Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Maxim/TARGET_MAX32620/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 * Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Permission is hereby granted, free of charge, to any person obtaining a
<> 144:ef7eb2e8f9f7 5 * copy of this software and associated documentation files (the "Software"),
<> 144:ef7eb2e8f9f7 6 * to deal in the Software without restriction, including without limitation
<> 144:ef7eb2e8f9f7 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
<> 144:ef7eb2e8f9f7 8 * and/or sell copies of the Software, and to permit persons to whom the
<> 144:ef7eb2e8f9f7 9 * Software is furnished to do so, subject to the following conditions:
<> 144:ef7eb2e8f9f7 10 *
<> 144:ef7eb2e8f9f7 11 * The above copyright notice and this permission notice shall be included
<> 144:ef7eb2e8f9f7 12 * in all copies or substantial portions of the Software.
<> 144:ef7eb2e8f9f7 13 *
<> 144:ef7eb2e8f9f7 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
<> 144:ef7eb2e8f9f7 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
<> 144:ef7eb2e8f9f7 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
<> 144:ef7eb2e8f9f7 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
<> 144:ef7eb2e8f9f7 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
<> 144:ef7eb2e8f9f7 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
<> 144:ef7eb2e8f9f7 20 * OTHER DEALINGS IN THE SOFTWARE.
<> 144:ef7eb2e8f9f7 21 *
<> 144:ef7eb2e8f9f7 22 * Except as contained in this notice, the name of Maxim Integrated
<> 144:ef7eb2e8f9f7 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
<> 144:ef7eb2e8f9f7 24 * Products, Inc. Branding Policy.
<> 144:ef7eb2e8f9f7 25 *
<> 144:ef7eb2e8f9f7 26 * The mere transfer of this software does not imply any licenses
<> 144:ef7eb2e8f9f7 27 * of trade secrets, proprietary technology, copyrights, patents,
<> 144:ef7eb2e8f9f7 28 * trademarks, maskwork rights, or any other form of intellectual
<> 144:ef7eb2e8f9f7 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
<> 144:ef7eb2e8f9f7 30 * ownership rights.
<> 144:ef7eb2e8f9f7 31 *******************************************************************************
<> 144:ef7eb2e8f9f7 32 */
<> 144:ef7eb2e8f9f7 33
<> 144:ef7eb2e8f9f7 34 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 35 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 36 #include "pwmout_api.h"
<> 144:ef7eb2e8f9f7 37 #include "pinmap.h"
<> 144:ef7eb2e8f9f7 38 #include "clkman_regs.h"
<> 144:ef7eb2e8f9f7 39 #include "PeripheralPins.h"
<> 144:ef7eb2e8f9f7 40
<> 144:ef7eb2e8f9f7 41 //******************************************************************************
<> 144:ef7eb2e8f9f7 42 void pwmout_init(pwmout_t* obj, PinName pin)
<> 144:ef7eb2e8f9f7 43 {
<> 144:ef7eb2e8f9f7 44 // Make sure the pin is free for GPIO use
