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

[Shane Trent]

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

Shane

On Tue, Jun 21, 2016 at 8:49 PM Chip McClelland via TriEmbed <
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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