Initial HW PWM (Delta-Sigma) (#609)

extras/dsm/component.mk

@@ -0,0 +1,9 @@
+# Component makefile for extras/dsm
+
+INC_DIRS += $(ROOT)extras/dsm
+
+# args for passing into compile rule generation
+extras/dsm_INC_DIR =  $(ROOT)extras/dsm
+extras/dsm_SRC_DIR =  $(ROOT)extras/dsm
+
+$(eval $(call component_compile_rules,extras/dsm))

extras/dsm/dsm.c

@@ -0,0 +1,111 @@
+/* Implementation of Delta-Sigma modulator support.
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2018 ourairquality (https://github.com/ourairquality)
+ * Copyright (C) 2018 Zaltora (https://github.com/Zaltora)
+ * BSD Licensed as described in the file LICENSE
+ */
+#include "dsm.h"
+
+#include <espressif/esp_common.h>
+#include <esp8266.h>
+
+
+#if (DSM_DEBUG)
+#define debug(fmt, ...) printf("%s: " fmt "\n", "DSM", ## __VA_ARGS__)
+#else
+#define debug(fmt, ...)
+#endif
+
+typedef struct dsmInfoDefinition
+{
+    uint8_t running;
+    uint8_t preScale;
+    uint8_t target;
+    bool output;
+
+    /* private */
+    uint8_t usedPins;
+    uint8_t pins[8];
+} DSMInfo;
+
+static DSMInfo dsmInfo;
+
+void dsm_init(uint8_t npins, const uint8_t* pins)
+{
+    /* Assert number of pins is correct */
+    if (npins > MAX_DSM_PINS)
+    {
+        debug("Incorrect number of DSM pins (%d)\n", npins);
+        return;
+    }
+
+    /* Save pins information */
+    dsmInfo.usedPins = npins;
+
+    for (uint8_t i = 0 ; i < npins; ++i)
+    {
+        dsmInfo.pins[i] = pins[i];
+        /* configure GPIOs */
+        gpio_enable(pins[i], GPIO_OUTPUT);
+    }
+
+    /* Set output to LOW */
+    dsm_stop();
+
+    /* Flag not running */
+    dsmInfo.running = 0;
+}
+
+void dsm_set_prescale(uint8_t prescale)
+{
+    //TODO: Add a freq/prescale converter
+    dsmInfo.preScale = prescale;
+    debug("Set Prescale: %u",dsmInfo.preScale);
+}
+
+void dsm_set_target(uint8_t target)
+{
+    dsmInfo.target = target;
+    if (target == 0 || target == UINT8_MAX)
+    {
+      dsmInfo.output = (target == UINT8_MAX);
+    }
+    debug("Duty set at %u",dsmInfo.target);
+    if (dsmInfo.running)
+    {
+        dsm_start();
+    }
+}
+
+void dsm_start()
+{
+    if (dsmInfo.target > 0 && dsmInfo.target < UINT8_MAX)
+    {
+        for (uint8_t i = 0; i < dsmInfo.usedPins; ++i)
+        {
+            SET_MASK_BITS(GPIO.CONF[dsmInfo.pins[i]], GPIO_CONF_SOURCE_DSM);
+        }
+        GPIO.DSM = GPIO_DSM_ENABLE | (dsmInfo.preScale << 8) | dsmInfo.target;
+    }
+    else
+    {
+      for (uint8_t i = 0; i < dsmInfo.usedPins; ++i)
+      {
+        gpio_write(dsmInfo.pins[i], dsmInfo.output );
+      }       
+    }
+    debug("start");
+    dsmInfo.running = 1;
+}
+
+void dsm_stop()
+{
+    for (uint8_t i = 0; i < dsmInfo.usedPins; ++i)
+    {
+      CLEAR_MASK_BITS(GPIO.CONF[dsmInfo.pins[i]], GPIO_CONF_SOURCE_DSM);
+      gpio_write(dsmInfo.pins[i], false);
+    }       
+    debug("stop");
+    dsmInfo.running = 0;
+}

extras/dsm/dsm.h

@@ -0,0 +1,36 @@
+/* Implementation of Delta-Sigma modulator support.
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2018 ourairquality (https://github.com/ourairquality)
+ * Copyright (C) 2018 Zaltora (https://github.com/Zaltora)
+ * BSD Licensed as described in the file LICENSE
+ */
+#ifndef EXTRAS_DSM_H_
+#define EXTRAS_DSM_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+#define MAX_DSM_PINS    (8)
+#define DSM_DEBUG       (0)
+
+/*
+ * Freq = (80,000,000/prescale) * (target / 256) HZ           (0   < target < 128)
+ * Freq = (80,000,000/prescale) * ((256 - target) / 256)  HZ  (128 < target < 256)
+ */
+
+void dsm_init(uint8_t npins, const uint8_t* pins);
+void dsm_set_prescale(uint8_t prescale);
+void dsm_set_target(uint8_t target);
+
+void dsm_start();
+void dsm_stop();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* EXTRAS_DSM_H_ */