STM CircleOS forum / Incorrect battery voltage for Primer1

neogir · 2010-01-24 11:58:22

Primer1. OS 3.8
In Config/Test BAT=1.24V. When R35 is shortened, BAT=2.47, so I may guess you have forgot about R35:R14 in OS code (sorry if it is documented anywhere but I missed).

Also, it seems the charging level is always shown as 100%. Regardless to the real bat state.

yrt · 2010-01-25 08:01:47

What is the real voltage (measured) of your battery ?

neogir · 2010-01-25 08:24:53

About 2.5V when Primer is on. Some dozen mV more when off. Internal Test shows half of the real voltage. In correspondence with the ADC pin27 input voltage from R35:R14.

yrt · 2010-01-26 10:12:27

Hi,

What is the version of your pcb Primer, and what resitor values do you have (R35 and R4) ?

neogir · 2010-01-26 11:16:53

Sorry, i misprinted, of course, R35:R4.
PCB v1.2. Both resistors are 1M (as printed on them 10^5). But in this case it is not matter though.
While meausuring by multimeter (ground at J3.1, ADC voltage at common point of R35:R4 or pin U1.27 ), voltage is 0.86V (due to multimeter resistance of some MOhms), both multimeter and Primer show the correct value of 0.86V. If R35 is shortened, ADC starts to display the correct battery voltage .

yrt · 2010-01-26 12:56:39

You're right.
It's seems that there is a display bug from the beginning, but not present on Primer2 !
Sorry.

neogir · 2010-01-26 17:26:59

I am not so interested in Circle OS, but just have had a look into the OS source code.

...

vbat = 0;
for ( i = 0; i < ADC_NB_SAMPLES; i++)
{
vbat += ADC_ConvertedValue[0 + i*ADC_NB_CHANNELS];
}
vbat = vbat / ADC_NB_SAMPLES;

vbat = vbat & 0xFFF;
vbat = ( vbat * VDD_VOLTAGE_MV ) / 0x1000;

#ifdef PRIMER2
vbat *= 2; //Divider bridge Vbat <-> 1M -<--|-->- 1M <-> Gnd,
#endif

...

So, I may guess some previous versions of Primer1 do not have the R35:R4 divider, and for my Primer1 code line

vbat *= 2;

should be free of any #ifdef condition at compile time.

yrt · 2010-01-27 08:09:44

Be careful, the vbat data is used at several places (main page display, battery presence detection...).

neogir · 2010-01-27 09:35:49

I'll do my best
Have bought Primer1 just to investigate Cortex-M3 and peripherals, f.e. 3D accelerometer. Personally I'm interested in ARMv7 assembler language, so do know what does "be carefull" mean. Very soon your nice device will be modified, upsoldered, and so on. May be it ends up too soon, in my hands.

# 1 2010-01-24 11:58:22 Incorrect battery voltage for Primer1

Incorrect battery voltage for Primer1

# 2 2010-01-25 08:01:47 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 3 2010-01-25 08:24:53 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 4 2010-01-26 10:12:27 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 5 2010-01-26 11:16:53 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 6 2010-01-26 12:56:39 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 7 2010-01-26 17:26:59 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 8 2010-01-27 08:09:44 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

# 9 2010-01-27 09:35:49 Incorrect battery voltage for Primer1

Re: Incorrect battery voltage for Primer1

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