NRF52 series PWM reimplementation for SDK 14.2

Driver uses new API in SDK 14.2

Author: Marcus Chang

targets/TARGET_NORDIC/TARGET_NRF5x/PeripheralPinsDefault.c

@@ -30,3 +30,10 @@ MBED_WEAK const PinMapI2C PinMap_I2C[1] = {
 MBED_WEAK const PinMapSPI PinMap_SPI[1] = {
     {NC, NC, NC, NC}
 };
+
+/* Default mapping between PWM pins and PWM instance.
+ * Can be overwritten by user.
+ */
+MBED_WEAK const PinMapPWM PinMap_PWM[1] = {
+    {NC, NC}
+};

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_NRF52/TARGET_MCU_NRF52832/config/sdk_config.h

@@ -2266,14 +2266,14 @@
 
 
 #ifndef PWM1_ENABLED
-#define PWM1_ENABLED 0
+#define PWM1_ENABLED 1
 #endif
 
 // <q> PWM2_ENABLED  - Enable PWM2 instance
 
 
 #ifndef PWM2_ENABLED
-#define PWM2_ENABLED 0
+#define PWM2_ENABLED 1
 #endif
 
 // <q> PWM3_ENABLED  - Enable PWM3 instance

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_NRF52/TARGET_MCU_NRF52840/config/sdk_config.h

@@ -2266,21 +2266,21 @@
 
 
 #ifndef PWM1_ENABLED
-#define PWM1_ENABLED 0
+#define PWM1_ENABLED 1
 #endif
 
 // <q> PWM2_ENABLED  - Enable PWM2 instance
 
 
 #ifndef PWM2_ENABLED
-#define PWM2_ENABLED 0
+#define PWM2_ENABLED 1
 #endif
 
 // <q> PWM3_ENABLED  - Enable PWM3 instance
 
 
 #ifndef PWM3_ENABLED
-#define PWM3_ENABLED 0
+#define PWM3_ENABLED 1
 #endif
 
 // </e>

targets/TARGET_NORDIC/TARGET_NRF5x/objects.h

@@ -44,6 +44,8 @@
 #include "PeripheralNames.h"
 #include "PinNames.h"
 
+#include "nrf_pwm.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -62,10 +64,12 @@ struct port_s {
 };
 
 struct pwmout_s {
-    PWMName pwm_name;
+    int instance;
     PinName pin;
-    uint8_t pwm_channel;
-    void *  pwm_struct;
+    nrf_pwm_values_common_t pulse;
+    uint16_t period;
+    float percent;
+    nrf_pwm_sequence_t sequence;
 };
 
 struct i2c_s {

targets/TARGET_NORDIC/TARGET_NRF5x/pinmap_ex.c

@@ -31,14 +31,28 @@
 /* Define number of instances */
 #define NORDIC_TWI_COUNT TWI_COUNT
 #define NORDIC_SPI_COUNT SPI_COUNT
+#define NORDIC_PWM_COUNT PWM_COUNT
 
 /* Define which instance to return when there are no free instances left.
  * The Mbed HAL API doesn't provide a way for signaling initialization errors
  * so we return the default value. Any instance conflicts must be handled
  * by the driver implementation.
  */
 #define DEFAULT_I2C_INSTANCE 0 // SPI counts down, choose instance furthest away
-#define DEFAULT_SPI_INSTANCE (SPI_COUNT - 1) // I2C counts up, choose instance furthers away
+#define DEFAULT_SPI_INSTANCE (NORDIC_SPI_COUNT - 1) // I2C counts up, choose instance furthers away
+#define DEFAULT_PWM_INSTANCE (NORDIC_PWM_COUNT - 1)
+
+
+/***
+ *       _____ _____ _____ ___   _____
+ *      / ____|  __ \_   _|__ \ / ____|
+ *     | (___ | |__) || |    ) | |
+ *      \___ \|  ___/ | |   / /| |
+ *      ____) | |    _| |_ / /_| |____
+ *     |_____/|_|   |_____|____|\_____|
+ *
+ *
+ */
 
