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Topic: TSSP4038 in parallel (Read 100 times) previous topic - next topic

koston411

I want to use the TSSP4038 in a beam breaker.

I use several receivers but don't really care about locating with one is triggered. I thought I would mount them in parallel to use only 1 pin of the Arduino. So far I have 10 receivers, maybe 20 soon.

From what I understand several TSSP40xx in parallel work as an "AND" gate (you have to break all beams together to get the signal HIGH). This is not what I want.

I'm looking to receive a signal if any one of the TSSP40xx gets its beam broken.

Any idea?

Grumpy_Mike

#1
Sep 15, 2020, 09:57 am Last Edit: Sep 15, 2020, 10:04 am by Grumpy_Mike
Use several NAND gates to combine these signals. You can get gates with up to 8 inputs. Then invert the outputs and feed these into more NAND gates until you get down to one output. Use the 74HCT series of gates like this one.
https://assets.nexperia.com/documents/data-sheet/74HC_HCT30.pdf

Wawa

Yes, you can put many (open collector) receiver outputs in parallel.
The limitation is the absolute max 5mA sink current of each receiver.

You can can calculate that from the 33k internal pull up resistor and the supply voltage.
20 receivers would be 5volt/(33k/20)= 3mA.
Above that amount I would think of using a second Arduino pin.
Leo..

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