<> 144:ef7eb2e8f9f7 45 unsigned int port = (unsigned int)pin >> PORT_SHIFT;
<> 144:ef7eb2e8f9f7 46 unsigned int port_pin = (unsigned int)pin & ~(0xFFFFFFFF << PORT_SHIFT);
<> 144:ef7eb2e8f9f7 47 MBED_ASSERT(MXC_GPIO->free[port] & (0x1 << port_pin));
<> 144:ef7eb2e8f9f7 48
<> 144:ef7eb2e8f9f7 49 int i = 0;
<> 144:ef7eb2e8f9f7 50 PinMap pwm = PinMap_PWM[0];
<> 144:ef7eb2e8f9f7 51
<> 144:ef7eb2e8f9f7 52 // Check if there is a pulse train already active on this port
<> 144:ef7eb2e8f9f7 53 int pin_func = (MXC_GPIO->func_sel[port] & (0xF << (port_pin*4))) >> (port_pin*4);
<> 144:ef7eb2e8f9f7 54 MBED_ASSERT((pin_func < 1) || (pin_func > 3));
<> 144:ef7eb2e8f9f7 55
<> 144:ef7eb2e8f9f7 56 // Search through PinMap_PWM to find the pin
<> 144:ef7eb2e8f9f7 57 while (pwm.pin != pin) {
<> 144:ef7eb2e8f9f7 58 pwm = PinMap_PWM[++i];
<> 144:ef7eb2e8f9f7 59 }
<> 144:ef7eb2e8f9f7 60
<> 144:ef7eb2e8f9f7 61 // Find a free PT instance on this pin
<> 144:ef7eb2e8f9f7 62 while (pwm.pin == pin) {
<> 144:ef7eb2e8f9f7 63
<> 144:ef7eb2e8f9f7 64 // Check to see if this PT instance is free
<> 144:ef7eb2e8f9f7 65 if (((mxc_pt_regs_t*)pwm.peripheral)->rate_length & MXC_F_PT_RATE_LENGTH_MODE) {
<> 144:ef7eb2e8f9f7 66 break;
<> 144:ef7eb2e8f9f7 67 }
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 pwm = PinMap_PWM[++i];
<> 144:ef7eb2e8f9f7 70
<> 144:ef7eb2e8f9f7 71 // Raise an assertion if we can not allocate another PT instance.
<> 144:ef7eb2e8f9f7 72 MBED_ASSERT(pwm.pin == pin);
<> 144:ef7eb2e8f9f7 73 }
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 // Enable the clock
<> 144:ef7eb2e8f9f7 76 MXC_CLKMAN->sys_clk_ctrl_7_pt = MXC_S_CLKMAN_CLK_SCALE_DIV_1;
<> 144:ef7eb2e8f9f7 77
<> 144:ef7eb2e8f9f7 78 // Set the obj pointer to the propper PWM instance
<> 144:ef7eb2e8f9f7 79 obj->pwm = (mxc_pt_regs_t*)pwm.peripheral;
<> 144:ef7eb2e8f9f7 80
<> 144:ef7eb2e8f9f7 81 // Initialize object period and pulse width
<> 144:ef7eb2e8f9f7 82 obj->period = -1;
<> 144:ef7eb2e8f9f7 83 obj->pulse_width = -1;
<> 144:ef7eb2e8f9f7 84
<> 144:ef7eb2e8f9f7 85 // Disable the output
<> 144:ef7eb2e8f9f7 86 obj->pwm->train = 0x0;
<> 144:ef7eb2e8f9f7 87 obj->pwm->rate_length = 0x0;
<> 144:ef7eb2e8f9f7 88
<> 144:ef7eb2e8f9f7 89 // Configure the pin
<> 144:ef7eb2e8f9f7 90 pin_mode(pin, (PinMode)PullNone);
<> 144:ef7eb2e8f9f7 91 pin_function(pin, pwm.function);
<> 144:ef7eb2e8f9f7 92
<> 144:ef7eb2e8f9f7 93 // default to 20ms: standard for servos, and fine for e.g. brightness control
<> 144:ef7eb2e8f9f7 94 pwmout_period_us(obj, 20000);
<> 144:ef7eb2e8f9f7 95 pwmout_write (obj, 0);
<> 144:ef7eb2e8f9f7 96
<> 144:ef7eb2e8f9f7 97 // Set the drive mode to normal
<> 144:ef7eb2e8f9f7 98 MXC_SET_FIELD(&MXC_GPIO->out_mode[port], (0x7 << (port_pin*4)), (MXC_V_GPIO_OUT_MODE_NORMAL << (port_pin*4)));
<> 144:ef7eb2e8f9f7 99
