AD8403 digital pot routine

[David Briscoe]

Hello all,
I am trying to put together the software to control an AD8403 digital pot for a filter project.I'm using a 16f628 or 16f877 PIC.
How would I modify the example included with the PCM compiler
(AD8400 included below) so that I can increment the Values of each of the 4 pots one at a time ( eg increment rdac1 to full resistance, then rdac2, then rdac3 annd so on).
Any help would be appreciated, thank you.
///////////////////////////////////////////////////////////////////////////
//// Library for a AD8400 ////
//// ////
//// init_pots (); Sets all of the pots to 0 ////
//// ////
//// set_pot (pot_num, new_value); Sets pot pot_num to new_value ////
//// ////
///////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,1997 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS C ////
//// compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, reproduction ////
//// or distribution is permitted without written permission. ////
//// Derivative programs created using this software in object code ////
//// form are not restricted in any way. ////
////////////////////////////////////////////////////////////////////////////

#define RST1 PIN_B0
#define CLK PIN_B1
#define DI PIN_B2
#define NUM_POTS 1

byte pots;

set_pot (int pot_num, int new_value)
{
byte i;
byte cmd[2];

pots = new_value;
cmd[0] = pots;
cmd[1] = 0;

for(i=1;i<=6;i++)
shift_left(cmd,2,0);

output_low(CLK);
output_low(RST1);

delay_us(2);
for(i=1;i<=10;++i)
{
output_bit(DI, shift_left(cmd,2,0));
delay_us(2);
output_high(CLK);
delay_us(2);
output_low(CLK);
delay_us(2);
}
output_high(RST1);
}

void init_pots ()
{
pots = 0;
}

Regards,
David Briscoe
London,England
___________________________
This message was ported from CCS's old forum
Original Post ID: 14204

[PCM programmer]

:=How would I modify the example included with the PCM compiler
:=(AD8400 included below) so that I can increment the Values of each of the 4 pots one at a time ( eg increment rdac1 to full resistance, then rdac2, then rdac3 annd so on).
:=Any help would be appreciated, thank you.
:=
:=#define RST1 PIN_B0
:=#define CLK PIN_B1
:=#define DI PIN_B2
:=#define NUM_POTS 1
:=
:=byte pots;
:=
:=set_pot (int pot_num, int new_value)
:= {
:= byte i;
:= byte cmd[2];
:=
:= pots = new_value;
:= cmd[0] = pots;


I think you can make it work with the AD8403 by
doing the following changes:
<PRE>
// cmd[1] = 0; // Comment this line out.
cmd[1] = pot_num; // Add this line
</PRE>

:=
:= for(i=1;i<=6;i++)
:= shift_left(cmd,2,0);
:=
:= output_low(CLK);
:= output_low(RST1);
:=
:= delay_us(2);
:= for(i=1;i<=10;++i)
:= {
:= output_bit(DI, shift_left(cmd,2,0));
:= delay_us(2);
:= output_high(CLK);
:= delay_us(2);
:= output_low(CLK);
:= delay_us(2);
:= }
:= output_high(RST1);
:= }
:=
:=void init_pots ()
:={
:= pots = 0;
:=}
___________________________
This message was ported from CCS's old forum
Original Post ID: 14217

[David Briscoe]

:=:=How would I modify the example included with the PCM compiler
:=:=(AD8400 included below) so that I can increment the Values of each of the 4 pots one at a time ( eg increment rdac1 to full resistance, then rdac2, then rdac3 annd so on).
:=:=Any help would be appreciated, thank you.
:=:=
:=:=#define RST1 PIN_B0
:=:=#define CLK PIN_B1
:=:=#define DI PIN_B2
:=:=#define NUM_POTS 1
:=:=
:=:=byte pots;
:=:=
:=:=set_pot (int pot_num, int new_value)
:=:= {
:=:= byte i;
:=:= byte cmd[2];
:=:=
:=:= pots = new_value;
:=:= cmd[0] = pots;
:=
:=
:=I think you can make it work with the AD8403 by
:=doing the following changes:
:=<PRE>
:=// cmd[1] = 0; // Comment this line out.
:=cmd[1] = pot_num; // Add this line
:=</PRE>
:=
:=:=
:=:= for(i=1;i<=6;i++)
:=:= shift_left(cmd,2,0);
:=:=
:=:= output_low(CLK);
:=:= output_low(RST1);
:=:=
:=:= delay_us(2);
:=:= for(i=1;i<=10;++i)
:=:= {
:=:= output_bit(DI, shift_left(cmd,2,0));
:=:= delay_us(2);
:=:= output_high(CLK);
:=:= delay_us(2);
:=:= output_low(CLK);
:=:= delay_us(2);
:=:= }
:=:= output_high(RST1);
:=:= }
:=:=
:=:=void init_pots ()
:=:={
:=:= pots = 0;
:=:=}
Thank you PCM programmer, I will try your suggestion.
Dave Briscoe.
___________________________
This message was ported from CCS's old forum
Original Post ID: 14251