initial support for PWM output

ATM, only on timer1/PB4, but more can be easily added (and will be) Signed-off-by: Marc <dkm@kataplop.net>
6 years ago · 9d4accfe1a
3 changed files with 319 additions and 0 deletions
--- a/boards/ek-lm4f120xl/Makefile.features
+++ b/boards/ek-lm4f120xl/Makefile.features
@ -2,6 +2,7 @@
 FEATURES_PROVIDED += periph_adc
 FEATURES_PROVIDED += periph_gpio
 FEATURES_PROVIDED += periph_spi
+FEATURES_PROVIDED += periph_pwm
 FEATURES_PROVIDED += periph_timer
 FEATURES_PROVIDED += periph_uart

--- a/cpu/lm4f120/include/periph_cpu.h
+++ b/cpu/lm4f120/include/periph_cpu.h
@ -89,6 +89,22 @@ enum {
  PORT_F = 5,       /**< port F */
 };

+/**
+ * @name PWM configuration
+ * @{
+ */
+#define PWM_NUMOF           (8)
+#define PWM_0_EN            1
+#define PWM_1_EN            1
+#define PWM_2_EN            1
+#define PWM_3_EN            1
+#define PWM_4_EN            1
+#define PWM_5_EN            1
+#define PWM_6_EN            1
+#define PWM_7_EN            1
+#define PWM_MAX_CHANNELS    1
+/** @} */
+
 /**
 * @brief   Override resolution options
 */
--- a/cpu/lm4f120/periph/pwm.c
+++ b/cpu/lm4f120/periph/pwm.c
@ -0,0 +1,302 @@
+/*
+ * Copyright (C) 2015 Marc Poulhiès
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup     cpu_lm4f120
+ * @{
+ *
+ * @file
+ * @brief       Low-level PWM driver implementation
+ *
+ * @author      Marc Poulhiès <dkm@kataplop.net>
+ *
+ * @}
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "log.h"
+#include "cpu.h"
+#include "board.h"
+#include "periph/pwm.h"
+#include "periph/gpio.h"
+#include "periph_conf.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+/* ignore file in case no PWM devices are defined */
+#if PWM_NUMOF
+
+typedef struct pwm_chan_s {
+    const unsigned long timer_sysctl;
+    const unsigned long timer_base;
+    const unsigned long gpio_sysctl;
+    const unsigned long gpio_port;
+    const uint8_t gpio_pin_num;
+    const unsigned long timer_cfg;
+    const unsigned long timer_side;
+    const unsigned long ccp;
+} pwm_dev_t;
+
+typedef struct pwm_settings_s {
+    unsigned long ticks;
+    unsigned long resolution;
+} pwm_settings_t;
+
+
+static pwm_settings_t pwm_settings[PWM_NUMOF];
+
+static const pwm_dev_t pwm_devs[PWM_NUMOF] = {
+    {               /* 0 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER0,
+        .timer_base = TIMER0_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_6,
+        .timer_side = TIMER_A,
+        .timer_cfg = TIMER_CFG_A_PWM,
+        .ccp = GPIO_PB6_T0CCP0,
+    },
+    {           /* 1 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER0,
+        .timer_base = TIMER0_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_7,
+        .timer_side = TIMER_B,
+        .timer_cfg = TIMER_CFG_B_PWM,
+        .ccp = GPIO_PB7_T0CCP1,
+    },
+    {           /* 2 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER1,
+        .timer_base = TIMER1_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_4,
+        .timer_cfg = TIMER_CFG_A_PWM,
+        .timer_side = TIMER_A,
+        .ccp = GPIO_PB4_T1CCP0,
+    },
+    {           /* 3 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER1,
+        .timer_base = TIMER1_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_5,
+        .timer_cfg = TIMER_CFG_B_PWM,
+        .timer_side = TIMER_B,
