topic Re: issue with mux'd pins in Kinetis Microcontrollers

issue with mux'd pins

vinkar — Wed, 02 Jul 2014 08:55:29 GMT

Hello,

I am using the KL04 chip (24 pins package).

I want to use the comparator module in this chip(pins 13,19,20 and 22).

Assuming I give the reference ('-') input to the pin 22 (so its a step down of a supply of 11V to a

KL04 compatible 3.3V.

But, this is muxed to SWD_CLK programming pin. This would mean that there might be an issue

with programming and/or debugging. How can this be solved. I am using the Multilink Universal from PE.

Vinod.

Re: issue with mux'd pins

mjbcswitzerland — Wed, 02 Jul 2014 19:50:59 GMT

Vinod

The default pin function is SWD CLK out of reset. If you ensure that the analoge signal can be removed when debugging (so that the clock from the debugger is not disturbed) you will be able to program and debug on the port.

It will however not be possible to test the cmparator input operation when the debugger is attached.

The application needs to change the pin function for it to become a comparator input so it may be advisable to make the code detect when you are debugging (eg. set the state of a spare input to signal that you want to retain debugging functionality) and not reprogram the pin so that the debugger can continue to operate when debugging other parts of the code.

Regards

Mark

Re: issue with mux'd pins

galadragos — Thu, 03 Jul 2014 18:47:03 GMT

See if you can connect the - signal to another pin.

If you disable the SWD_CLK then you won't be able to do any debugging. Further more, it will be tricky to program the chip.