Calculate with 16 bits value

[Walbeek]

Hi there,

I use a external ADC with 16 bit resolution to measure a voltage on the input.
The value is put in two byte´s, value-low and value-hi.
I would like to read the value from the ADC approx. 10 times a second.
After that I would like to calculate the average value of this 10 measurements.
Is it possible to use several values and calculate the average value fir these 16 bits again?
Can you please point me in the right direction.

Rinie

[Benj]

Hello Rinie,

First of all you can combine two 8-bit bytes into a 16-bit variable like this.

Code: Select all

Int = (Byte_MSB << 8) + Byte_LSB

This way you can store into 16-bit unsigned integer variables straight away.

You can then perform averaging by doing something like this.

Code: Select all

IntOld = Int
IntOldOld = IntOld
Int = ReadNewSample
Average = Int + IntOld + IntOldOld

This might get messy after say 3 iterations so moving to an array might help.

Code: Select all

//Cycle through array moving new to old
index = 1
numsamples = 10
while index < numsamples
{
 Int[index] = Int[index - 1]
 index = index + 1
}

//Collect latest 16-bit reading
Int[0] = ReadNewSample

//Perform average calculation
index = 0
average = 0
while index < numsamples
{
 average = average + Int[index]
 index = index + 1
}
average = average / numsamples

Hope this helps.