+        .ccp = GPIO_PB5_T1CCP1,
+    },
+
+    /* Other PWM that can be used, but current PWM interface only allows for 4 devices */
+    {           /* 4 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER2,
+        .timer_base = TIMER2_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_0,
+        .timer_cfg = TIMER_CFG_A_PWM,
+        .timer_side = TIMER_A,
+        .ccp = GPIO_PB0_T2CCP0,
+    },
+    {           /* 5 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER1,
+        .timer_base = TIMER1_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_1,
+        .timer_cfg = TIMER_CFG_B_PWM,
+        .timer_side = TIMER_B,
+        .ccp = GPIO_PB1_T2CCP1,
+    },
+    {           /* 6 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER2,
+        .timer_base = TIMER2_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_2,
+        .timer_cfg = TIMER_CFG_A_PWM,
+        .timer_side = TIMER_A,
+        .ccp = GPIO_PB2_T3CCP0,
+    },
+    {           /* 7 */
+        .timer_sysctl = SYSCTL_PERIPH_TIMER2,
+        .timer_base = TIMER2_BASE,
+        .gpio_sysctl = SYSCTL_PERIPH_GPIOB,
+        .gpio_port = GPIO_PORTB_BASE,
+        .gpio_pin_num = GPIO_PIN_3,
+        .timer_cfg = TIMER_CFG_B_PWM,
+        .timer_side = TIMER_B,
+        .ccp = GPIO_PB3_T3CCP1,
+    }
+};
+
+static void pwm_start(pwm_t dev)
+{
+    const unsigned long timer_base = pwm_devs[dev].timer_base;
+    const unsigned long timer_ab = pwm_devs[dev].timer_side;
+
+    ROM_TimerEnable(timer_base, timer_ab);
+}
+
+uint32_t pwm_init(pwm_t dev, pwm_mode_t mode,
+                  uint32_t frequency, uint16_t resolution)
+{
+    if (dev >= PWM_NUMOF) {
+        return -1;
+    }
+
+    pwm_poweron(dev);
+
+    const unsigned long timer_pwm_cfg = pwm_devs[dev].timer_cfg;
+    const unsigned long timer_base = pwm_devs[dev].timer_base;
+    const unsigned long gpio_pin = pwm_devs[dev].gpio_pin_num;
+    const unsigned long ccp = pwm_devs[dev].ccp;
+    const unsigned long timer_ab = pwm_devs[dev].timer_side;
+    const unsigned long gpio_sysctl = pwm_devs[dev].gpio_sysctl;
+    const unsigned long gpio_port_base = pwm_devs[dev].gpio_port;
+
+    ROM_SysCtlPeripheralEnable(gpio_sysctl);
+
+    ROM_GPIOPinConfigure(ccp);
+    ROM_GPIOPinTypePWM(gpio_port_base, gpio_pin);
+
+    ROM_TimerDisable(timer_base, timer_ab);
+    ROM_TimerConfigure(timer_base, TIMER_CFG_SPLIT_PAIR | timer_pwm_cfg);
+
+    const unsigned long clock = ROM_SysCtlClockGet();
+
+    const unsigned long ticks = clock / frequency;
+    const unsigned long real_freq = frequency;
+
+    pwm_settings[dev].resolution = resolution;
+    pwm_settings[dev].ticks = ticks;
+
+    unsigned long ticks_high = ticks >> 16;
+    unsigned long ticks_low  = ticks & 0xFFFF;
+
+    if (ticks_high & ~0xFF) {
+        DEBUG("Frequency too low\n");
+        return -1;
+    }
+
+    DEBUG("Prescaler/Load set at 0x%lx/0x%lx\n", ticks_high, ticks_low);
+
+    ROM_TimerPrescaleSet(timer_base, timer_ab, ticks_high);
+    ROM_TimerLoadSet(timer_base, timer_ab, ticks_low);
+
+    DEBUG("Setting ticks at %lu (reqf: %" PRIu32 ", freq cpu: %lu)\n", ticks, frequency, clock);
+    DEBUG("Real freq: %lu\n", real_freq);
+    DEBUG("Resolution: %" PRIu16 "\n", resolution);
+    ROM_TimerPrescaleMatchSet(timer_base, timer_ab, 0);
