Hardware timer support

core/esp_timer.c

@@ -0,0 +1,35 @@
+/* Timer peripheral management functions for esp/timer.h.
+ *
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2015 Superhouse Automation Pty Ltd
+ * BSD Licensed as described in the file LICENSE
+ */
+#include <esp/timer.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+ * These are the runtime implementations for functions that are linked in if any of
+ * the arguments aren't known at compile time (values are evaluated at
+ * compile time otherwise.)
+ */
+uint32_t _timer_freq_to_count_runtime(const timer_frc_t frc, const uint32_t freq, const timer_div_t div)
+{
+    return _timer_freq_to_count_impl(frc, freq, div);
+}
+
+uint32_t _timer_time_to_count_runtime(const timer_frc_t frc, uint32_t us, const timer_div_t div)
+{
+    return _timer_time_to_count_runtime(frc, us, div);
+}
+
+bool _timer_set_frequency_runtime(const timer_frc_t frc, uint32_t freq)
+{
+    return _timer_set_frequency_runtime(frc, freq);
+}
+
+bool _timer_set_timeout_runtime(const timer_frc_t frc, uint32_t us)
+{
+    return _timer_set_timeout_impl(frc, us);
+}

core/include/esp/gpio.h

@@ -117,6 +117,8 @@ typedef enum {
 extern void gpio_interrupt_handler(void);
 
 /* Set the interrupt type for a given pin
+ *
+ * If int_type is not INT_NONE, the gpio_interrupt_handler will be attached and unmasked.
  */
 INLINED void gpio_set_interrupt(const uint8_t gpio_num, const gpio_interrupt_t int_type)
 {
@@ -128,4 +130,10 @@ INLINED void gpio_set_interrupt(const uint8_t gpio_num, const gpio_interrupt_t i
     }
 }
 
+/* Return the interrupt type set for a pin */
+INLINED gpio_interrupt_t gpio_get_interrupt(const uint8_t gpio_num)
+{
+    return (gpio_interrupt_t)(GPIO_CTRL_REG(gpio_num) & GPIO_INT_MASK);
+}
+
 #endif

core/include/esp/registers.h

@@ -159,15 +159,17 @@ typedef volatile uint32_t *esp_reg_t;
 
 /* Load value for FRC1, read/write.
 
-   When TIMER_CTRL_RELOAD is cleared in TIMER_FRC1_CTRL_REG, FRC1
-   will reload to 0x7fffff once overflowed (unless the load value is
-   rewritten in the interrupt handler.)
+   When TIMER_CTRL_RELOAD is cleared in TIMER_FRC1_CTRL_REG, FRC1 will
+   reload to TIMER_FRC1_MAX_LOAD once overflowed (unless the load
+   value is rewritten in the interrupt handler.)
 
    When TIMER_CTRL_RELOAD is set in TIMER_FRC1_CTRL_REG, FRC1 will reload
    from the load register value once overflowed.
 */
 #define TIMER_FRC1_LOAD_REG   _REG(TIMER_BASE, 0x00)
 
+#define TIMER_FRC1_MAX_LOAD 0x7fffff
+
 /* Current count value for FRC1, read only? */
 #define TIMER_FRC1_COUNT_REG  _REG(TIMER_BASE, 0x04)
 
@@ -254,7 +256,7 @@ typedef volatile uint32_t *esp_reg_t;
 
 /* Timer auto-reload bit
 
-   This bit interacts with TIMER_FCR1_LOAD_REG & TIMER_FCR2_LOAD_REG
+   This bit interacts with TIMER_FRC1_LOAD_REG & TIMER_FRC2_LOAD_REG
    differently, see those registers for details.
 */
 #define TIMER_CTRL_RELOAD BIT(6)

