example_2_dc.c

CYGNAL单片机

//-----------------------------------------------------------------------------
// Example 2
// DC Motor Control with Reversing
//-----------------------------------------------------------------------------
// Copyright 2004 Silicon Laboratories Inc.
//
// AUTH: KAB
// DATE: 12MAR04
//
// This program provides DC motor control with hard reversing using the PCA
// 8-bit PWM Mode. A single PCA module is used to generate an 8-bit PWM. The
// pin skip register XBR0 is used to multiplex the PWM between two outputs
// P0.0 and P0.1. These two outputs are used to drive the lower transistors in
// an H-Bridge configuration. P0.2 and P0.3 are used to drive the upper
// transistors.
//
// The ADC is used to read the poteniometer voltage on P0.6. The ADC uses polled
// mode and 64 sample averaging.
//
// When the pushbutton is pressed and held the PWM duty cycle will be set to
// zero and all transistors will be turned off. This will allow the motor to
// coast. Releasing the switch will cause the motor to reverse. If the switch
// is released before the motor comes to a complete stop, the motor will
// abruptly stop and reverse directions.
//
// Target: C8051F30x
//
// Tool chain: KEIL Eval 'c'
//
//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f300.h>                 // SFR declarations

//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------
void SYSCLK_Init (void);               // Initialize SYSCLK
void PORT_Init (void);                 // Initialize XBR and Port Pins
void PCA0_Init (void);                 // Initialize PCA0
void ADC0_Init (void);                 // Initialize ADC
unsigned char readVin(void);           // read ADC using polling
unsigned char avgVin(void);            // returns avg ADC reading
void coast (void);
void reverse (void);
//-----------------------------------------------------------------------------
// Global Variables
//-----------------------------------------------------------------------------
bit Fwd;
sbit SW1 = P0^5;
//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------
void main (void)
{

   PCA0MD &= ~0x40;                    // Disable Watchdog Timer

   SYSCLK_Init ();                     // Initialize system clock
   PORT_Init ();                       // Initialize crossbar and GPIO
   ADC0_Init();                        // Initialize ADC for polled mode
   PCA0_Init ();                       // PCA0 for 8-bit PWM
   Fwd = 1;                            // start in forward direction
   EA = 1;                             // enable global interrupts

   while (1)
   {
      if(SW1)                          // if not pressed
      {

         PCA0CPH0 = avgVin();          // get avg reading and output to PWM
      }
      else
      {
         coast();                      // if pressed, coast
         while(!SW1);                  // wait for button to be released
         reverse();                    // reverse directions
      }
   }
}

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clock to use the internal 24.5MHz
// oscillator as its clock source.  Also enables missing clock detector reset
// and the VDD Monitor.
//
void SYSCLK_Init (void)
{
   OSCICN = 0x07;                      // Configure internal oscillator for
                                       // highest frequency.
   RSTSRC = 0x06;                      // Enable missing clock detector
                                       // and VDD Monitor.
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports.
// P0.0 - /Abot - active low PWM signal drives bottom transistor
// P0.1 - /Bbot - active low PWM signal drives bottom transistor
// P0.2 - /Atop - active low signal drives top transistor
// P0.3 - /Abot - active low signal drives top transistor
// P0.4 -
// P0.5 - Switch
// P0.6 - Vin
// P0.7 -
//
void PORT_Init (void)
{
   XBR0    = ~0x01;                    // skip all except P0.0
   XBR1    =  0x40;                    // Enable CEX0 on P0.0
   P0MDOUT =  0x0f;                    // P0.0 - P0.3 are push-pull outputs
   P0MDIN  = ~0x40;                    // Configure P0.6 for analog input
   P0      = ~0x08;                    // P0.3 low
   XBR2   |=  0x40;                    // Enable crossbar
}


//-----------------------------------------------------------------------------
// PCA0_Init
//-----------------------------------------------------------------------------
//
//
void PCA0_Init (void)
{

   PCA0MD = 0x02;                      // PCA uses sysclk/4, no interrupt

   PCA0CPM0 = 0x42;                    // Module 0, 8-bit PWM Mode

   PCA0L = 0x00;                       // reset the timer
   PCA0H = 0x00;
   PCA0CPL0 = 0x00;                    // Initialize to minimum duty
   PCA0CPH0 = 0x00;
   CR = 1;                             // Start PCA0 timer

}

//-----------------------------------------------------------------------------
// ADC0_Init
//-----------------------------------------------------------------------------

void ADC0_Init (void)
{
   ADC0CN = 0x40;                      // Low-power tracking mode;
                                       // ADC0 conversions are initiated
                                       // on writes to AD0BUSY;
   AMX0SL = 0xf6;                      // select P0.6, single-ended
   ADC0CF = 0x81;                      // AD0SC=4 gain =1
   REF0CN = 0x0a;                      // ADC uses Vdd for full scale
   EIE1 &= ~0x04;                      // disable ADC0 EOC interrupt
   AD0EN = 1;                          // enable ADC
}

unsigned char readVin(void)
{
   AD0INT = 0;                         // clear ADC0 end-of-conversion
   AD0BUSY = 1;                        // initiate conversion
   while (!AD0INT);                    // wait for conversion to complete
   return ADC0;
}


unsigned char avgVin(void)
{
   unsigned char i, result;
   unsigned int sum;

   sum = 0;
   for (i = 64; i != 0; i--)           // repeat 64 times
   {
      sum += readVin();                // read ADC and add to sum
   }
   result = (unsigned char)(sum>>6);   // divide by 64 and cast to uchar
   return result;                      // return average reading
}

void coast(void)
{
    PCA0CPH0 = 0;                      // disable PWM
    P0 = 0xff;                         // force all outputs high
}

void reverse (void)
{
   Fwd=!Fwd;                           // toggle direction flag
   CR = 0;                             // Stop PCA0 timer
   PCA0CPH0 = 0;                       // clear duty cycle
   PCA0CPM0 = 0;                       // disable PWM
   P0 = 0xff;                          // force all outputs high
   XBR2 &= ~0x40;                      // disable Crossbar
   if (Fwd)
   {
      XBR0 = ~0x01;                    // don't skip P0.0
      P0   = ~0x08;                    // P0.3 low
   }
   else
   {
      XBR0 = ~0x02;                    // don't skip P0.1
      P0   = ~0x04;                    // P0.2 low
   }
   XBR2 |= 0x40;                       // enable Crossbar
   PCA0CPM0 = 0x42;                    // Module 0, 8-bit PWM Mode
   CR = 1;                             // restart PCA0 timer
}