MC13224 and Low Power Mode

[Houarcheneger]

Hi everybody

I encountered a problem with MC13224 integrated on a board.

All was OK (RF, UART communication...) since the board turned off (the LED controled by the micro switched of). I checked power supplies. I then tried to reload the program into the micro but I got two types of error message :

"TCK (pin 9) low, but should be high. Please check target hardware" and "target VCC failure. Please check target voltage. Could not find supported CPU core on JTAG chain"

&

"Could not find supported CPU core on JTAG chain
Bad Jtag communication: Write to IR: Expected 0x1, got 0x0 (TAP Command : 2)
@ Off 0x5.
Unable to halt ARM core"

I sent an email to technical support. I have been told that the micro might be in Low Power Mode. I read the datasheet to get information about this mode and I learnt that there are only software ways to entry this mode: DOZE or HIB bits in SLEEP_SYNC should be set. I checked and they are both to zero. Thus, I am not really sure the micro is in Low Power Mode. Maybe another way exist (?)

Furthermore, this problem appeared on several boards but not on all. I then compared crystal signals from a safe board and from the dead one. These signals are the same.

Does someone can help me ? Many thanks.

Houarcheneger.

[AmitPatil]

Hi Houarcheneger,

When you try to flash a new solution on your device that already has a Low Power Mode code in it, it becomes difficult for IDE to halt the CPU (frequency mismatch) and add new code to it.  So make sure you have a device turned off until you initiate flashing process.  Turn on the device the very moment your flashing process is about to start. This way device does not get chance to go in LPM and IDE can halt the CPU.  I know it's wierd but we have to live with it.

Looking at your problem, I thought you might have faced or about to face few problems like these so wrote them as well.

"Can not halt CPU" error when I did Download and Debug?

When you go for "download and debug" of a project that has Low Power Mode enabled, this problem may occur.  This happens because when device goes in to low power mode, it changes it's working frequency. (moves to ring oscillator or ext. oscillator as per settings.)  The debugger can not handle this and gives the errors.  So that means, you can not debug a device which can go in Low Power Mode.

It crashed while debugging and now it's not allowing me to flash again?

Some times IDE crashes badly and doesn't even let to build or flash device from IDE after this .  In this case you can close entire workspace and open it again.  I know it's a wierd solution (but hey it's the problem as well ), but it worked for me.

[sharning]

A handy thing to do when using low power mode is to put a 3 second delay loop in the start of Main(). This allows sufficient time after reset to download new firmware before you program ever gets a chance of entering a low power state.

I also agree about having to restart IAR after it crashes - sometimes you can just unplug and re plug in the J-Link debugger.