Keypad control

Question

I am trying to figure out how I can hack into a keypad to simulate keypresses. I do testing on an assembly that requires me to press a series of buttons and wait for a response from the device. After there would be another sequence of button presses. so on and so on till the unit has gone through all its tests. So I would like to create something that had multiple buttons so I could press on button to initiate one sequence then additional buttons to perform the remaining sequences. all in total I would say no more that 5 buttons would be needed. for different sequences. The Keypad that I am controlling has LEDs on it as well so it would be nice to be able to monitor those as well and have it show a pass fail display. But that could be for the future rev. I'm mainly concerned on just eliminating the thousands of button pushes that I will have to do. Initially I was thinking that I could have an Arduino send out info to trigger a set of 595 chips (to eliminate the overuse of output pins) to some 4066 chips. which would make the connections that simulate the keypresses. Is this the right direction and if so could someone help me with the code? I am very new at this and could use some guidance.

Thank you for you time and consideration,

Ken Johnson

dougw · Answer

How many buttons are on the keypad and how many pins are on the header?

Would an arduino mega with 54 I/O pins be enough to avoid shift registers?

There are some products that emulate keypad sequences, but it doesn't sound exactly like what you need:

PoKeys55T

PoKeys57U

PoKeys57E

shabaz · Answer

Hi Ken,

Is the device under test using a USB keyboard? If so, is there a chance to replace it, or to attach another one to a spare USB port?

If so, you could use something programmable like this (this is just an example): Building a USB Keypad: A Mini-Project

The code there is fairly easy to follow and make modifications to send key sequences etc. The hardware is straightforward, just 8 wires need soldering.

kenj79 · Answer

There isn’t a keyboard attached to the unit. The unit has a membrane keypad array attached via a header and I have to tie into the header in order to simulate the key presses. shorting the two pins that are done when a button is pressed. Then for the next subsequent keypresses. Once that sequence has finished I would need it to wait for the next command. to start a new sequence. It would need more buttons to initiate commands.

Ken

shabaz · Answer

I see.. in that case the shift-reg method you suggest sounds appropriate. The 595 is popular for driving LED arrays, so there will be example code that could be helpful. This URL looks useful:

https://www.arduino.cc/en/Tutorial/ShiftOut

Keypad control

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