[Contiki-developers] battery voltage

[mohamed ben hassen]

hi all,
i use contiki-2.4 and i 'd like to use the battery volatage
please ifs there any one know how can i show the level of the battery in my program ?
thanks a lot.

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[Marek Bykowski]

Hi All,

I join you Ben Hassen for the question. I'll need it particularity for the use in routing metrics to make it more energy efficient.

Thanks,
Marek

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[Carlo Alberto Boano]

Hi Mohammed,
I used to do the following, and it seems to work, but there might exist cleaner code.


int get_voltage() {
 SENSORS_ACTIVATE(battery_sensor);
 // Retrieving the voltage reference from the REF2_5V bit (1.5V or 2.5V) - I already multiply per 2
 int vref = 3;
 if((REF2_5V & ADC12CTL0) != 0) vref = 5;
 // Polling the ADC to get the battery voltage. I get an average of many values to be on the safe side
 unsigned long bsens = 0;
 int cnt = 0;
 for(cnt=0;cnt<20;cnt++) bsens += battery_sensor.value(0);
 bsens = bsens / cnt;
 // Converting the raw value to the actual battery voltage (mV) -  Value = raw_value / 4095 * Vref * 2
 unsigned long bs = (bsens * vref * 1000)/ 4095;  
 SENSORS_DEACTIVATE(battery_sensor);
 return (int) bs;
}

Hope it helps.

Best Regards,
Carlo Alberto Boano






mohamed ben hassen ha scritto:

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proactively, and fine-tune applications for parallel performance.
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[Marek Bykowski]

Actually is there a primitive to get the capacity value of the battery remained?

Marek

[mohamed ben hassen]

hi,Carlo
thank u for your help i test the function with hello world but i get some errors
i think that some librairies miss .am i right? please if u can help me don't esitate
i get these errors:
  [java] d.c: In function `get_voltage':
     [java] d.c:56: `Value' undeclared (first use in this function)
     [java] d.c:56: (Each undeclared identifier is reported only once
     [java] d.c:56: for each function it appears in.)
     [java] d.c:56: `raw_value' undeclared (first use in this function)
     [java] d.c:56: `Vref' undeclared (first use in this function)
     [java] d.c:57: syntax error before "unsigned"
     [java] d.c:59: `bs' undeclared (first use in this function)
     [java] d.c: In function `process_thread_hello_world_process':
     [java] d.c:71: warning: implicit declaration of function `et_voltage'
     [java] make: *** [d.co] Erreur 1
     [java] Process returned error code 2
     [java]
thanks a lot,
Mohamed

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[Borms Joris]

Actually, there is.

 

“lib/sensors.h” and “dev/battery-sensor.h” define the API for the battery sensor. The implementation depends on the platform of course – you’ll find it in “platform/(platform name)/dev/battery-sensor.c” if it exists.

 

Basically,  you activate the battery sensor with battery_sensor.activate() and you can get its value with battery_sensor.value(0). You will probably need to rescale the result of that operation to a desired magnitude though.

 

Joris

[Borms Joris]

Whoops, mixing old and new API, as you can see from Carlo's code, you activate the sensor with SENSORS_ACTIVATE(battery_sensor).

You may not need the averaging, but his code is pretty close to the simplest way to read battery voltage. You could also leave the "sensor" activated, instead of deactivating it at each get_voltage().

Van: Borms Joris [mailto:jbo...@etro.vub.ac.be]
Verzonden: Thursday, April 15, 2010 1:45 PM
Aan: Contiki developer mailing list
Onderwerp: Re: [Contiki-developers] battery voltage

Actually, there is.

"lib/sensors.h" and "dev/battery-sensor.h" define the API for the battery sensor. The implementation depends on the platform of course - you'll find it in "platform/(platform name)/dev/battery-sensor.c" if it exists.

Joris

Hope it helps.

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[Carlo Alberto Boano]

Hi,
I agree with you Joris.
The only thing with the deactivation is that the ADC configuration might
collide with the one needed for other purposes.
So I deactivated it to be on the safe side (I was retrieving the
temperature from the MSP, and this requires another configuration).

Best Regards,
Carlo Alberto Boano

Borms Joris ha scritto:

[hamma hamma]

hi all , sorry for this stupid question
i need to know the voltage of each node and i use the sky platform
i saw the code in the archive but i don't understand how can i get the value
i test the code of carlo but it seems that there is a lot of errors.
please can any one guide me step by step
 best regards,

[Borms Joris]

The line "Value = raw_value / 4095 * Vref * 2" is a comment describing the rescaling of the raw value measured with the ADC to a more meaningful value. If you leave it in comment the code should compile fine. For more details, check the datasheet of the MSP430 microcontroller, specifically the section that describes the ADC12.

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[Carlo Alberto Boano]

Hi,
I forgot to mention that the function I pasted before takes many samples
from the ADC, performs an average, and converts the raw value to
millivolts.
So, it returns the mV as integer. It compiles fine for me, and it looks
like it work fine, I hope it does for you as well. Remember to add
#include "dev/battery-sensor.h".

Best Regards,
Carlo Alberto Boano

Borms Joris ha scritto:

[hamma hamma]

hi,Boms Joris
thank u a lot now i understand the  procedure. but i have a small question the voltage that i get {53 mv ,164mv }all the values under 1v
is that right because the battery initially ist about 1.5 or 2.5 v but the values that i get decrease  very quickly.normally i must get some value in volt ?
the value that i get is the current volatge of the battery?
best regards,
hamma

[Renato Spiandorello]

Hi, please do you remeber any issue in Contiki 2.3 related to more than 1 icmp reply of empty ?

 

thank you in advance

 

greatings

 

rs