip


> On Jun 21, 2016, at 9:49 PM, Shane Trent <shanedtrent at gmail.com> wrote:
> 
> Chip,
> 
> 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?
> 
> https://www.avrprogrammers.com/howto/comparator <https://www.avrprogrammers.com/howto/comparator>
> 
> Shane
> 
> On Tue, Jun 21, 2016 at 8:49 PM Chip McClelland via TriEmbed <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
> All, 
> 
> 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 MAX9141 <https://datasheets.maximintegrated.com/en/ds/MAX9140-MAX9144.pdf> but the operation of the latch in figure 2 was not what I expected.  
> 
> I am looking for a simple circuit which will do the following:
> 	- Powered, Vcc, by either 3.3V or 5V and should not consume more than 100uA.
> 	- Connect to the analog output  (ranges from 0 to Vcc) of my Ultrasonic Range Finder <http://www.maxbotix.com/Ultrasonic_Sensors/MB7363.htm> with a high input impedance - potentially with a low-pass filter - we will see.
> 	- Allow me to set a “trigger threshold” ( 0 to Vcc) using a potentiometer 
> 	- Compare the input to the trigger and provide a latched digital “high” when the input exceeds the threshold
> 	- This signal will wake the micro controller using a hardware interrupt and trigger an interrupt routine.
> 	- The comparator will hold the line “high” input until cleared by the micro controller
> 
> Anyone who has a few minutes to take a look please let me know:
> 	- Is the part I found the right one?
> 	- Is there a better solution - perhaps using discrete components?
> 
> 
> Thank you,
> 
> Chip
> 
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