AnsweredAssumed Answered

STM32F103 Matrix Keypad is causing CPU Halt

Question asked by aslan.selahattin on Nov 2, 2015
Latest reply on Nov 2, 2015 by Clive One
Hi
I'm using STM32F103 in our products. We have sold about 700 unit before.
Now We are in second mass production.

But we have faced with a problem that has been reported by the clients.

Our device features are:
- RFID based door access controller
- 4x4 membrane matrix kaypad
- 10/100 Ethernet interface with a co-ethernet cpu (Wiznet W5200)
- 3.3V and 5V supply available on board
- 2x16 digits character LCD
- RS-232 and RS485 interface
- 2 Relays


The problem is ;
When a user try to use keypad, the device is stopping to run.
In this case,
- Keypad is not working
- Blink LEDs are stopping
- TCPIP is off

The periode of this failure is different from device to device. 1 hour, 1 day or 2 days.

We have tested here. We saw this problem in our R&D

I have added serial resistor (470R) to matrix keypad outputs.
And We used 100nF capacitor (to ground) in the keypad inputs.

The problem is solved mostly. But after 1 week, We saw the failure again.

What can we make more to solve this failure completely

Selahattin Aslan

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