Bruno Thomsen

Unable to obtain MC9S08QE128 STOP3 mode datasheet current usage

Discussion created by Bruno Thomsen on Dec 10, 2007
Latest reply on Dec 28, 2007 by Ying-Ling Sun
I have been trying to put the MC9S08QE128 into STOP3 mode, but it still have a current usage of 21uA (datasheet: 450nA). I can get it into STOP2 mode with a current usage of 0.4uA (datasheet:350nA). The current measurement is done by putting a current meter in between the powersupply (3.1V) and VDD,VDD,VDDAD pins.

The init function is created using Device Initialization (DI) in CodeWarrior.

As reference I have used Application Note (AN3460) Low-Power Design Enabled by MC9S08QE128 and MCF51QE128 Flexis Microcontrollers.

The chip configuration:

Clock: internal oscillator 31.25kHz with FLL in bypassed low power and RTC uses a 1kHz low power oscillator.
Clock Gating: RTC and IRQ enable, all other disable.
GPIO: All pins are outputs without pullup resistors and logic low. The input only pin (port A pin 1) is used as IRQ1 with internal pullup resistor, with an external connection to a switch on the demo board (DEMOEQ).
The chip package on the demoboard is only 64 pins, but I am using the 80 pins layout in DI, so I can config all I/O ports.
Beans: Most beans have been initialized as disabled in the DI, but some require an input to init in the DI util (SPI1,SPI2,IIC1,IIC2,ACMP1.ACMP2). Those beans have been manually disabled in main().

RTC generate an interrupt each 5sec and toggle output number 1.
IRQ generate an interrupt when the switch is pushed and toggle output number 1.
Each main loop run toggle output number 2.

During current measurement the status LEDs on output number 1 and 2 are disconnected.
The two outputs toggle at the same time, so the MCU is not executing any instructions in the main loop after the stop instruction.

After loading the software onto the MCU, I push the IRQ switch to start it, since the debug software looses its input pin and are unable to start the code execution.

Any suggestions to what might help cut the extra 20uA of the current usage?

Best regards

Code attached.

Message Edited by t.dowe on 2009-10-27 01:28 PM