<> 144:ef7eb2e8f9f7 100 // Enable this PWM channel
<> 144:ef7eb2e8f9f7 101 MXC_PTG->enable |= (1 << MXC_PT_GET_IDX(obj->pwm));
<> 144:ef7eb2e8f9f7 102 }
<> 144:ef7eb2e8f9f7 103
<> 144:ef7eb2e8f9f7 104 //******************************************************************************
<> 144:ef7eb2e8f9f7 105 void pwmout_free(pwmout_t* obj)
<> 144:ef7eb2e8f9f7 106 {
<> 144:ef7eb2e8f9f7 107 // Set the registers to the reset value
<> 144:ef7eb2e8f9f7 108 obj->pwm->train = 0;
<> 144:ef7eb2e8f9f7 109 obj->pwm->rate_length = 0x08000000;
<> 144:ef7eb2e8f9f7 110 }
<> 144:ef7eb2e8f9f7 111
<> 144:ef7eb2e8f9f7 112 //******************************************************************************
<> 144:ef7eb2e8f9f7 113 static void pwmout_update(pwmout_t* obj)
<> 144:ef7eb2e8f9f7 114 {
<> 144:ef7eb2e8f9f7 115 // Calculate and set the divider ratio
<> 144:ef7eb2e8f9f7 116 int div = (obj->period * (SystemCoreClock/1000000))/32;
<> 144:ef7eb2e8f9f7 117 if (div < 2){
<> 144:ef7eb2e8f9f7 118 div = 2;
<> 144:ef7eb2e8f9f7 119 }
<> 144:ef7eb2e8f9f7 120 MXC_SET_FIELD(&obj->pwm->rate_length, MXC_F_PT_RATE_LENGTH_RATE_CONTROL, div);
<> 144:ef7eb2e8f9f7 121
<> 144:ef7eb2e8f9f7 122 // Change the duty cycle to adjust the pulse width
<> 144:ef7eb2e8f9f7 123 obj->pwm->train = (0xFFFFFFFF << (32-((32*obj->pulse_width)/obj->period)));
<> 144:ef7eb2e8f9f7 124 }
<> 144:ef7eb2e8f9f7 125
<> 144:ef7eb2e8f9f7 126
<> 144:ef7eb2e8f9f7 127 //******************************************************************************
<> 144:ef7eb2e8f9f7 128 void pwmout_write(pwmout_t* obj, float percent)
<> 144:ef7eb2e8f9f7 129 {
<> 144:ef7eb2e8f9f7 130 // Saturate percent if outside of range
<> 144:ef7eb2e8f9f7 131 if (percent < 0.0f) {
<> 144:ef7eb2e8f9f7 132 percent = 0.0f;
<> 144:ef7eb2e8f9f7 133 } else if(percent > 1.0f) {
<> 144:ef7eb2e8f9f7 134 percent = 1.0f;
<> 144:ef7eb2e8f9f7 135 }
<> 144:ef7eb2e8f9f7 136
<> 144:ef7eb2e8f9f7 137 // Resize the pulse width to set the duty cycle
<> 144:ef7eb2e8f9f7 138 pwmout_pulsewidth_us(obj, (int)(percent*obj->period));
<> 144:ef7eb2e8f9f7 139 }
<> 144:ef7eb2e8f9f7 140
<> 144:ef7eb2e8f9f7 141 //******************************************************************************
<> 144:ef7eb2e8f9f7 142 float pwmout_read(pwmout_t* obj)
<> 144:ef7eb2e8f9f7 143 {
<> 144:ef7eb2e8f9f7 144 // Check for when pulsewidth or period equals 0
<> 144:ef7eb2e8f9f7 145 if ((obj->pulse_width == 0) || (obj->period == 0)){
<> 144:ef7eb2e8f9f7 146 return 0;
<> 144:ef7eb2e8f9f7 147 }
<> 144:ef7eb2e8f9f7 148
<> 144:ef7eb2e8f9f7 149 // Return the duty cycle
<> 144:ef7eb2e8f9f7 150 return ((float)obj->pulse_width / (float)obj->period);
<> 144:ef7eb2e8f9f7 151 }
<> 144:ef7eb2e8f9f7 152
<> 144:ef7eb2e8f9f7 153 //******************************************************************************
<> 144:ef7eb2e8f9f7 154 void pwmout_period(pwmout_t* obj, float seconds)