core/include/esp/timer.h

@@ -0,0 +1,138 @@
+/** esp/timer.h
+ *
+ * Timer (FRC1 & FRC2) functions.
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2015 Superhouse Automation Pty Ltd
+ * BSD Licensed as described in the file LICENSE
+ */
+#ifndef _ESP_TIMER_H
+#define _ESP_TIMER_H
+
+#include <stdbool.h>
+#include <xtensa_interrupts.h>
+#include "esp/registers.h"
+#include "esp/cpu.h"
+
+typedef enum {
+    TIMER_FRC1,
+    TIMER_FRC2,
+} timer_frc_t;
+
+/* Return current count value for timer. */
+INLINED uint32_t timer_get_count(const timer_frc_t frc);
+
+/* Return current load value for timer. */
+INLINED uint32_t timer_get_load(const timer_frc_t frc);
+
+/* Write load value for timer. */
+INLINED void timer_set_load(const timer_frc_t frc, const uint32_t load);
+
+/* Returns maximum load value for timer. */
+INLINED uint32_t timer_max_load(const timer_frc_t frc);
+
+typedef enum {
+    TIMER_DIV1,
+    TIMER_DIV16,
+    TIMER_DIV256,
+} timer_div_t;
+
+/* Set the timer divider value */
+INLINED void timer_set_divider(const timer_frc_t frc, const timer_div_t div);
+
+/* Enable or disable timer interrupts
+
+   This both sets the xtensa interrupt mask and writes to the DPORT register
+   that allows timer interrupts.
+*/
+INLINED void timer_set_interrupts(const timer_frc_t frc, bool enable);
+
+/* Turn the timer on or off */
+INLINED void timer_set_run(const timer_frc_t frc, const bool run);
+
+/* Get the run state of the timer (on or off) */
+INLINED bool timer_get_run(const timer_frc_t frc);
+
+/* Set timer auto-reload on or off */
+INLINED void timer_set_reload(const timer_frc_t frc, const bool reload);
+
+/* Get the auto-reload state of the timer (on or off) */
+INLINED bool timer_get_reload(const timer_frc_t frc);
+
+/* Return a suitable timer divider for the specified frequency,
+   or -1 if none is found.
+ */
+INLINED timer_div_t timer_freq_to_div(uint32_t freq);
+
+/* Return the number of timer counts to achieve the specified
+ * frequency with the specified divisor.
+ *
+ * frc parameter is used to check out-of-range values for timer size.
+ *
+ * Returns 0 if the given freq/divisor combo cannot be achieved.
+ *
+ * Compile-time evaluates if all arguments are available at compile time.
+ */
+INLINED uint32_t timer_freq_to_count(const timer_frc_t frc, uint32_t freq, const timer_div_t div);
+
+/* Return a suitable timer divider for the specified duration in
+   microseconds or -1 if none is found.
+ */
+INLINED timer_div_t timer_time_to_div(uint32_t us);
+
+/* Return the number of timer counts for the specified timer duration
+ * in microseconds, when using the specified divisor.
+ *
+ * frc paraemter is used to check out-of-range values for timer size.
+ *
+ * Returns 0 if the given time/divisor combo cannot be achieved.
+ *
+ * Compile-time evaluates if all arguments are available at compile time.
+ */
+INLINED uint32_t timer_time_to_count(const timer_frc_t frc, uint32_t us, const timer_div_t div);
+
+/* Set a target timer interrupt frequency in Hz.
+
+   For FRC1 this sets the timer load value and enables autoreload so
+   the interrupt will fire regularly with the target frequency.
+
+   For FRC2 this sets the timer match value so the next interrupt
+   comes in line with the target frequency. However this won't repeat
+   automatically, you have to call timer_set_frequency again when the
+   timer interrupt runs.
+
+   Will change the timer divisor value to suit the target frequency.
+
+   Does not start/stop the timer, you have to do this manually via
+   timer_set_run.
+
+   Returns true on success, false if given frequency could not be set.
+
+   Compile-time evaluates to simple register writes if all arguments
+   are available at compile time.
+*/
+INLINED bool timer_set_frequency(const timer_frc_t frc, uint32_t freq);
+
+/* Sets the timer for a oneshot interrupt in 'us' microseconds.
+
+   Will change the timer divisor value to suit the target time.
+
+   Does not change the autoreload setting.
+
+   For FRC2 this sets the timer match value relative to the current
+   load value.
+
+   Note that for a true "one shot" timeout with FRC1 then you need to
+   also disable FRC1 in the timer interrupt handler by calling
+   timer_set_run(TIMER_FRC1, false);
+
+   Returns true if the timeout was successfully set.
+
+   Compile-time evaluates to simple register writes if all arguments
+   are available at compile time.
+*/
+INLINED bool timer_set_timeout(const timer_frc_t frc, uint32_t us);
+
+#include "timer_private.h"
+
+#endif

