ASCII readings: how to onvert the values - Logomatic 2

Development Boards MicroMod
1

Hello,

I got readings of around 50 for a voltage of around 170mV. How can I convert these values, is there any formula, its not Hex to Decimal.

Cheers,

Steffen

2

Steffen,

Is that 50 decimal or 0x50 hex?

Either way, you can determine what your ‘step size’ is per lsb of the ADC by converting to decimal (50=50 or 0x50=80) and dividing your known voltage by this:

170mV/50lsb = 3.4 mv/lsb

or

170mV/80lsb = 2.125 mv/lsb

If you want to do this from the datasheet without guessing you need to look at the schematic, and the data sheet of your processor/ADC and determine

  1. the reference levels supplied to the ADC (probably 3.3v)

  2. the number of bits in your ADC (10-12 in the case of dspics, no idea for arms)

Then, take your reference range of 3.3v-0v=3.3v, and divide it by the number of levels your ADC has (2^n bits -1, → 2^10 -1=1023)

3.3/1023 = 3.23 mV/ code → This matches pretty well with case 1 above.

good luck Steffen.

3

thanks Cannibal,

its decimal.

Got it, yes, say 171:3.3V = 53:1024.

So that is solved, now it should be fine, the other 2 things are in this forum already, hope I get it to work (1 reading per 60s and time stamp)

Cheers,

Steffen