mirror of https://github.com/ARMmbed/mbed-os.git
210 lines
6.4 KiB
C
210 lines
6.4 KiB
C
/**
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******************************************************************************
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* @file pwmout_api.c
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* @brief Implementation of a PWM driver
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* @internal
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* @author ON Semiconductor
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* $Rev:
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* $Date:
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******************************************************************************
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* Copyright 2016 Semiconductor Components Industries LLC (d/b/a “ON Semiconductor”).
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* All rights reserved. This software and/or documentation is licensed by ON Semiconductor
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* under limited terms and conditions. The terms and conditions pertaining to the software
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* and/or documentation are available at http://www.onsemi.com/site/pdf/ONSEMI_T&C.pdf
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* (“ON Semiconductor Standard Terms and Conditions of Sale, Section 8 Software”) and
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* if applicable the software license agreement. Do not use this software and/or
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* documentation unless you have carefully read and you agree to the limited terms and
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* conditions. By using this software and/or documentation, you agree to the limited
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* terms and conditions.
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*
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* THIS SOFTWARE IS PROVIDED "AS IS". NO WARRANTIES, WHETHER EXPRESS, IMPLIED
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* OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
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* ON SEMICONDUCTOR SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL,
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* INCIDENTAL, OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
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* @endinternal
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*/
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#include "pwmout_api.h"
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#include "PeripheralPins.h"
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#include "mbed_assert.h"
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#include "clock.h"
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#if DEVICE_PWMOUT
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/**
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* \defgroup hal_pwmout Pwmout hal functions
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* @{
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*/
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/** Initialize the pwm out peripheral and configure the pin
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*
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* @param obj The pwmout object to initialize
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* @param pin The pwmout pin to initialize
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*/
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void pwmout_init(pwmout_t *obj, PinName pin)
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{
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/* Get the base address of the PWM register using the pinmap functions ; pwmout_s struct contains base address only */
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PWMName pwm;
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pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
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MBED_ASSERT(pwm != (PWMName)NC);
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pinmap_pinout(pin, PinMap_PWM);
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obj->pwmReg = (PwmReg_pt)pwm;
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MBED_ASSERT(obj->pwmReg != 0x00000000);
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CLOCK_ENABLE(CLOCK_PWM);
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/* Configuration parameters of duty cycle 0x4000B000, and prescaler 0x4000B00C, shall be set to default values */
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/* Duty cycle shall be 50% and prescaler shall be disabled by default */
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obj->pwmReg->DUTYCYCLE = 0x80;
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/* Write the PWM output enable register 0x4000B004, to 1 */
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obj->pwmReg->PWM_ENABLE = 0x1;
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obj->pwmReg->PRESCALE_DISABLE = 0x1;
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}
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/** Deinitialize the pwmout object
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*
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* @param obj The pwmout object
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*/
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void pwmout_free(pwmout_t *obj)
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{
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/* Write the PWM output disable register 0x4000B008, to 1 */
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obj->pwmReg->PWM_DISABLE = 0x1;
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}
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/** Set the output duty-cycle in range <0.0f, 1.0f>
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*
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* Value 0.0f represents 0 percentage, 1.0f represents 100 percent.
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* @param obj The pwmout object
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* @param percent The floating-point percentage number
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*/
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void pwmout_write(pwmout_t *obj, float percent)
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{
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if (percent == 0.0) {
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obj->pwmReg->DUTYCYCLE = 0x00;
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} else if (percent == 1.0) {
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obj->pwmReg->DUTYCYCLE = 0xFF;
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} else {
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/* Write the duty cycle config register 0x4000B000, with the value passed on */
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/* ((percent * 255) + 1) is the duty cycle. Plus 1 is for accounting for round off errors; like a ceil function */
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obj->pwmReg->DUTYCYCLE = (uint8_t)((percent * 255) + 1);
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}
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}
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/** Read the current float-point output duty-cycle
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*
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* @param obj The pwmout object
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* @return A floating-point output duty-cycle
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*/
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float pwmout_read(pwmout_t *obj)
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{
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float retVal = 0.0;
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float dc = 0.0;
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/* Read out the value of duty cycle register 0x4000B000 and return as a percent */
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/* Read value / 255 is the percent returned */
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dc = obj->pwmReg->DUTYCYCLE;
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retVal = dc/ (float)255;
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return(retVal);
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}
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/** Set the PWM period specified in seconds, keeping the duty cycle the same
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*
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* Periods smaller than microseconds (the lowest resolution) are set to zero.
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* @param obj The pwmout object
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* @param seconds The floating-point seconds period
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*/
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void pwmout_period(pwmout_t *obj, float seconds)
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{
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/* Cannot be configured, prescaler is either 256 or 4096 */
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return;
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}
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/** Set the PWM period specified in miliseconds, keeping the duty cycle the same
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*
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* @param obj The pwmout object
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* @param ms The milisecond period
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*/
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void pwmout_period_ms(pwmout_t *obj, int ms)
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{
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/* Cannot be configured, prescaler is either 256 or 4096 */
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return;
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}
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/** Set the PWM period specified in microseconds, keeping the duty cycle the same
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*
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* @param obj The pwmout object
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* @param us The microsecond period
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*/
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void pwmout_period_us(pwmout_t *obj, int us)
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{
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/* Cannot be configured, prescaler is either 256 or 4096 */
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return;
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}
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/** Set the PWM pulsewidth specified in seconds, keeping the period the same.
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*
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* @param obj The pwmout object
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* @param seconds The floating-point pulsewidth in seconds
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*/
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void pwmout_pulsewidth(pwmout_t *obj, float seconds)
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{
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/* Pulse width can never be in seconds since the period
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* itself is limited to either 8uSec or 128uSec
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*/
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return;
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}
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/** Set the PWM pulsewidth specified in miliseconds, keeping the period the same.
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*
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* @param obj The pwmout object
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* @param ms The floating-point pulsewidth in miliseconds
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*/
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void pwmout_pulsewidth_ms(pwmout_t *obj, int ms)
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{
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/* Pulse width can never be in seconds since the period
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* itself is limited to either 8uSec or 128uSec
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*/
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return;
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}
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/** Set the PWM pulsewidth specified in microseconds, keeping the period the same.
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*
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* @param obj The pwmout object
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* @param us The floating-point pulsewidth in microseconds
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*/
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void pwmout_pulsewidth_us(pwmout_t *obj, int us)
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{
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int pulseWidth = 0;
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/* Check if the uSec value is greater than 128uSec, if so reject */
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if (us > 128) {
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return;
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}
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/* If pulsewidth is less than 128uSec, set the prescaler to 4096
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* by enabling prescale register 0x4000B00C to 1 */
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obj->pwmReg->PRESCALE_ENABLE = 0x1;
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/* Calculate the duty cycle based on the width of the pulse */
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/* ((255 * us) / 128) + 1 = duty cycle */
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pulseWidth = (int)((float)(255 * us)/(float)128) + 1;
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if (us == 0) {
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obj->pwmReg->DUTYCYCLE = 0x0;
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} else if (us == 128) {
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obj->pwmReg->DUTYCYCLE = 0xFF;
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} else {
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obj->pwmReg->DUTYCYCLE = (uint8_t)pulseWidth;
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}
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}
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/**@}*/
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#endif // DEVICE_PWMOUT
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