<> 144:ef7eb2e8f9f7 155 {
<> 144:ef7eb2e8f9f7 156 pwmout_period_us(obj, (int)(seconds * 1000000.0f));
<> 144:ef7eb2e8f9f7 157 }
<> 144:ef7eb2e8f9f7 158
<> 144:ef7eb2e8f9f7 159 //******************************************************************************
<> 144:ef7eb2e8f9f7 160 void pwmout_period_ms(pwmout_t* obj, int ms)
<> 144:ef7eb2e8f9f7 161 {
<> 144:ef7eb2e8f9f7 162 pwmout_period_us(obj, ms*1000);
<> 144:ef7eb2e8f9f7 163 }
<> 144:ef7eb2e8f9f7 164
<> 144:ef7eb2e8f9f7 165 //******************************************************************************
<> 144:ef7eb2e8f9f7 166 void pwmout_period_us(pwmout_t* obj, int us)
<> 144:ef7eb2e8f9f7 167 {
<> 144:ef7eb2e8f9f7 168 // Check the range of the period
<> 144:ef7eb2e8f9f7 169 MBED_ASSERT((us >= 0) && (us <= (int)(SystemCoreClock/32)));
<> 144:ef7eb2e8f9f7 170
<> 144:ef7eb2e8f9f7 171 // Set pulse width to half the period if uninitialized
<> 144:ef7eb2e8f9f7 172 if (obj->pulse_width == -1) {
<> 144:ef7eb2e8f9f7 173 obj->pulse_width = us/2;
<> 144:ef7eb2e8f9f7 174 }
<> 144:ef7eb2e8f9f7 175
<> 144:ef7eb2e8f9f7 176 // Save the period
<> 144:ef7eb2e8f9f7 177 obj->period = us;
<> 144:ef7eb2e8f9f7 178
<> 144:ef7eb2e8f9f7 179 // Update the registers
<> 144:ef7eb2e8f9f7 180 pwmout_update(obj);
<> 144:ef7eb2e8f9f7 181 }
<> 144:ef7eb2e8f9f7 182
<> 144:ef7eb2e8f9f7 183 //******************************************************************************
<> 144:ef7eb2e8f9f7 184 void pwmout_pulsewidth(pwmout_t* obj, float seconds)
<> 144:ef7eb2e8f9f7 185 {
<> 144:ef7eb2e8f9f7 186 pwmout_pulsewidth_us(obj, (int)(seconds * 1000000.0f));
<> 144:ef7eb2e8f9f7 187 }
<> 144:ef7eb2e8f9f7 188
<> 144:ef7eb2e8f9f7 189 //******************************************************************************
<> 144:ef7eb2e8f9f7 190 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms)
<> 144:ef7eb2e8f9f7 191 {
<> 144:ef7eb2e8f9f7 192 pwmout_pulsewidth_us(obj, ms*1000);
<> 144:ef7eb2e8f9f7 193 }
<> 144:ef7eb2e8f9f7 194
<> 144:ef7eb2e8f9f7 195 //******************************************************************************
<> 144:ef7eb2e8f9f7 196 void pwmout_pulsewidth_us(pwmout_t* obj, int us)
<> 144:ef7eb2e8f9f7 197 {
<> 144:ef7eb2e8f9f7 198 // Check the range of the pulsewidth
<> 144:ef7eb2e8f9f7 199 MBED_ASSERT((us >= 0) && (us <= (int)(SystemCoreClock/32)));
<> 144:ef7eb2e8f9f7 200
<> 144:ef7eb2e8f9f7 201 // Initialize period to double the pulsewidth if uninitialized
<> 144:ef7eb2e8f9f7 202 if (obj->period == -1) {
<> 144:ef7eb2e8f9f7 203 obj->period = 2*us;
<> 144:ef7eb2e8f9f7 204 }
<> 144:ef7eb2e8f9f7 205
<> 144:ef7eb2e8f9f7 206 // Save the pulsewidth
<> 144:ef7eb2e8f9f7 207 obj->pulse_width = us;
<> 144:ef7eb2e8f9f7 208
<> 144:ef7eb2e8f9f7 209 // Update the register
<> 144:ef7eb2e8f9f7 210 pwmout_update(obj);
<> 144:ef7eb2e8f9f7 211 }