PWM

First draft at PWM driver. Needs testing, then merging into GRBL.

smoother/pwm_driver.cpp

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+// PWM Driver - LPC176x - Single edge only, does not support double edge PWM
+//
+// Copyright 2017 Brett Fleming
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+#include "pwm_driver.h"
+#include "LPC17xx.h"
+
+#include "grbl.h"
+
+//LPC_PWM1_BASE
+//LPC_PWM1 is of type LPC_PWM_TypeDef at Address LPC_PWM1_BASE
+
+/*
+    Theory of operation: Initialize, start running, change width any time while running.
+
+    pwm_init(PWM1_CH1, 1000, 0);
+    pwm_enable(PWM1_CH1);
+    pwm_set_width(250);
+    sleep(1)
+    pwm_set_width(500);
+    sleep(1)
+    pwm_set_width(999);
+    sleep(1)
+    pwm_disable(PWM1_CH1);
+*/
+
+
+const PWM_Channel_Config PWM1_CH1 = {
+    &(LPC_PWM1->MR1),   //Match Register
+    (1 << 9),           //PWM Enable
+    (1 << 1)            //Latch Enable Register
+};
+
+const PWM_Channel_Config PWM1_CH2 = {
+    &(LPC_PWM1->MR2),   //Match Register
+    (1 << 10),          //PWM Enable
+    (1 << 2)            //Latch Enable Register
+};
+
+const PWM_Channel_Config PWM1_CH3 = {
+    &(LPC_PWM1->MR3),   //Match Register
+    (1 << 11),          //PWM Enable
+    (1 << 3)            //Latch Enable Register
+};
+
+const PWM_Channel_Config PWM1_CH4 = {
+    &(LPC_PWM1->MR4),   //Match Register
+    (1 << 12),          //PWM Enable
+    (1 << 4)            //Latch Enable Register
+};
+
+const PWM_Channel_Config PWM1_CH5 = {
+    &(LPC_PWM1->MR5),   //Match Register
+    (1 << 13),          //PWM Enable
+    (1 << 5)            //Latch Enable Register
+};
+
+const PWM_Channel_Config PWM1_CH6 = {
+    &(LPC_PWM1->MR6),   //Match Register
+    (1 << 14),          //PWM Enable
+    (1 << 6)            //Latch Enable Register
+};
+
+
+
+
+//Smoothie board uses P2.4 and P2.5 as PWM outputs
+
+//UM10360 LPC17xx Chapter 24 - Pulse Width Modulation
+
+//
+// channel - Which of the 6 PWM channels to init.
+// period - what is the overall period, in PCLK cycles, for ALL PWMs (not just the provided one)
+//
+void pwm_init(PWM_Channel_Config* channel, uint32_t period, uint32_t width) {
+    //Power up PCONP
+
+    //Match Control - Continous operation (no interrupts, no timer reset)
+    LPC_PWM1->MCR = 0x0000;
+
+    //PWM Control Register - Single Edge (0 for bits 2-6) mode for all PWMs
+    LPC_PWM1->PCR &= 0xFF00;
+    
+    //PWM Control Register - Disable output for channel
+    LPC_PWM1->PCR &= ~channel->PCR_Enable_Mask;
+
+    //Disable Capture
+    LPC_PWM1->CCR = 0x0000;
+
+    //PWM Timer Control Register - Counter Enable, PWM Enable
+    LPC_PWM1->TCR = (1 << 0) | (1 << 3);
+
+    //PWM Counter Control Register - Use Timer Mode (Counter Mode is for external clocks, not PWM)
+    LPC_PWM1->CTCR = 0x0000;
+
+    pwm_set_period(period);
+    pwm_set_width(channel, width);
+}
+
+void pwm_set_period(uint32_t period) {
+    LPC_PWM1->MR0 = period;
+
+    //If we are running, this will make the MRx register on the next cycle
+    LPC_PWM1->LER = (1 << 0);
+}
+
+void pwm_set_width(PWM_Channel_Config* channel, uint32_t width) {
+    *(channel->MRn) = width;
+
+    //If we are running, this will make the MRx register on the next cycle
+    LPC_PWM1->LER |= channel->LER_Enable_Mask;
+}
+
+void pwm_enable(PWM_Channel_Config* channel) {
+    //PWM Control Register - Enable output for channel
+    LPC_PWM1->PCR |= channel->PCR_Enable_Mask;
+}
+
+void pwm_disable(PWM_Channel_Config* channel) {
+    //PWM Control Register - Disable output for channel
+    LPC_PWM1->PCR &= ~channel->PCR_Enable_Mask;
+}
+

smoother/pwm_driver.h

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+// PWM Driver - LPC176x
+//
+// Copyright 2017 Brett Fleming
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+#include <stdint.h>
+
+typedef struct _PWM_Channel_Config {
+    volatile uint32_t* MRn; //LPC_PWM1->MR1 through MR6
+    uint32_t PCR_Enable_Mask;
+    uint32_t LER_Enable_Mask;
+} PWM_Channel_Config;
+
+extern const PWM_Channel_Config PWM1_CH1;
+
+void pwm_init(PWM_Channel_Config* channel, uint32_t period, uint32_t width);
+void pwm_set_period(uint32_t period);
+void pwm_set_width(PWM_Channel_Config* channel, uint32_t width);
+void pwm_enable(PWM_Channel_Config* channel);
+void pwm_disable(PWM_Channel_Config* channel);
+