Hi!
I hope anyone can help me with this issue. I have a 4x4 keypad connected with a decoder (MM94C922) and the manner in which is connected is exactly as pictured on the datasheet on page 8. The only data sheet that I have from the keypad is their pinouts (data sheet attached).
I've connected pin 1 from keypad to pin2 of the decoder
pin 2 '' '' '' pin3 '' '' ''
pin 3 pin7
pin 4 pin4
pin 5 pin8
pin 6 pin10
pin 7 pin11
pin 8 pin1
finally i connected pin 9 of decoder to ground and Vcc to 3.3V. The capacitors I put .1uF for oscillator (pin5) and 22nF for keypad bounce mask (pin 6).
The problem that I am having is that I'm measuring the voltage out of the decoder outputs and it seems that the voltages are bouncing all over the place..it only remains stable when I hold down a key but when I just press it, depending on the key, the output goes to 3 Volts and just oscillates down to 200mV and at one point jumps to 1.2V. These outputs are to be connected to a PIC, but according to the software it is detecting that the first two numbers of columns 1 and 3 are giving same 4 binary input The same goes for the first two numbers of columns 2 and 4.
I'm confused I thought the encoder was suppose to output binary numbers from 0000 to 1111 where each key holds a respective binary representation. Please help me
I hope anyone can help me with this issue. I have a 4x4 keypad connected with a decoder (MM94C922) and the manner in which is connected is exactly as pictured on the datasheet on page 8. The only data sheet that I have from the keypad is their pinouts (data sheet attached).
I've connected pin 1 from keypad to pin2 of the decoder
pin 2 '' '' '' pin3 '' '' ''
pin 3 pin7
pin 4 pin4
pin 5 pin8
pin 6 pin10
pin 7 pin11
pin 8 pin1
finally i connected pin 9 of decoder to ground and Vcc to 3.3V. The capacitors I put .1uF for oscillator (pin5) and 22nF for keypad bounce mask (pin 6).
The problem that I am having is that I'm measuring the voltage out of the decoder outputs and it seems that the voltages are bouncing all over the place..it only remains stable when I hold down a key but when I just press it, depending on the key, the output goes to 3 Volts and just oscillates down to 200mV and at one point jumps to 1.2V. These outputs are to be connected to a PIC, but according to the software it is detecting that the first two numbers of columns 1 and 3 are giving same 4 binary input The same goes for the first two numbers of columns 2 and 4.
I'm confused I thought the encoder was suppose to output binary numbers from 0000 to 1111 where each key holds a respective binary representation. Please help me
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