 /* Internal data structure shared between SPI and I2C to keep track of allocated
  * instances. The data structure is shared to reflect the hardware sharing.
@@ -246,3 +260,108 @@ int pin_instance_spi(PinName mosi, PinName miso, PinName clk)
 
     return instance;
 }
+
+
+/***
+ *      _______          ____  __
+ *     |  __ \ \        / /  \/  |
+ *     | |__) \ \  /\  / /| \  / |
+ *     |  ___/ \ \/  \/ / | |\/| |
+ *     | |      \  /\  /  | |  | |
+ *     |_|       \/  \/   |_|  |_|
+ *
+ *
+ */
+
+/* Internal data structure to keep track of allocated instances.
+ */
+static PinName nordic_internal_pwm[NORDIC_PWM_COUNT] = {
+    NC,
+    NC,
+    NC,
+#if (NORDIC_PWM_COUNT == 4)
+    NC,
+#endif
+};
+
+/**
+ * Brief       Find hardware instance for the provided PWM pin.
+ *
+ *             The function will search the PeripheralPin map for a pre-allocated
+ *             assignment. If none is found the allocation map will be searched
+ *             to see if the same pins have been assigned an instance before.
+ *
+ *             If no assignement is found and there is an empty slot left in the
+ *             map, the pins are stored in the map and the hardware instance is
+ *             returned.
+ *
+ *             If no free instances are available, the default instance is returned.
+ *
+ * Parameter   pwm   pwm pin.
+ *
+ * Return      Hardware instance associated with provided pins.
+ */
+int pin_instance_pwm(PinName pwm)
+{
+    int instance = NC;
+
+    /* Search pin map for pre-allocated instance */
+    for (size_t index = 0; (PinMap_PWM[index].pwm != NC); index++) {
+
+        /* Compare pins to entry. */
+        if (PinMap_PWM[index].pwm == pwm) {
+
+            DEBUG_PRINTF("found: %d %d\r\n", pwm, PinMap_PWM[index].instance);
+
+            /* Instance found, save result. */
+            instance = PinMap_PWM[index].instance;
+
+            /* Lock out entry in map. */
+            nordic_internal_pwm[instance] = pwm;
+            break;
+        }
+    }
+
+    /* No instance was found in static map. */
+    if (instance == NC) {
+
+        /* Search dynamic map for entry. */
+        for (size_t index = 0; index < NORDIC_PWM_COUNT; index++) {
+
+            /* Pins match previous dynamic allocation, return instance. */
+            if (nordic_internal_pwm[index] == pwm) {
+
+                instance = index;
+                break;
+            }
+        }
+    }
+
+    /* No instance was found in dynamic map. */
+    if (instance == NC) {
+
+        /* Search dynamic map for empty slot. */
+        for (size_t index = 0; index < NORDIC_PWM_COUNT; index++) {
+
+            /* Empty slot found, reserve slot by storing pins. */
+            if (nordic_internal_pwm[index] == NC) {
+
+                nordic_internal_pwm[index] = pwm;
+
+                instance = index;
+                break;
+            }
+        }
+    }
+
+#if defined(DEFAULT_PWM_INSTANCE)
+    /* Exhausted all options. Return default value. */
+    if (instance == NC) {
+        instance = DEFAULT_PWM_INSTANCE;
+    }
+#endif
+
+    DEBUG_PRINTF("PWM: %d %d\r\n", pwm, instance);
+
+    return instance;
+}

targets/TARGET_NORDIC/TARGET_NRF5x/pinmap_ex.h

@@ -42,6 +42,14 @@ typedef struct {
 
 extern const PinMapSPI PinMap_SPI[];
 
+/* Data structure for pre-allocated PWM instances. */
+typedef struct {
+    PinName pwm;
+    int instance;
+} PinMapPWM;
+
+extern const PinMapPWM PinMap_PWM[];
+
 /**
  * @brief      Find hardware instance for the provided I2C pins.
  *
@@ -83,6 +91,25 @@ int pin_instance_i2c(PinName sda, PinName scl);
  */
 int pin_instance_spi(PinName mosi, PinName miso, PinName clk);
 
+/**
+ * @brief      Find hardware instance for the provided PWM pins.
+ *
+ *             The function will search the PeripheralPin map for a pre-allocated
+ *             assignment. If none is found the allocation map will be searched
+ *             to see if the same pins have been assigned an instance before.
+ *
+ *             If no assignement is found and there is an empty slot left in the
+ *             map, the pins are stored in the map and the hardware instance is
+ *             returned.
+ *
+ *             If no free instances are available, the default instance is returned.
+ *
+ * @param[in]  pwm    pwm pin.
+ *
+ * @return     Hardware instance associated with provided pins.
+ */
+int pin_instance_pwm(PinName pwm);
+
 #ifdef __cplusplus
 }
 #endif