Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_ONSEMI/TARGET_NCS36510/pwmout_api.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /**
<> 144:ef7eb2e8f9f7 2 ******************************************************************************
<> 144:ef7eb2e8f9f7 3 * @file pwmout_api.c
<> 144:ef7eb2e8f9f7 4 * @brief Implementation of a PWM driver
<> 144:ef7eb2e8f9f7 5 * @internal
<> 144:ef7eb2e8f9f7 6 * @author ON Semiconductor
<> 144:ef7eb2e8f9f7 7 * $Rev:
<> 144:ef7eb2e8f9f7 8 * $Date:
<> 144:ef7eb2e8f9f7 9 ******************************************************************************
<> 144:ef7eb2e8f9f7 10 * @copyright (c) 2012 ON Semiconductor. All rights reserved.
<> 144:ef7eb2e8f9f7 11 * ON Semiconductor is supplying this software for use with ON Semiconductor
<> 144:ef7eb2e8f9f7 12 * processor based microcontrollers only.
<> 144:ef7eb2e8f9f7 13 *
<> 144:ef7eb2e8f9f7 14 * THIS SOFTWARE IS PROVIDED "AS IS". NO WARRANTIES, WHETHER EXPRESS, IMPLIED
<> 144:ef7eb2e8f9f7 15 * OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
<> 144:ef7eb2e8f9f7 16 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
<> 144:ef7eb2e8f9f7 17 * ON SEMICONDUCTOR SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL,
<> 144:ef7eb2e8f9f7 18 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
<> 144:ef7eb2e8f9f7 19 * @endinternal
<> 144:ef7eb2e8f9f7 20 */
<> 144:ef7eb2e8f9f7 21 #include "pwmout_api.h"
<> 144:ef7eb2e8f9f7 22 #include "PeripheralPins.h"
<> 144:ef7eb2e8f9f7 23 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 24 #include "clock.h"
<> 144:ef7eb2e8f9f7 25
<> 144:ef7eb2e8f9f7 26 #if DEVICE_PWMOUT
<> 144:ef7eb2e8f9f7 27
<> 144:ef7eb2e8f9f7 28 /**
<> 144:ef7eb2e8f9f7 29 * \defgroup hal_pwmout Pwmout hal functions
<> 144:ef7eb2e8f9f7 30 * @{
<> 144:ef7eb2e8f9f7 31 */
<> 144:ef7eb2e8f9f7 32
<> 144:ef7eb2e8f9f7 33 /** Initialize the pwm out peripheral and configure the pin
<> 144:ef7eb2e8f9f7 34 *
<> 144:ef7eb2e8f9f7 35 * @param obj The pwmout object to initialize
<> 144:ef7eb2e8f9f7 36 * @param pin The pwmout pin to initialize
<> 144:ef7eb2e8f9f7 37 */
<> 144:ef7eb2e8f9f7 38 void pwmout_init(pwmout_t *obj, PinName pin)
<> 144:ef7eb2e8f9f7 39 {
<> 144:ef7eb2e8f9f7 40 /* Get the base address of the PWM register using the pinmap functions ; pwmout_s struct contains base address only */
<> 144:ef7eb2e8f9f7 41 PWMName pwm;
<> 144:ef7eb2e8f9f7 42
<> 144:ef7eb2e8f9f7 43 pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 44 MBED_ASSERT(pwm != (PWMName)NC);
<> 144:ef7eb2e8f9f7 45
<> 144:ef7eb2e8f9f7 46 pinmap_pinout(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 47
<> 144:ef7eb2e8f9f7 48 obj->pwmReg = (PwmReg_pt)pwm;
<> 144:ef7eb2e8f9f7 49 MBED_ASSERT(obj->pwmReg != 0x00000000);
<> 144:ef7eb2e8f9f7 50
<> 144:ef7eb2e8f9f7 51 CLOCK_ENABLE(CLOCK_PWM);
<> 144:ef7eb2e8f9f7 52
<> 144:ef7eb2e8f9f7 53 /* Configuration parameters of duty cycle 0x4000B000, and prescaler 0x4000B00C, shall be set to default values */
