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High current in powerdown mode. Why?

 
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hg7kaz

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Joined: 15 Aug 2007
Posts: 6

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PostPosted: Fri Feb 06, 2015 11:49 am    Post subject: High current in powerdown mode. Why? Reply with quote

Hello!

I built a simple circuit. The processor is an Atmega328P, internal 8MHz oscillator divided by 8. An CR2032 Li battery gives the supply voltage.
I want to try the power reduction and the powerdown mode with a battery.

The code is:

Code:

$regfile = "m328pdef.dat"
$crystal = 1000000

$hwstack = 32
$swstack = 16
$framesize = 24

wait 3       ' I = 3,08mA

' -----------------------------------

' Switch OFF the Analog Comparator

set acsr.acd
set didr1.ain1d
set didr1.ain0d

' Switch OFF the Voltage Reference

reset admux.refs1
reset admux.refs0

' Switch OFF the ADC

reset adcsra.aden

' Switch OFF all blocks

PRR = &B111101111

' -----------------------------------

wait 3 '            I = 2,88mA -> it's too high!

' -----------------------------------

Config Powermode = powerdown


' I = 2,33mA
'much smaller current uptake was written at this in the data sheet Sad(((

End
 


When the processor is in the powerdown mode, the current for much smaller one should be at it what I measured.

Is something missing from the program?
Thank you for the help!

(BASCOM-AVR version : 2.0.7.8 )
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MWS

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Joined: 22 Aug 2009
Posts: 1801

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PostPosted: Fri Feb 06, 2015 1:29 pm    Post subject: Reply with quote

The code is ok, it does what it should.
Power consumption for powerdown is too high, which is likely a hardware issue. How the current is measured, with or without connected ISP?
A schema would help.

One soft-issue is thinkable, in case the WDTON-fuse is programmed. Then the watchdog-reset repeatedly calls the C from sleep.
This can be fixed by un-programming the WDTON fuse.
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hg7kaz

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Joined: 15 Aug 2007
Posts: 6

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PostPosted: Fri Feb 06, 2015 2:06 pm    Post subject: Reply with quote

MWS wrote:
The code is ok, it does what it should.
Power consumption for powerdown is too high, which is likely a hardware issue. How the current is measured, with or without connected ISP?
A schema would help.

One soft-issue is thinkable, in case the WDTON-fuse is programmed. Then the watchdog-reset repeatedly calls the C from sleep.
This can be fixed by un-programming the WDTON fuse.


I want to use the watchdog later.
I disconnect the ISP always after programming the code.

The circuit is very-very simple: 2x3 pin header for the ISP, two decoupling capacitor (100n on the reset and VCC pins), the battery holder, the 328p, and an unused led with resistor for test. The +3V connected the VCC, and AVCC+AREF pins and the reset pin via pull-up resistor (4,7k).
The meters:
- digital Uni-T UT71C,
- analog Tesla BM-518.

I tried out an other electronic circuit meanwhile, the one in which there is an Atxmega256A3U, but I measured high value there again in powerdown mode (~500uA).
I checked both instruments, they are properly.
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MWS

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Joined: 22 Aug 2009
Posts: 1801

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PostPosted: Fri Feb 06, 2015 2:52 pm    Post subject: Reply with quote

hg7kaz wrote:
I want to use the watchdog later.

That's fine, but does this actually say, that the watchdog fuse is un-programmed = 1 by now?
Quote:
an unused led with resistor for test.

You do not enable any ports or pullups, so this is no issue.
I would enable the led, blink for 1 second and disable it then, this shows you cyclic resets.
Quote:
The +3V connected the VCC, and AVCC+AREF pins and the reset pin via pull-up resistor (4,7k).

