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

[Shane Trent]

Chip,

I believe you can also set the comparator to trigger an interrupt. The
example code at the link shows them using the comparator interrupt.

Shane

On Tue, Jun 21, 2016 at 9:59 PM Chip McClelland <chip at mcclellands.org>
wrote:

> 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
>
> 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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