CT16B1_PWM.cpp

00001  /**
00002  * @file    CT16B1_PWM.cpp
00003  * @brief   Small driver to user CT16B1 for PWM
00004  *
00005  * @author  Jeroen Lodder
00006  * @date        Oktober 2013
00007  *
00008  * @note        This only uses MAT 1
00009  * @{
00010  */
00011 #include "mbed.h"
00012 #include "CT16B1_PWM.h"
00013 
00014 /* NOTICE: THIS MODULE ONLY WORKS FOR MAT 1 */
00015 
00016 /* Static makes them private to this module */  
00017 volatile static uint8_t  stage  = 0;         /**< @brief Stage identifier for mat2/3 swap */
00018 volatile static uint16_t period     = 0;       /**< @brief PWM Period register */
00019 volatile static uint16_t mat[4];             /**< @brief PWM Mat output registers */
00020 volatile static uint16_t default_period_us;  /**< @brief Given period in us */
00021 volatile static uint16_t defaultstate;       /**< @brief Default PWM state on init */
00022 volatile static uint16_t prescaler;          /**< @brief Given prescaler */
00023 
00024 /**
00025  * @brief   Initializes PWM
00026  *
00027  * @param[in] period_us     Period in us, when prescaler is 48
00028  * @param[in] defaultstate  State after initializing
00029  * @param[in] prescaler         Divider from AHBCLK
00030  * @note Prescaler 48 gives 1 us timer ticks
00031  * @note Run Start() to start pwm
00032  */
00033 void CT16B1_initpwm(uint16_t period_arg, uint16_t defaultstate, uint16_t prescaler_arg){
00034         // Calculte period
00035         period      = period_arg;
00036         prescaler = prescaler_arg;
00037 
00038         // Store latest setting
00039         mat[0] = defaultstate;
00040         mat[1] = defaultstate;
00041         mat[2] = defaultstate;
00042         mat[3] = defaultstate;
00043 
00044         //  Enable timer clock, and GPIO
00045         LPC_SYSCON->SYSAHBCLKCTRL |= (1<<6)|(1<<8);
00046 
00047         // Config timer
00048         LPC_CT16B1->IR      = 0x5F;                         // Clear int 
00049         LPC_CT16B1->TCR     = 2;                                // Reset
00050         LPC_CT16B1->PR      = prescaler; 
00051         LPC_CT16B1->CCR     = 0;    // No capture
00052         LPC_CT16B1->EMR     =   0;  // Not required, refer to PWMC
00053         LPC_CT16B1->CTCR    =   0;  // No special counters mode
00054         
00055         // Config mat 1
00056         LPC_CT16B1->PWMC        =   (0<<0)|(1<<1)|(0<<2)|(0<<3);    // MAT1 only
00057         LPC_CT16B1->MCR         = (1<<10);          // Reset on MR3
00058         LPC_CT16B1->MR3         = period_arg;
00059         LPC_CT16B1->MR1         = defaultstate;
00060         // Config met 1 IO
00061         LPC_IOCON->PIO0_22  = 0x2 | (0x1<<3) ;  // GPIO
00062         // Take timer out of reset
00063         LPC_CT16B1->TCR     = 0;
00064 }
00065 
00066 /**
00067  * @brief   Re-Initializes PWM
00068  */
00069 void CT16B1_reinitpwm(void){
00070     CT16B1_initpwm(default_period_us, defaultstate, prescaler   );
00071 }
00072 
00073 /**
00074  * @brief   Start PWM
00075  */
00076 void CT16B1_start(void){
00077     LPC_CT16B1->TCR     = 1;        // Enable
00078 }
00079 
00080 /**
00081  * @brief   Stop PWM
00082  * @param[in] state     PWM output state when pwm disabled
00083  */
00084 void CT16B1_deinit(uint8_t state){
00085   LPC_CT16B1->TCR       = 2;        // Disable and reset counter
00086     // Set all to GPIO
00087     LPC_IOCON->PIO0_22  = 0x0 | (0x1<<3) ;  // GPIO
00088     LPC_GPIO->DIR[0]    |= (1<<22);
00089     LPC_GPIO->CLR[0]    |= (1<<22);
00090 }
00091 
00092 /**
00093  * @brief  Reload all match compare registers
00094  */
00095 void CT16B1_reload_mat(void){
00096     LPC_CT16B1->MR1 = mat[1]; 
00097     LPC_CT16B1->MR3 = period;
00098 }
00099 
00100 /**
00101  * @brief   Set channel PWM
00102  */
00103 void CT16B1_set(uint8_t matnr, uint16_t value){
00104     mat[matnr] = value;
00105     CT16B1_reload_mat();
00106 }
00107 
00108 /**
00109  * @brief   Wait for timer to reach 0
00110  */
00111 void CT16B1_wait_refresh(void){
00112     if( (LPC_CT16B1->TCR & 1) )
00113         while(LPC_CT16B1->TC != 0);
00114 }
00115 
00116 /**
00117  * @brief  Return period
00118  */
00119 uint16_t CT16B1_get_period(void){
00120     return period;
00121 }
00122 
00123 /**
00124  * @brief   Return 1 if timer is started
00125  */
00126 uint32_t CT16B1_isStarted(void){
00127     return LPC_CT16B1->TCR & 1;
00128 }
00129 /**
00130  *@}
00131  */
00132