Hi all!
I've a problem with my Arduino Micro and the Keypad library.
The circuit works great if you press only one button per time.
The problem is when you press more than one. Diodes are already there.
Here's the schematic of the circuit:
As you can see, when one of the inputs of the AND port will go down, then the transistor will close the circuit between row and colum.
I can share the code if you need.
Thank you in advance.
What is this circuitry showing? What is it supposed to do?
Hi,
please, read this information.
Hi Railroader,
the circuit is supposed to manage 4 panels with 4 sensor each one (so we have 16 sensors) that work like a switch to the gnd.
Inputs are pulled up to 5 volts with a resistor array (not in the schematics picture). So if one of them is pressed, the output of the AND port goes low, the NOT output goes HIGH and we have the saturation of the transistor.
I need to press up to 4 panels at the same time... I wonder if the output current of the NOT IC is a problem if I press more than 2/3 pads...
From a quick look , there may be an issue that when the transistors are “ off” , then inputs on the right are open circuit and may be able to take on a random value ( if they are inputs )
The transistors are not the same as a simple switch and can’t be used to just connect two points together.
Also if the right hand side of a diode is high , other transistors won’t be able to switch as the Vbe will never be above .6 volts .
A completely schematic would be a lot clearer.
Are we to understand there are 4 lots of that circuit?
Why are there diodes in the emitters? That will mean the lowest the collector can go is about 0V8, is that okay? (Assuming that the emitter connections are 0V, which is not at all clear).
Diodes are in the wrong place. Should be in the collector connections, not the emitters.
220 Ohm resistors are wrong - should be about 10k or 22k.
A 74HC4066 for four "buttons" or a 74HC4052 would be more sensible than transistors.
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