Im having a problem using my membrane keypad.
This thread only about the keypad, the code to use it has checked out good.
I have this keypad:
http://newzealand.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0130381
While running my program, it appears that this keypad is giving false readings. eg. saying their are buttons pressed when Non are pressed, and constantly changing without user input. When i jiggle the keypad around the numbers its outputing changes rapidly. When i put my finger around the loom, it changes rapidly. Im thinking there is a capacitance / inductance problem between the loom wires.
Im putting approx 15mA @ 4.5V onto the lines.
And the lines not being used are grounded via a 10K resistor.
The resistance on each line is 30 Ohms when a key is pressed.
I have taken the keypad off, and used wires across the appropriate pins and the code gives the correct readings onto my display that it should. But when the keypad is connected, false readings occur.
Im using a 28X1, and im using the digital inputs of portA to read IN.
Has anyone come across this problem before?
Does have a theory on why this might be happening?
Does anyone have a possible solution on this?
If you need more info, please ask.
This thread only about the keypad, the code to use it has checked out good.
I have this keypad:
http://newzealand.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0130381
While running my program, it appears that this keypad is giving false readings. eg. saying their are buttons pressed when Non are pressed, and constantly changing without user input. When i jiggle the keypad around the numbers its outputing changes rapidly. When i put my finger around the loom, it changes rapidly. Im thinking there is a capacitance / inductance problem between the loom wires.
Im putting approx 15mA @ 4.5V onto the lines.
And the lines not being used are grounded via a 10K resistor.
The resistance on each line is 30 Ohms when a key is pressed.
I have taken the keypad off, and used wires across the appropriate pins and the code gives the correct readings onto my display that it should. But when the keypad is connected, false readings occur.
Im using a 28X1, and im using the digital inputs of portA to read IN.
Has anyone come across this problem before?
Does have a theory on why this might be happening?
Does anyone have a possible solution on this?
If you need more info, please ask.