core/include/esp/timer_private.h

@@ -0,0 +1,273 @@
+/* Private header parts of the timer API implementation
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2015 Superhouse Automation Pty Ltd
+ * BSD Licensed as described in the file LICENSE
+ */
+#ifndef _ESP_TIMER_PRIVATE_H
+#define _ESP_TIMER_PRIVATE_H
+
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* Timer divisor index to max frequency */
+#define _FREQ_DIV1  (80*1000*1000)
+#define _FREQ_DIV16 (5*1000*1000)
+#define _FREQ_DIV256 312500
+const static uint32_t IROM _TIMER_FREQS[] = { _FREQ_DIV1, _FREQ_DIV16, _FREQ_DIV256 };
+
+/* Timer divisor index to divisor value */
+const static uint32_t IROM _TIMER_DIV_VAL[] = { 1, 16, 256 };
+
+/* Timer divisor to mask value */
+const static uint32_t IROM _TIMER_DIV_REG[] = { TIMER_CTRL_DIV_1, TIMER_CTRL_DIV_16, TIMER_CTRL_DIV_256 };
+
+INLINED esp_reg_t _timer_ctrl_reg(const timer_frc_t frc)
+{
+    return (frc == TIMER_FRC1) ? &TIMER_FRC1_CTRL_REG : &TIMER_FRC2_CTRL_REG;
+}
+
+INLINED uint32_t timer_get_count(const timer_frc_t frc)
+{
+    return (frc == TIMER_FRC1) ? TIMER_FRC1_COUNT_REG : TIMER_FRC2_COUNT_REG;
+}
+
+INLINED uint32_t timer_get_load(const timer_frc_t frc)
+{
+    return (frc == TIMER_FRC1) ? TIMER_FRC1_LOAD_REG : TIMER_FRC2_LOAD_REG;
+}
+
+INLINED void timer_set_load(const timer_frc_t frc, const uint32_t load)
+{
+    if(frc == TIMER_FRC1)
+        TIMER_FRC1_LOAD_REG = load;
+    else
+        TIMER_FRC2_LOAD_REG = load;
+}
+
+INLINED uint32_t timer_max_load(const timer_frc_t frc)
+{
+    return (frc == TIMER_FRC1) ? TIMER_FRC1_MAX_LOAD : UINT32_MAX;
+}
+
+INLINED void timer_set_divider(const timer_frc_t frc, const timer_div_t div)
+{
+    if(div < TIMER_DIV1 || div > TIMER_DIV256)
+        return;
+    esp_reg_t ctrl = _timer_ctrl_reg(frc);
+    *ctrl = (*ctrl & ~TIMER_CTRL_DIV_MASK) | (_TIMER_DIV_REG[div] & TIMER_CTRL_DIV_MASK);
+}
+
+INLINED void timer_set_interrupts(const timer_frc_t frc, bool enable)
+{
+    const uint32_t dp_bit = (frc == TIMER_FRC1) ? INT_ENABLE_FRC1 : INT_ENABLE_FRC2;
+    const uint32_t int_mask = BIT((frc == TIMER_FRC1) ? INUM_TIMER_FRC1 : INUM_TIMER_FRC2);
+    if(enable) {
+        DP_INT_ENABLE_REG |= dp_bit;
+        _xt_isr_unmask(int_mask);
+    } else {
+        DP_INT_ENABLE_REG &= ~dp_bit;
+        _xt_isr_mask(int_mask);
+    }
+}
+
+INLINED void timer_set_run(const timer_frc_t frc, const bool run)
+{
+    esp_reg_t ctrl = _timer_ctrl_reg(frc);
+    if (run)
+        *ctrl |= TIMER_CTRL_RUN;
+    else
+        *ctrl &= ~TIMER_CTRL_RUN;
+}
+
+INLINED bool timer_get_run(const timer_frc_t frc)
+{
+    return *_timer_ctrl_reg(frc) & TIMER_CTRL_RUN;
+}
+
+INLINED void timer_set_reload(const timer_frc_t frc, const bool reload)
+{
+    esp_reg_t ctrl = _timer_ctrl_reg(frc);
+    if (reload)
+        *ctrl |= TIMER_CTRL_RELOAD;
+    else
+        *ctrl &= ~TIMER_CTRL_RELOAD;
+}
+
+INLINED bool timer_get_reload(const timer_frc_t frc)
+{
+    return *_timer_ctrl_reg(frc) & TIMER_CTRL_RELOAD;
+}
+
+INLINED timer_div_t timer_freq_to_div(uint32_t freq)
+{
+    /*
+      try to maintain resolution without risking overflows.
+      these values are a bit arbitrary at the moment! */
+    if(freq > 100*1000)
+        return TIMER_DIV1;
+    else if(freq > 100)
+        return TIMER_DIV16;
+    else
+        return TIMER_DIV256;
+}
+
+/* timer_timer_to_count implementation - inline if all args are constant, call normally otherwise */
+
+INLINED uint32_t _timer_freq_to_count_impl(const timer_frc_t frc, const uint32_t freq, const timer_div_t div)
+{
+    if(div < TIMER_DIV1 || div > TIMER_DIV256)
+        return 0; /* invalid divider */
+
+    if(freq > _TIMER_FREQS[div])
+        return 0; /* out of range for given divisor */
+
+    uint64_t counts = _TIMER_FREQS[div]/freq;
+    return counts;
+}
+
+uint32_t _timer_freq_to_count_runtime(const timer_frc_t frc, const uint32_t freq, const timer_div_t div);
+
+INLINED uint32_t timer_freq_to_count(const timer_frc_t frc, const uint32_t freq, const timer_div_t div)
+{
+    if(__builtin_constant_p(frc) && __builtin_constant_p(freq) && __builtin_constant_p(div))
+        return _timer_freq_to_count_impl(frc, freq, div);
+    else
+        return _timer_freq_to_count_runtime(frc, freq, div);
+}
+