<> 144:ef7eb2e8f9f7 54 /* Duty cycle shall be 50% and prescaler shall be disabled by default */
<> 144:ef7eb2e8f9f7 55 obj->pwmReg->DUTYCYCLE = 0x80;
<> 144:ef7eb2e8f9f7 56
<> 144:ef7eb2e8f9f7 57 /* Write the PWM output enable register 0x4000B004, to 1 */
<> 144:ef7eb2e8f9f7 58 obj->pwmReg->PWM_ENABLE.WORD = 0x1;
<> 144:ef7eb2e8f9f7 59
<> 144:ef7eb2e8f9f7 60 obj->pwmReg->PRESCALE_DISABLE = 0x1;
<> 144:ef7eb2e8f9f7 61
<> 144:ef7eb2e8f9f7 62 }
<> 144:ef7eb2e8f9f7 63
<> 144:ef7eb2e8f9f7 64 /** Deinitialize the pwmout object
<> 144:ef7eb2e8f9f7 65 *
<> 144:ef7eb2e8f9f7 66 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 67 */
<> 144:ef7eb2e8f9f7 68 void pwmout_free(pwmout_t *obj)
<> 144:ef7eb2e8f9f7 69 {
<> 144:ef7eb2e8f9f7 70 /* Write the PWM output disable register 0x4000B008, to 1 */
<> 144:ef7eb2e8f9f7 71 obj->pwmReg->PWM_DISABLE = 0x1;
<> 144:ef7eb2e8f9f7 72 }
<> 144:ef7eb2e8f9f7 73
<> 144:ef7eb2e8f9f7 74 /** Set the output duty-cycle in range <0.0f, 1.0f>
<> 144:ef7eb2e8f9f7 75 *
<> 144:ef7eb2e8f9f7 76 * Value 0.0f represents 0 percentage, 1.0f represents 100 percent.
<> 144:ef7eb2e8f9f7 77 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 78 * @param percent The floating-point percentage number
<> 144:ef7eb2e8f9f7 79 */
<> 144:ef7eb2e8f9f7 80 void pwmout_write(pwmout_t *obj, float percent)
<> 144:ef7eb2e8f9f7 81 {
<> 144:ef7eb2e8f9f7 82 if (percent == 0.0) {
<> 144:ef7eb2e8f9f7 83 obj->pwmReg->DUTYCYCLE = 0x00;
<> 144:ef7eb2e8f9f7 84 } else if (percent == 1.0) {
<> 144:ef7eb2e8f9f7 85 obj->pwmReg->DUTYCYCLE = 0xFF;
<> 144:ef7eb2e8f9f7 86 } else {
<> 144:ef7eb2e8f9f7 87 /* Write the duty cycle config register 0x4000B000, with the value passed on */
<> 144:ef7eb2e8f9f7 88 /* ((percent * 255) + 1) is the duty cycle. Plus 1 is for accounting for round off errors; like a ceil function */
<> 144:ef7eb2e8f9f7 89 obj->pwmReg->DUTYCYCLE = (uint8_t)((percent * 255) + 1);
<> 144:ef7eb2e8f9f7 90 }
<> 144:ef7eb2e8f9f7 91 }
<> 144:ef7eb2e8f9f7 92
<> 144:ef7eb2e8f9f7 93 /** Read the current float-point output duty-cycle
<> 144:ef7eb2e8f9f7 94 *
<> 144:ef7eb2e8f9f7 95 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 96 * @return A floating-point output duty-cycle
<> 144:ef7eb2e8f9f7 97 */
<> 144:ef7eb2e8f9f7 98 float pwmout_read(pwmout_t *obj)
<> 144:ef7eb2e8f9f7 99 {
<> 144:ef7eb2e8f9f7 100 float retVal = 0.0;
<> 144:ef7eb2e8f9f7 101 float dc = 0.0;
<> 144:ef7eb2e8f9f7 102
<> 144:ef7eb2e8f9f7 103 /* Read out the value of duty cycle register 0x4000B000 and return as a percent */
<> 144:ef7eb2e8f9f7 104 /* Read value / 255 is the percent returned */
<> 144:ef7eb2e8f9f7 105 dc = obj->pwmReg->DUTYCYCLE;
<> 144:ef7eb2e8f9f7 106 retVal = dc/ (float)255;
<> 144:ef7eb2e8f9f7 107
<> 144:ef7eb2e8f9f7 108 return(retVal);
<> 144:ef7eb2e8f9f7 109 }
<> 144:ef7eb2e8f9f7 110
<> 144:ef7eb2e8f9f7 111 /** Set the PWM period specified in seconds, keeping the duty cycle the same
<> 144:ef7eb2e8f9f7 112 *
<> 144:ef7eb2e8f9f7 113 * Periods smaller than microseconds (the lowest resolution) are set to zero.