+    ROM_TimerMatchSet(timer_base, timer_ab, 0);
+
+    /* set PWM mode */
+    unsigned int level;
+    switch (mode) {
+        case PWM_LEFT:
+            level = 0;
+            break;
+        case PWM_RIGHT:
+            level = 1;
+            break;
+        case PWM_CENTER:
+        default:
+            return -1;
+    }
+    ROM_TimerControlLevel(timer_base, timer_ab, level);
+
+    pwm_start(dev);
+
+    return real_freq;
+}
+
+uint8_t pwm_channels(pwm_t dev) {
+  return 1;
+}
+
+static void dump_pwm(pwm_t dev, int channel){
+#if DEBUG_ENABLE
+    if (channel >= PWM_MAX_CHANNELS) {
+        return;
+    }
+
+    const unsigned long timer_base = pwm_devs[dev].timer_base;
+    const unsigned long timer_ab = pwm_devs[dev].timer_side;
+    const unsigned long ticks_low  = ROM_TimerLoadGet(timer_base, timer_ab);
+    const unsigned long ticks_high = ROM_TimerPrescaleGet(timer_base, timer_ab);
+    const unsigned long long ticks = (ticks_high << 16) | ticks_low;
+    const unsigned long duty_ticks_low  = ROM_TimerMatchGet(timer_base, timer_ab);
+    const unsigned long duty_ticks_high = ROM_TimerPrescaleMatchGet(timer_base, timer_ab);
+    const unsigned long long duty = (duty_ticks_high << 16) | duty_ticks_low;
+
+    DEBUG("MATCH Prescaler/Load set at 0x%lx/0x%lx\n", duty_ticks_high, duty_ticks_low);
+    DEBUG("LOAD Prescaler/Load set at 0x%lx/0x%lx\n", ticks_high, ticks_low);
+    DEBUG("LOAD duty cycle : %lu%%\n",
+          (unsigned long) ((unsigned long long)(ticks - duty) * 100ULL / ticks));
+#endif
+}
+
+
+void pwm_set(pwm_t dev, uint8_t channel, uint16_t value)
+{
+    if (channel >= PWM_MAX_CHANNELS) {
+        return;
+    }
+
+    const unsigned long timer_base = pwm_devs[dev].timer_base;
+    const unsigned long timer_ab = pwm_devs[dev].timer_side;
+
+    const unsigned long real_resolution = pwm_settings[dev].ticks;
+    const unsigned long requested_value = pwm_settings[dev].resolution - value;
+    const unsigned long requested_resolution = pwm_settings[dev].resolution;
+    /* scale value wrt resolution */
+    const unsigned long scaled_value = (real_resolution / requested_resolution) * requested_value;
+
+    DEBUG("Req resolution %lu\n", requested_resolution);
+    DEBUG("Req value %lu\n", requested_value);
+    DEBUG("Real resolution %lu\n", real_resolution);
+
+    DEBUG("Set, scaled (for %u) %lu\n", value, scaled_value);
+    const unsigned long ticks_high = (scaled_value & 0xFFFF0000) >> 16;
+    const unsigned long ticks_low  =  scaled_value & 0x0000FFFF;
+
+    dump_pwm(dev, channel);
+
+    ROM_TimerPrescaleMatchSet(timer_base, timer_ab, ticks_high);
+    ROM_TimerMatchSet(timer_base, timer_ab, ticks_low);
+
+    dump_pwm(dev, channel);
+}
+
+
+/* static  void pwm_stop(pwm_t dev) */
+/* { */
+/*     const unsigned long timer_base = pwm_devs[dev].timer_base; */
+/*     const unsigned long timer_ab = pwm_devs[dev].timer_side; */
+
+/*     ROM_TimerDisable(timer_base, timer_ab); */
+/* } */
+
+void pwm_poweron(pwm_t dev)
+{
+    const unsigned long timer_sysctl = pwm_devs[dev].timer_sysctl;
+
+    ROM_SysCtlPeripheralEnable(timer_sysctl);
+}
+
+void pwm_poweroff(pwm_t dev)
+{
+    const unsigned long timer_sysctl = pwm_devs[dev].timer_sysctl;
+
+    ROM_SysCtlPeripheralDisable(timer_sysctl);
+}
+
+#endif /* PWM_NUMOF */