Reading a pulsing input

[PeteKnight]

@Bobbyh88

The bit I think I’m going to struggle with is to limit the notification to only once per manoeuvre, as opposed to once every change in signal. I.e gate gets opened 4-5 times a day and each time there is 1 opening manoeuvre, 1 open manoeuvre, 1 closing manoeuvre and then 1 closed manoeuvre. So at a maximum would get 5 x 4 notifications per day.

You should use a flag variable…

Events, Notifications and the use of "Flag" variables

Update 19th May 2022 - you’ll see references to a limit of one event per minute in this tutorial. It appears that this limit has now been removed. I’ve not yet tested this myself, and when I do I’ll update the tutorial to reflect my findings. I’m seeing quite a few posts from people who are finding it difficult to get notifications working in Blynk IoT, and who don’t understand how to use “flag” variables to limit the number of notifications that are sent for any given alert situation. I thoug…

@Bobbyh88

What are the ultimate consequences of using the relay? I.e is it going to interfere with the rest of my board working / not consistently pickup signals?

As I said originally, relays aren’t designed to be pulsed and generally don’t respond well when you do this.
When a relay is energised a solenoid system pulls the contacts closed. All physical switch contacts ‘bounce’ when they are made/broken, resulting in a random stream of rapid make/break events. This is electrical noise, and is particularly prevalent with mechanical relays.
You will struggle to differentiate between the electrical noise pulses, and the actual high/low pulses that you are attempting to decode.
In addition, your relay won’t perform consistently over time. Electrical noise tends to increase as the contacts become dirty, and the mechanical operation will vary as the internal solenoids wears, along with the return spring. So, what works now, with one particular relay, won’t work the same way in future or when the relay is replaced with a different one.

@Bobbyh88

Is this the type of thing?

Maybe. Most of these level shifters are 5v to 3.3v but this one looks like it can tolerate 24v input, but it seems to want an output VCC of 12v. If it will work with a 5v output VCC then you’ll be fine.

Pete.