<> 144:ef7eb2e8f9f7 114 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 115 * @param seconds The floating-point seconds period
<> 144:ef7eb2e8f9f7 116 */
<> 144:ef7eb2e8f9f7 117 void pwmout_period(pwmout_t *obj, float seconds)
<> 144:ef7eb2e8f9f7 118 {
<> 144:ef7eb2e8f9f7 119 /* Cannot be configured, prescaler is either 256 or 4096 */
<> 144:ef7eb2e8f9f7 120 return;
<> 144:ef7eb2e8f9f7 121 }
<> 144:ef7eb2e8f9f7 122
<> 144:ef7eb2e8f9f7 123 /** Set the PWM period specified in miliseconds, keeping the duty cycle the same
<> 144:ef7eb2e8f9f7 124 *
<> 144:ef7eb2e8f9f7 125 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 126 * @param ms The milisecond period
<> 144:ef7eb2e8f9f7 127 */
<> 144:ef7eb2e8f9f7 128 void pwmout_period_ms(pwmout_t *obj, int ms)
<> 144:ef7eb2e8f9f7 129 {
<> 144:ef7eb2e8f9f7 130 /* Cannot be configured, prescaler is either 256 or 4096 */
<> 144:ef7eb2e8f9f7 131 return;
<> 144:ef7eb2e8f9f7 132 }
<> 144:ef7eb2e8f9f7 133
<> 144:ef7eb2e8f9f7 134 /** Set the PWM period specified in microseconds, keeping the duty cycle the same
<> 144:ef7eb2e8f9f7 135 *
<> 144:ef7eb2e8f9f7 136 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 137 * @param us The microsecond period
<> 144:ef7eb2e8f9f7 138 */
<> 144:ef7eb2e8f9f7 139 void pwmout_period_us(pwmout_t *obj, int us)
<> 144:ef7eb2e8f9f7 140 {
<> 144:ef7eb2e8f9f7 141 /* Cannot be configured, prescaler is either 256 or 4096 */
<> 144:ef7eb2e8f9f7 142 return;
<> 144:ef7eb2e8f9f7 143 }
<> 144:ef7eb2e8f9f7 144
<> 144:ef7eb2e8f9f7 145 /** Set the PWM pulsewidth specified in seconds, keeping the period the same.
<> 144:ef7eb2e8f9f7 146 *
<> 144:ef7eb2e8f9f7 147 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 148 * @param seconds The floating-point pulsewidth in seconds
<> 144:ef7eb2e8f9f7 149 */
<> 144:ef7eb2e8f9f7 150 void pwmout_pulsewidth(pwmout_t *obj, float seconds)
<> 144:ef7eb2e8f9f7 151 {
<> 144:ef7eb2e8f9f7 152 /* Pulse width can never be in seconds since the period
<> 144:ef7eb2e8f9f7 153 * itself is limited to either 8uSec or 128uSec
<> 144:ef7eb2e8f9f7 154 */
<> 144:ef7eb2e8f9f7 155 return;
<> 144:ef7eb2e8f9f7 156 }
<> 144:ef7eb2e8f9f7 157
<> 144:ef7eb2e8f9f7 158 /** Set the PWM pulsewidth specified in miliseconds, keeping the period the same.
