wiring_analog.c

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#include <Arduino.h>
 
static const int Ctrduty = 6;
static const int Dutyperiod = 0x1010101;
 
// Assume Propeller ASC for analogRead for now.
// Note the code below is an Arduino-fied version of code given
// to me by Michael Swartzendruber in the Parallax forum.
 
#define      SE_0    0x08              // ch0  single ended
#define      SE_1    0x09
#define      SE_2    0x0A
#define      SE_3    0x0B
#define      SE_4    0x0C
#define      SE_5    0x0D
#define      SE_6    0x0E
#define      SE_7    0x0F
 
#define      D_01    0x00             // 0+/1-  differential
#define      D_10    0x01             // 1+/0-
#define      D_23    0x02             // 2+/3-
#define      D_32    0x03             // 3+/2-
#define      D_45    0x04             // 4+/5-
#define      D_54    0x05             // 5+/4-
#define      D_67    0x06             // 6+/7-
#define      D_76    0x07             // 7+/6-
 
static const int adcChannel2SE[8] = {SE_0, SE_1, SE_2, SE_3, SE_4, SE_5, SE_6, SE_7};
static const int clockDelay = 400;
 
// pins for the Propeller ASC A/D convertor.
volatile int  cs;
volatile int  clk;
volatile int  dio;
 
void init( int cspin, int clkpin, int diopin )
{
  cs  = cspin;
  clk = clkpin;
  dio = diopin;
 
  pinMode( cspin, OUTPUT );
  digitalWrite( cspin, HIGH );
 
  pinMode( clkpin, OUTPUT );
  digitalWrite( clkpin, LOW );
}
 
void finalize()
{
  pinMode( cs, INPUT );
  pinMode( clk, INPUT );
  pinMode( dio, INPUT );
}
 
int do_adc_cmd( int mux )
{
  int level = 0;
  int counter;
 
  // Read MCP3208 channel
  // -- mux is encoded mux bits for channel/mode
 
  digitalWrite( cs, LOW );                                      // activate adc
  pinMode( dio, OUTPUT );                                       // dio is output
 
  // output mux bits, MSBFIRST
 
  for ( counter = 0; counter < 5; counter++ )
  { // send mux bits
    digitalWrite(dio, (mux & 0x10) ? HIGH : LOW);
    delayMicroseconds( clockDelay );
    mux <<= 1;
    digitalWrite( clk, HIGH );                                  // clock the bit
    delayMicroseconds( clockDelay );
    digitalWrite( clk, LOW );
  }
 
  // input data bits, MSBPOST
 
  pinMode( dio, INPUT );                                        // dio is input
 
  level = 0;                                                    // clear work var
 
  for ( counter = 0; counter < 13; counter++ )
  { // null + 12 data bits
    digitalWrite( clk, HIGH );                                  // clock the bit
    delayMicroseconds( clockDelay );
    digitalWrite( clk, LOW );
    delayMicroseconds( clockDelay );
    level = ( level << 1 ) | digitalRead( dio );                // input data bit
  }
 
  digitalWrite( cs, HIGH );                                     // de-activate adc
 
  return( level & 0x0fff );
}
 
// -- ch is channel, 0 to 7
// -- mode is 0 for single-ended, 1 for differential
int read_adc_channel( int ch_mode )
{
  long adc_cmd;
 
  adc_cmd = 0x10 | ch_mode ;  // create mux bits
 
  return do_adc_cmd( adc_cmd );
}
 
int analogRead(uint8_t adcChannel)
{
  init( 27, 25, 26 );
  int value = read_adc_channel(adcChannel2SE[adcChannel]);
 
  value = map(value, 0, 4095, 0, 1023);
 
  return value;
}
 
void analogReference(uint8_t mode)
{
}
 
void analogWrite(uint8_t pin, int duty)
{
  CTRA = 0;
  FRQA = (Dutyperiod * duty);
  CTRA = ((Ctrduty << 26) + pin);
}