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AT90S8535 - putting micro into power down mode and waking it

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nzkunal

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at90s8535 rojo

Hi
I am using an AT90S8535. I wanted to know if anyone had any ideas on powering the micro down I know there is an inbuilt powerdown function but I am not sure how to use it. At the moment I have connected a push button to external interrupt 1 and want to use that to toggle the micro from ON/OFF mode. Any ideas?
 

rojo

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Re: AT90S8535 - putting micro into power down mode and wakin

yeah, www.atmel.com ;))
 

panalog9

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Have you read the datasheet ? It's quite detailed, and gives good information about using the external interrupts, and the various power-saving modes.

While the system is running, configure INT1 to be edge-sensitive, and have your interrupt routine handle debouncing if necessary. Set a global flag to indicate POWER_DOWN_NOW. The mainline code sees this flag in the main loop, sets INT1 to be level sensitive, and puts the micro to sleep.

It has to be level sensitive to be used for wakeup. Now when a push happens, the micro wakes up, and ints to INT1 routine.

Read the datasheet.

-pana
 

vssumesh

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Hi Pana,
I am new to this group and i am not sure whether you people are still watching this.
I have figured this out on 89S52 after long experiments(it is not mentioned in the 89S52 data sheet atleast). I have figured out the solutions but dont know the reasons. Could you please answer to my following querries.
1. Why is that the recovery from power down mode to be level triggered? Is this a bug ? (Atmel FAE doesnt have a clue but in the end he admitted that it is not present in the data sheet. Actually it is present :) but very slightly mentioned in a section detailing WDT).
2. Why cant we enter the power down from an ISR. Whenever i attempted it the system hang. And later after lot of trial and error i used a global variable as you suggested. But why cant simply enter and exit from power down mode from any part of the code?

Also please let me know any solution to the following issue.
My system is picking up electrical noise while in power down mode. I am using filter capacitors but still it will wake up from the power down mode whenever i switch on/off any electrical appliance. I am using linear regulator using LM317. Will switching to the SMPS like MC34063 improves the situation? Since the interrupt is level triggered (The power down mode will be recovered only after removing the interrupt) i am not able to check the interrupt pin for any noise. Please advise.
One more thing is that my system is picking up electrical noise only when it is in power down mode.
 

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