Low-power barebone Arduino problem


for my project I need a low-power unit. I oriented myself to the instruction on Gammon Forum : Electronics : Microprocessors : Power saving techniques for microprocessors
The uC cames from a burned Arduino Uno (touched accidentally one pin with 12V power-wire - the Arduino stops working after 5 minutes now - do not know what exactly is broken, but it is enought time to program the uC for the barebone :slight_smile: )

The active board consumes around 73mA, the following Sketch (“deep sleep”) 58mA!!! It is both 24mA more than an normal Uno!

Values from the page (active/asleep) in mA:
Uno 49/34
Barebone 15/0.4

Without the uC connected the multimeter shows 41uA (an ADXL345 is soldered directly to the barebone, so it should be ok)

Sketch B

#include <avr/sleep.h>

void setup () 
  set_sleep_mode (SLEEP_MODE_PWR_DOWN);  
  sleep_cpu ();  
}  // end of setup

void loop () { }

May the uC has taken damage despite that it works without any restriction? Or must the error be in the soldering?

How did you wire your barebone? Maybe it doesn't stay in sleep because it gets waked by an interrupt? Post the schematics (complete).

I have wired like this http://www.arduino-tutorial.de/wp-content/uploads/2010/06/bbArduino05.jpg but without reset-button and with external dc/dc (to 5V) converter. Sleep is working. I have measured active 73mA and asleep 58mA. 15mA is the usual save-value I think. Will post pictures soon.

EDIT: 10k resistor from reset to gnd is installed anyway.

EDIT2: resistor is connected to vcc not gnd

I have bought a new 328. With this one the barebone consumes (uC unprogrammed, without Arduinobootloader) about 8mA. But I do not get the bootloader installed. Seems that the broken Arduino is damaged to hard :-(

EDIT: 10k resistor from reset to gnd is installed anyway.

The 10k resistor should goto VCC not Gnd, check the schematics again, see your same image link again even in it the reset is to the vcc so how come you have wired it wrong?

Sorry, it is wired to vcc. I have looked wrong when I wrote this.

The lower level of current that you are trying to measure is either possible using a $600 Fluke or the Dave Jones uA current meter, Do you think your multimeter is that good?

also for example many multimeters like Vichy (many models of it!) are not upto mark with measuring stuff, so most probably if its a ELcheapo multimeter then dont waste your time trying to read uAmps out of it.

I know that. My goal is a low as possible standby-consumption. If the multimeter shows 70mA I know it is to much. If it shows 8mA I know that it is better. It does not matter how much it exactly is.

Are you measuring before or after the DC/DC converter?

After. The converter consumes 16mA without any load - it has to be replaced to reach the projects goal, but this is an other thing.

Please provide a wiring diagram that exactly matches your setup as your testing with.