tools/examples/basics/pwm_piezobuzzer/main.c

   1 /**************************************************************************/
   2 /*!
   3     @file     main.c
   4     @author   K. Townsend (microBuilder.eu)
   5
   6     @section LICENSE
   7
   8     Software License Agreement (BSD License)
   9
  10     Copyright (c) 2011, microBuilder SARL
  11     All rights reserved.
  12
  13     Redistribution and use in source and binary forms, with or without
  14     modification, are permitted provided that the following conditions are met:
  15     1. Redistributions of source code must retain the above copyright
  16     notice, this list of conditions and the following disclaimer.
  17     2. Redistributions in binary form must reproduce the above copyright
  18     notice, this list of conditions and the following disclaimer in the
  19     documentation and/or other materials provided with the distribution.
  20     3. Neither the name of the copyright holders nor the
  21     names of its contributors may be used to endorse or promote products
  22     derived from this software without specific prior written permission.
  23
  24     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
  25     EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  26     WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  27     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
  28     DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  29     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  30     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  31     ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34 */
  35 /**************************************************************************/
  36 #include <stdlib.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39
  40 #include "projectconfig.h"
  41 #include "sysinit.h"
  42
  43 #include "core/gpio/gpio.h"
  44 #include "core/systick/systick.h"
  45
  46 #ifdef CFG_INTERFACE
  47   #include "core/cmd/cmd.h"
  48 #endif
  49
  50 #ifdef CFG_PWM
  51   #include "core/pwm/pwm.h"
  52 #endif
  53
  54 /**************************************************************************/
  55 /*!
  56     Main program entry point.  After reset, normal code execution will
  57     begin here.
  58 */
  59 /**************************************************************************/
  60 int main(void)
  61 {
  62   #ifndef CFG_PWM
  63     #ERROR "CFG_PWM must be enabled in projectconfig.h for this example."
  64   #endif
  65
  66   // Configure cpu and mandatory peripherals
  67   // PWM is initialised in systemInit and defaults to using P1.9
  68   systemInit();
  69
  70   // Set duty cycle to 50% for square wave output
  71   pwmSetDutyCycle(50);
  72
  73   // Frequency can be set anywhere from 2khz and 10khz (4khz is loudest)
  74   // Note: Since this is a 16-bit timer, make sure the delay is not
  75   //       greater than 0xFFFF (65535), though anything 2khz and higher
  76   //       is within an acceptable range
  77   // The piezo buzzer used for this example is the PS1240, available at
  78   // http://www.adafruit.com/index.php?main_page=product_info&cPath=35&products_id=160
  79   pwmSetFrequencyInTicks(CFG_CPU_CCLK / 2000);
  80
  81   uint32_t currentSecond, lastSecond;
  82   currentSecond = lastSecond = 0;
  83
  84   while (1)
  85   {
  86     // Beep the piezo buzzer very briefly once per second, toggling the LED at the same time
  87     currentSecond = systickGetSecondsActive();
  88     // Make sure that at least one second has passed
  89     if (currentSecond != lastSecond)
  90     {
  91       // Update the second tracker
  92       lastSecond = currentSecond;
  93       // Set the LED state and buzzer loudness depending on the current LED state
  94       if (gpioGetValue(CFG_LED_PORT, CFG_LED_PIN) == CFG_LED_OFF)
  95       {
  96         pwmSetFrequencyInTicks(CFG_CPU_CCLK / 4000);            // 4khz (louder)
  97         pwmStartFixed(200);                                     // 2x as long as @ 2khz since it's 2x faster
  98         gpioSetValue (CFG_LED_PORT, CFG_LED_PIN, CFG_LED_ON);   // Turn the LED on
  99       }
 100       else
 101       {
 102         pwmSetFrequencyInTicks(CFG_CPU_CCLK / 2000);            // 2khz (softer)
 103         pwmStartFixed(100);
 104         gpioSetValue (CFG_LED_PORT, CFG_LED_PIN, CFG_LED_OFF);  // Turn the LED off
 105       }
 106     }
 107   }
 108
 109   return 0;
 110 }