Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

api/PwmOut.h@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 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #ifndef MBED_PWMOUT_H
<> 144:ef7eb2e8f9f7 17 #define MBED_PWMOUT_H
<> 144:ef7eb2e8f9f7 18
<> 144:ef7eb2e8f9f7 19 #include "platform.h"
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 #if DEVICE_PWMOUT
<> 144:ef7eb2e8f9f7 22 #include "pwmout_api.h"
<> 144:ef7eb2e8f9f7 23 #include "critical.h"
<> 144:ef7eb2e8f9f7 24
<> 144:ef7eb2e8f9f7 25 namespace mbed {
<> 144:ef7eb2e8f9f7 26
<> 144:ef7eb2e8f9f7 27 /** A pulse-width modulation digital output
<> 144:ef7eb2e8f9f7 28 *
<> 144:ef7eb2e8f9f7 29 * @Note Synchronization level: Interrupt safe
<> 144:ef7eb2e8f9f7 30 *
<> 144:ef7eb2e8f9f7 31 * Example
<> 144:ef7eb2e8f9f7 32 * @code
<> 144:ef7eb2e8f9f7 33 * // Fade a led on.
<> 144:ef7eb2e8f9f7 34 * #include "mbed.h"
<> 144:ef7eb2e8f9f7 35 *
<> 144:ef7eb2e8f9f7 36 * PwmOut led(LED1);
<> 144:ef7eb2e8f9f7 37 *
<> 144:ef7eb2e8f9f7 38 * int main() {
<> 144:ef7eb2e8f9f7 39 * while(1) {
<> 144:ef7eb2e8f9f7 40 * led = led + 0.01;
<> 144:ef7eb2e8f9f7 41 * wait(0.2);
<> 144:ef7eb2e8f9f7 42 * if(led == 1.0) {
<> 144:ef7eb2e8f9f7 43 * led = 0;
<> 144:ef7eb2e8f9f7 44 * }
<> 144:ef7eb2e8f9f7 45 * }
<> 144:ef7eb2e8f9f7 46 * }
<> 144:ef7eb2e8f9f7 47 * @endcode
<> 144:ef7eb2e8f9f7 48 *
<> 144:ef7eb2e8f9f7 49 * @note
<> 144:ef7eb2e8f9f7 50 * On the LPC1768 and LPC2368, the PWMs all share the same
<> 144:ef7eb2e8f9f7 51 * period - if you change the period for one, you change it for all.
<> 144:ef7eb2e8f9f7 52 * Although routines that change the period maintain the duty cycle
<> 144:ef7eb2e8f9f7 53 * for its PWM, all other PWMs will require their duty cycle to be
<> 144:ef7eb2e8f9f7 54 * refreshed.
<> 144:ef7eb2e8f9f7 55 */
<> 144:ef7eb2e8f9f7 56 class PwmOut {
<> 144:ef7eb2e8f9f7 57
<> 144:ef7eb2e8f9f7 58 public:
<> 144:ef7eb2e8f9f7 59
<> 144:ef7eb2e8f9f7 60 /** Create a PwmOut connected to the specified pin
<> 144:ef7eb2e8f9f7 61 *
<> 144:ef7eb2e8f9f7 62 * @param pin PwmOut pin to connect to
<> 144:ef7eb2e8f9f7 63 */
<> 144:ef7eb2e8f9f7 64 PwmOut(PinName pin) {
<> 144:ef7eb2e8f9f7 65 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 66 pwmout_init(&_pwm, pin);
<> 144:ef7eb2e8f9f7 67 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 68 }
<> 144:ef7eb2e8f9f7 69
<> 144:ef7eb2e8f9f7 70 /** Set the ouput duty-cycle, specified as a percentage (float)
<> 144:ef7eb2e8f9f7 71 *
<> 144:ef7eb2e8f9f7 72 * @param value A floating-point value representing the output duty-cycle,
<> 144:ef7eb2e8f9f7 73 * specified as a percentage. The value should lie between
<> 144:ef7eb2e8f9f7 74 * 0.0f (representing on 0%) and 1.0f (representing on 100%).
<> 144:ef7eb2e8f9f7 75 * Values outside this range will be saturated to 0.0f or 1.0f.
<> 144:ef7eb2e8f9f7 76 */
<> 144:ef7eb2e8f9f7 77 void write(float value) {
<> 144:ef7eb2e8f9f7 78 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 79 pwmout_write(&_pwm, value);
<> 144:ef7eb2e8f9f7 80 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 81 }
<> 144:ef7eb2e8f9f7 82
<> 144:ef7eb2e8f9f7 83 /** Return the current output duty-cycle setting, measured as a percentage (float)
<> 144:ef7eb2e8f9f7 84 *
<> 144:ef7eb2e8f9f7 85 * @returns
<> 144:ef7eb2e8f9f7 86 * A floating-point value representing the current duty-cycle being output on the pin,
<> 144:ef7eb2e8f9f7 87 * measured as a percentage. The returned value will lie between
<> 144:ef7eb2e8f9f7 88 * 0.0f (representing on 0%) and 1.0f (representing on 100%).
<> 144:ef7eb2e8f9f7 89 *
<> 144:ef7eb2e8f9f7 90 * @note
<> 144:ef7eb2e8f9f7 91 * This value may not match exactly the value set by a previous <write>.
