MCF51QE128 - Issue on waking up from Stop3 mode

[stephen_IT]

Hello all,

I'm experiencing a big trouble with MCF51QE128 configuring low power mode in a battery supplied device.

The MCU is supposed to get into Stop3 mode by "_Stop" call; and it's supposed to wake up every 1 second on RTC interrupt. Well, it wakes up for just 32seconds (always 32 seconds!) and then it gets stuck (no wake up for any reason) with costant power consuption (about 20 micro Amps).

MCU configuration:

- RTC clocked by external Osc 32.768 KHz

- MCU clocked by FLL (32.768 Khz x 1024 = 33.554 MHz).

- SPMSC2_LPR = 1;

- SPMSC2_LPWUI = 1;

- On Stop call:

  SPMSC1_LVDSE = 0;  // required to activate Stop3 Mode

  _Stop;

  SPMSC2_LPR = 1;

  SPMSC1_LVDSE = 1;

Can anyone help me?

Thanks in advance

Stephen

[leopard86]

Old post but I'll give an answer to help out people:

If using stop modes RTC must use the internal LPO 1KHz oscillator, no external clocks! Otherwise RTC will get no clock signal and won't be able to raise any interrupt.

bYE