Hi,
I am using a 4 key keypad in my design where the microcontroller is PIC24FXXX. I have been using matrix keypads since more than a decade, however this time I have come across a noise problem in keypad. Before describing the problem I must tell that here is a 1K pull down already on key pad inputs, the scan rate s 20HZ and keypad debouce has been taken care of in firmware.
Coming to the problem, this system has a motor and VFD installed in a box with my board also in it. the key pad is connected via cable with 18 inch wire. My MCU is reading ghost input signals from keypad while system is running, I am not able to understand how to take care of such noise.
Please help
Anshuman
I am using a 4 key keypad in my design where the microcontroller is PIC24FXXX. I have been using matrix keypads since more than a decade, however this time I have come across a noise problem in keypad. Before describing the problem I must tell that here is a 1K pull down already on key pad inputs, the scan rate s 20HZ and keypad debouce has been taken care of in firmware.
Coming to the problem, this system has a motor and VFD installed in a box with my board also in it. the key pad is connected via cable with 18 inch wire. My MCU is reading ghost input signals from keypad while system is running, I am not able to understand how to take care of such noise.
Please help
Anshuman