Andre,
please try this example in C (CCS compiler):

long int average_sensor;            //   filtered values    (13 bits)
long int vsensor;                       //   sensor readings  (13 bits)


void read_sensor ()
{
   set_adc_channel(2);
   delay_us(10);
   vsensor = read_ADC();
}


void filter()
{
   static long int acumulator;

   acumulator = acumulator - (acumulator >> 3) + vsensor;
   average_sensor = acumulador >> 3;
}



main()
{
    read_sensor();
    filter();
}



Best regards,
Fabricio.




----- Original Message ----- 
From: "Andre Abelian" <aabelian@mason-electric.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, June 19, 2007 5:52 PM
Subject: RE: [pic:] Software low pass filter any idea?


> Fabricio,
>
> thanks for your help.
> since I use 2 bytes (13 bit) I will go with 13 or 16 bits.
>
> thanks
>
> Andre
>
>
>
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Marcos Fabricio Bezerra
> Sent: Tuesday, June 19, 2007 12:12 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [pic:] Software low pass filter any idea?
>
>
> Hi, Andre.
> I advice you to use a digital implementation of an IIR filter.
> How many bits do you really need?
> Fabricio.
>
>
>
> ----- Original Message ----- 
> From: "Andre Abelian" <aabelian@mason-electric.com>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Tuesday, June 19, 2007 3:36 PM
> Subject: [pic:] Software low pass filter any idea?
>
>
>> Hi to all,
>>
>> I am using external 13 bit ADC witch originally won't necessary
>> to go that high resolution "not under my control" now the result
>> I am getting is noisy numbers are going high and low. what I did is
>> reading it 10 times then I add them together then divide it by 10.
>> It helps but one of our engineer asked me to add software low pass
>> filter witch I am familiar with it. Reading 10 times values are up to 15
>> point
>> different.
>> My question is do you have any experience or know how software LPF work?
>> any link or info will appreciate. I searched piclist.com not enough info
>> I found to understand what to do.
>>
>> thank you for your help
>>
>> Andre
>>
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