How about brown out?
Show pictures of your circuit and a screen shot of the fuses, as said, the code is ok,
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hg7kaz

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Joined: 15 Aug 2007
Posts: 6

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PostPosted: Fri Feb 06, 2015 3:10 pm    Post subject: Reply with quote

MWS wrote:
the code is ok,


Quiet strange, that works rewriting the program perfectly on a M1284P, which is just like this in a simple circuit, yes. The current was 130nA! The DMM can't measure it, only the Tesla laboratory meter. Laughing

It occurred already early that there was a mistake in a Bascom version, something similar happened now possibly.
I revise the pcb thoroughly whatever, something escaped my attention maybe.
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MWS

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PostPosted: Fri Feb 06, 2015 3:21 pm    Post subject: Reply with quote

hg7kaz wrote:
It occurred already early that there was a mistake in a Bascom version, something similar happened now possibly.

I've checked the created code on ASM level, it shows to be ok.
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hg7kaz

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Joined: 15 Aug 2007
Posts: 6

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PostPosted: Fri Feb 06, 2015 3:30 pm    Post subject: Reply with quote

MWS wrote:
hg7kaz wrote:
It occurred already early that there was a mistake in a Bascom version, something similar happened now possibly.

I've checked the created code on ASM level, it shows to be ok.


Thank You!
The error will be on the panel then. I hope.
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Evert :-)

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Joined: 18 Feb 2005
Posts: 2107

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PostPosted: Thu Feb 12, 2015 8:29 pm    Post subject: Reply with quote

Disable the BOD fuse, is drains much power.

Some more tips;
Code:

'=== Setup for low power mode ===
Config Portb = Input                                        'to Reduce Power , Setup All Pins As Inputs With No Pullups
Config Portd = Input
Config Portc = Input

Adcsra.aden = 0                                             'Disable a/d convertor
Acsr.acd = 1                                                'Disabel analog comperator
Didr0 = &H3F                                                'Disable digital input buffers on all ADC0-ADC5 pins
Didr1.ain0d = 1                                             'Disable digital input buffer on AIN1/0
Didr1.ain1d = 1

Config Adc = Single , Prescaler = Auto , Reference = Internal_1.1
Stop Adc

Prr.pradc = 1                                               'Power adc disable
Prr.prspi = 0                                               'Power spi disable
Prr.prtim0 = 1                                              'Power timer0 disable
Prr.prtim1 = 1                                              'Power timer1 disable
Prr.prtwi = 0                                               'Power twi
Prr.prusart0 = 0                                            'Power Usart0

 


Nice tutorial https://www.sparkfun.com/tutorials/309

You don't have a main loop, try this:
Code:

do
Config Powermode = powerdown
loop
End
 

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Last edited by Evert :-) on Fri Feb 13, 2015 12:03 am; edited 2 times in total
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MWS

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Joined: 22 Aug 2009
Posts: 1801

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PostPosted: Thu Feb 12, 2015 9:00 pm    Post subject: Reply with quote

Evert Smile wrote:
Disable the BOD fuse, is drains much power.

According data sheet at 3V/25 the brownout takes 18A. You consider that as "much power"?
The TO's issue is much different:
Quote:
I = 2,33mA

Considered that, 18A is in the range of measurement uncertainty.
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Evert :-)

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PostPosted: Thu Feb 12, 2015 9:12 pm    Post subject: Reply with quote

if you want the poweruse back to 1,5A then 18A is MUCH.
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MWS

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PostPosted: Thu Feb 12, 2015 10:42 pm    Post subject: Reply with quote

Evert Smile wrote:
if you want the poweruse back to 1,5A then 18A is MUCH.

The TO looks for a whooping 2330A and if BOD should be "much" in this context, I simply would expect a bit more than these few A's.
In other words: what sense does it make to suggest the use of better streamlined wipers, if the car has to pull against an activated hand brake?
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AdrianJ

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PostPosted: Fri Feb 13, 2015 12:40 am    Post subject: Reply with quote

I have had 100nF bypass caps go leaky and pass several mA, also very temperature dependent.
Suggest try removing them and measure the current.

Better is to take a fresh board, install everything EXCEPT the processor and measure the current. Then install the processor and see the change. That way you know the board itself is not the problem.

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