signed values for mini6410 ADC driver

Hi everyone,

      I get some values from ADC port.I cannot see values as negative.How
can I see negative values?

DO NOT APPLY NEGATIVE VOLTAGES TO THE ADC INPUT.

The ADC on the S3C6410 processor is not able to take negative voltages,
only positive and looking at the schematic and CPU documenation is
configured for 0-3.3V only.

If you want to read negative voltages you will need an external amplifier
to offset and scale the input to 0-3.3V and then do the conversion in
software.

For example, you can have a -10V to +10V input at the amplifier and this
outputs 0-3.3V to the ADC.

With the 10bit this would give you 1024 bits so 0-512 would be the negative
range and 513 to 1024 would be the positive range. Simple maths in software
will allow you to have -512 to +512 as the output.

Dave...

Thanks Dave,


   1. As a result of this I cannot draw sine graph or can I?

   2.If I cannot draw,how can I observe ECG signals ?

Hi Sinan,

What is the voltage output from the ECG?

You can draw a sine wave. You simply convert the 0-1204 reading to a -512
to +511 value.

Simple maths will do this for you.

Dave...

Thanks Dave I can draw sinus but now there is one more problem Clock ı
cannot get values for 100 Hz if I edit the clock register ı can solve
this problem ,am I right ?

I have no experience of the ADC so maybe someone else can help.