+INLINED timer_div_t timer_time_to_div(uint32_t us)
+{
+    /*
+      try to maintain resolution without risking overflows. Similar to
+      timer_freq_to_div, these values are a bit arbitrary at the
+      moment! */
+    if(us < 1000)
+        return TIMER_DIV1;
+    else if(us < 10*1000)
+        return TIMER_DIV16;
+    else
+        return TIMER_DIV256;
+}
+
+/* timer_timer_to_count implementation - inline if all args are constant, call normally otherwise */
+
+INLINED uint32_t _timer_time_to_count_impl(const timer_frc_t frc, uint32_t us, const timer_div_t div)
+{
+    if(div < TIMER_DIV1 || div > TIMER_DIV256)
+        return 0; /* invalid divider */
+
+    const uint32_t TIMER_MAX = timer_max_load(frc);
+
+    if(div != TIMER_DIV256) /* timer tick in MHz */
+    {
+        /* timer is either 80MHz or 5MHz, so either 80 or 5 MHz counts per us */
+        const uint32_t counts_per_us = ((div == TIMER_DIV1) ? _FREQ_DIV1 : _FREQ_DIV16)/1000/1000;
+        if(us > TIMER_MAX/counts_per_us)
+            return 0; /* Multiplying us by mhz_per_count will overflow TIMER_MAX */
+        return us*counts_per_us;
+    }
+    else /* /256 divider, 312.5kHz freq so need to scale up */
+    {
+        /* derived from naive floating point equation that we can't use:
+        counts = (us/1000/1000)*_FREQ_DIV256;
+        counts = (us/2000)*(_FREQ_DIV256/500);
+        counts = us*(_FREQ_DIV256/500)/2000;
+        */
+        const uint32_t scalar = _FREQ_DIV256/500;
+        if(us > 1+UINT32_MAX/scalar)
+            return 0; /* Multiplying us by _FREQ_DIV256/500 will overflow uint32_t */
+
+        uint32_t counts = (us*scalar)/2000;
+        if(counts > TIMER_MAX)
+            return 0; /* counts value too high for timer type */
+        return counts;
+    }
+}
+
+uint32_t _timer_time_to_count_runtime(const timer_frc_t frc, uint32_t us, const timer_div_t div);
+
+INLINED uint32_t timer_time_to_count(const timer_frc_t frc, uint32_t us, const timer_div_t div)
+{
+    if(__builtin_constant_p(frc) && __builtin_constant_p(us) && __builtin_constant_p(div))
+        return _timer_time_to_count_impl(frc, us, div);
+    else
+        return _timer_time_to_count_runtime(frc, us, div);
+}
+
+/* timer_set_frequency implementation - inline if all args are constant, call normally otherwise */
+
+INLINED bool _timer_set_frequency_impl(const timer_frc_t frc, uint32_t freq)
+{
+    uint32_t counts = 0;
+    timer_div_t div = timer_freq_to_div(freq);
+
+    counts = timer_freq_to_count(frc, freq, div);
+    if(counts == 0)
+    {
+        printf("ABORT: No counter for timer %d frequency %d\r\n", frc, freq);
+        abort();
+    }
+
+    timer_set_divider(frc, div);
+    if(frc == TIMER_FRC1)
+    {
+        timer_set_load(frc, counts);
+        timer_set_reload(frc, true);
+    }
+    else /* FRC2 */
+    {
+        /* assume that if this overflows it'll wrap, so we'll get desired behaviour */
+        TIMER_FRC2_MATCH_REG = counts + TIMER_FRC2_COUNT_REG;
+    }
+    return true;
+}
+
+bool _timer_set_frequency_runtime(const timer_frc_t frc, uint32_t freq);
+
+INLINED bool timer_set_frequency(const timer_frc_t frc, uint32_t freq)
+{
+    if(__builtin_constant_p(frc) && __builtin_constant_p(freq))
+        return _timer_set_frequency_impl(frc, freq);
+    else
+        return _timer_set_frequency_runtime(frc, freq);
+}
+
+/* timer_set_timeout implementation - inline if all args are constant, call normally otherwise */
+
+INLINED bool _timer_set_timeout_impl(const timer_frc_t frc, uint32_t us)
+{
+    uint32_t counts = 0;
+    timer_div_t div = timer_time_to_div(us);
+
+    counts = timer_time_to_count(frc, us, div);
+    if(counts == 0)
+        return false; /* can't set frequency */
+
+    timer_set_divider(frc, div);
+    if(frc == TIMER_FRC1)
+    {
+        timer_set_load(frc, counts);
+    }
+    else /* FRC2 */
+    {
+        TIMER_FRC2_MATCH_REG = counts + TIMER_FRC2_COUNT_REG;
+    }
+
+    return true;
+}
+
+bool _timer_set_timeout_runtime(const timer_frc_t frc, uint32_t us);
+
+INLINED bool timer_set_timeout(const timer_frc_t frc, uint32_t us)
+{
+    if(__builtin_constant_p(frc) && __builtin_constant_p(us))
+        return _timer_set_timeout_impl(frc, us);
+    else
+        return _timer_set_timeout_runtime(frc, us);
+}
+
+
+
+#endif