<> 144:ef7eb2e8f9f7 159 *
<> 144:ef7eb2e8f9f7 160 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 161 * @param ms The floating-point pulsewidth in miliseconds
<> 144:ef7eb2e8f9f7 162 */
<> 144:ef7eb2e8f9f7 163 void pwmout_pulsewidth_ms(pwmout_t *obj, int ms)
<> 144:ef7eb2e8f9f7 164 {
<> 144:ef7eb2e8f9f7 165
<> 144:ef7eb2e8f9f7 166 /* Pulse width can never be in seconds since the period
<> 144:ef7eb2e8f9f7 167 * itself is limited to either 8uSec or 128uSec
<> 144:ef7eb2e8f9f7 168 */
<> 144:ef7eb2e8f9f7 169 return;
<> 144:ef7eb2e8f9f7 170 }
<> 144:ef7eb2e8f9f7 171
<> 144:ef7eb2e8f9f7 172 /** Set the PWM pulsewidth specified in microseconds, keeping the period the same.
<> 144:ef7eb2e8f9f7 173 *
<> 144:ef7eb2e8f9f7 174 * @param obj The pwmout object
<> 144:ef7eb2e8f9f7 175 * @param us The floating-point pulsewidth in microseconds
<> 144:ef7eb2e8f9f7 176 */
<> 144:ef7eb2e8f9f7 177 void pwmout_pulsewidth_us(pwmout_t *obj, int us)
<> 144:ef7eb2e8f9f7 178 {
<> 144:ef7eb2e8f9f7 179 int pulseWidth = 0;
<> 144:ef7eb2e8f9f7 180
<> 144:ef7eb2e8f9f7 181 /* Check if the uSec value is greater than 128uSec, if so reject */
<> 144:ef7eb2e8f9f7 182 if (us > 128) {
<> 144:ef7eb2e8f9f7 183 return;
<> 144:ef7eb2e8f9f7 184 }
<> 144:ef7eb2e8f9f7 185 /* If pulsewidth is less than 128uSec, set the prescaler to 4096
<> 144:ef7eb2e8f9f7 186 * by enabling prescale register 0x4000B00C to 1 */
<> 144:ef7eb2e8f9f7 187 obj->pwmReg->PRESCALE_ENABLE.WORD = 0x1;
<> 144:ef7eb2e8f9f7 188
<> 144:ef7eb2e8f9f7 189 /* Calculate the duty cycle based on the width of the pulse */
<> 144:ef7eb2e8f9f7 190 /* ((255 * us) / 128) + 1 = duty cycle */
<> 144:ef7eb2e8f9f7 191 pulseWidth = (int)((float)(255 * us)/(float)128) + 1;
<> 144:ef7eb2e8f9f7 192 if (us == 0) {
<> 144:ef7eb2e8f9f7 193 obj->pwmReg->DUTYCYCLE = 0x0;
<> 144:ef7eb2e8f9f7 194 } else if (us == 128) {
<> 144:ef7eb2e8f9f7 195 obj->pwmReg->DUTYCYCLE = 0xFF;
<> 144:ef7eb2e8f9f7 196 } else {
<> 144:ef7eb2e8f9f7 197 obj->pwmReg->DUTYCYCLE = (uint8_t)pulseWidth;
<> 144:ef7eb2e8f9f7 198 }
<> 144:ef7eb2e8f9f7 199 }
<> 144:ef7eb2e8f9f7 200
<> 144:ef7eb2e8f9f7 201 /**@}*/
<> 144:ef7eb2e8f9f7 202
<> 144:ef7eb2e8f9f7 203 #endif // DEVICE_PWMOUT