<> 144:ef7eb2e8f9f7 92 */
<> 144:ef7eb2e8f9f7 93 float read() {
<> 144:ef7eb2e8f9f7 94 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 95 float val = pwmout_read(&_pwm);
<> 144:ef7eb2e8f9f7 96 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 97 return val;
<> 144:ef7eb2e8f9f7 98 }
<> 144:ef7eb2e8f9f7 99
<> 144:ef7eb2e8f9f7 100 /** Set the PWM period, specified in seconds (float), keeping the duty cycle the same.
<> 144:ef7eb2e8f9f7 101 *
<> 144:ef7eb2e8f9f7 102 * @note
<> 144:ef7eb2e8f9f7 103 * The resolution is currently in microseconds; periods smaller than this
<> 144:ef7eb2e8f9f7 104 * will be set to zero.
<> 144:ef7eb2e8f9f7 105 */
<> 144:ef7eb2e8f9f7 106 void period(float seconds) {
<> 144:ef7eb2e8f9f7 107 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 108 pwmout_period(&_pwm, seconds);
<> 144:ef7eb2e8f9f7 109 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 110 }
<> 144:ef7eb2e8f9f7 111
<> 144:ef7eb2e8f9f7 112 /** Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same.
<> 144:ef7eb2e8f9f7 113 */
<> 144:ef7eb2e8f9f7 114 void period_ms(int ms) {
<> 144:ef7eb2e8f9f7 115 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 116 pwmout_period_ms(&_pwm, ms);
<> 144:ef7eb2e8f9f7 117 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 118 }
<> 144:ef7eb2e8f9f7 119
<> 144:ef7eb2e8f9f7 120 /** Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same.
<> 144:ef7eb2e8f9f7 121 */
<> 144:ef7eb2e8f9f7 122 void period_us(int us) {
<> 144:ef7eb2e8f9f7 123 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 124 pwmout_period_us(&_pwm, us);
<> 144:ef7eb2e8f9f7 125 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 126 }
<> 144:ef7eb2e8f9f7 127
<> 144:ef7eb2e8f9f7 128 /** Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.
<> 144:ef7eb2e8f9f7 129 */
<> 144:ef7eb2e8f9f7 130 void pulsewidth(float seconds) {
<> 144:ef7eb2e8f9f7 131 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 132 pwmout_pulsewidth(&_pwm, seconds);
<> 144:ef7eb2e8f9f7 133 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 134 }
<> 144:ef7eb2e8f9f7 135
<> 144:ef7eb2e8f9f7 136 /** Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.
<> 144:ef7eb2e8f9f7 137 */
<> 144:ef7eb2e8f9f7 138 void pulsewidth_ms(int ms) {
<> 144:ef7eb2e8f9f7 139 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 140 pwmout_pulsewidth_ms(&_pwm, ms);
<> 144:ef7eb2e8f9f7 141 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 142 }
<> 144:ef7eb2e8f9f7 143
<> 144:ef7eb2e8f9f7 144 /** Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.
<> 144:ef7eb2e8f9f7 145 */
<> 144:ef7eb2e8f9f7 146 void pulsewidth_us(int us) {
<> 144:ef7eb2e8f9f7 147 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 148 pwmout_pulsewidth_us(&_pwm, us);
<> 144:ef7eb2e8f9f7 149 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 150 }
<> 144:ef7eb2e8f9f7 151
<> 144:ef7eb2e8f9f7 152 /** A operator shorthand for write()
<> 144:ef7eb2e8f9f7 153 */
<> 144:ef7eb2e8f9f7 154 PwmOut& operator= (float value) {
<> 144:ef7eb2e8f9f7 155 // Underlying call is thread safe
<> 144:ef7eb2e8f9f7 156 write(value);
<> 144:ef7eb2e8f9f7 157 return *this;
<> 144:ef7eb2e8f9f7 158 }
<> 144:ef7eb2e8f9f7 159
<> 144:ef7eb2e8f9f7 160 PwmOut& operator= (PwmOut& rhs) {
<> 144:ef7eb2e8f9f7 161 // Underlying call is thread safe
<> 144:ef7eb2e8f9f7 162 write(rhs.read());
<> 144:ef7eb2e8f9f7 163 return *this;
<> 144:ef7eb2e8f9f7 164 }
<> 144:ef7eb2e8f9f7 165
<> 144:ef7eb2e8f9f7 166 /** An operator shorthand for read()
<> 144:ef7eb2e8f9f7 167 */
<> 144:ef7eb2e8f9f7 168 operator float() {
<> 144:ef7eb2e8f9f7 169 // Underlying call is thread safe
<> 144:ef7eb2e8f9f7 170 return read();
<> 144:ef7eb2e8f9f7 171 }
<> 144:ef7eb2e8f9f7 172
<> 144:ef7eb2e8f9f7 173 protected:
<> 144:ef7eb2e8f9f7 174 pwmout_t _pwm;
<> 144:ef7eb2e8f9f7 175 };
<> 144:ef7eb2e8f9f7 176
<> 144:ef7eb2e8f9f7 177 } // namespace mbed
<> 144:ef7eb2e8f9f7 178
<> 144:ef7eb2e8f9f7 179 #endif
<> 144:ef7eb2e8f9f7 180
<> 144:ef7eb2e8f9f7 181 #endif