core/include/esp8266.h

@@ -16,5 +16,6 @@
 #include "esp/cpu.h"
 #include "esp/iomux.h"
 #include "esp/gpio.h"
+#include "esp/timer.h"
 
 #endif

examples/blink_timers/Makefile

@@ -0,0 +1,2 @@
+PROGRAM=blink_timers
+include ../../common.mk

examples/blink_timers/blink_timers.c

@@ -0,0 +1,64 @@
+/* The "blink" example, but writing the LED from timer interrupts
+ *
+ * This sample code is in the public domain.
+ */
+#include "espressif/esp_common.h"
+#include "espressif/sdk_private.h"
+#include "FreeRTOS.h"
+#include "task.h"
+#include "esp8266.h"
+
+const int gpio_frc1 = 12;
+const int freq_frc1 = 1;
+
+const int gpio_frc2 = 14;
+const int freq_frc2 = 10;
+
+static volatile uint32_t frc1_count;
+static volatile uint32_t frc2_count;
+
+void frc1_interrupt_handler(void)
+{
+    frc1_count++;
+    gpio_toggle(gpio_frc1);
+}
+
+void frc2_interrupt_handler(void)
+{
+    /* FRC2 needs the match register updated on each timer interrupt */
+    timer_set_frequency(TIMER_FRC2, freq_frc2);
+    frc2_count++;
+    gpio_toggle(gpio_frc2);
+}
+
+void user_init(void)
+{
+    sdk_uart_div_modify(0, UART_CLK_FREQ / 115200);
+
+    /* configure GPIOs */
+    gpio_enable(gpio_frc1, GPIO_OUTPUT);
+    gpio_enable(gpio_frc2, GPIO_OUTPUT);
+    gpio_write(gpio_frc1, 1);
+
+    /* stop both timers and mask their interrupts as a precaution */
+    timer_set_interrupts(TIMER_FRC1, false);
+    timer_set_run(TIMER_FRC1, false);
+    timer_set_interrupts(TIMER_FRC2, false);
+    timer_set_run(TIMER_FRC2, false);
+
+    /* set up ISRs */
+    _xt_isr_attach(INUM_TIMER_FRC1, frc1_interrupt_handler);
+    _xt_isr_attach(INUM_TIMER_FRC2, frc2_interrupt_handler);
+
+    /* configure timer frequencies */
+    timer_set_frequency(TIMER_FRC1, freq_frc1);
+    timer_set_frequency(TIMER_FRC2, freq_frc2);
+
+    /* unmask interrupts and start timers */
+    timer_set_interrupts(TIMER_FRC1, true);
+    timer_set_run(TIMER_FRC1, true);
+    timer_set_interrupts(TIMER_FRC2, true);
+    timer_set_run(TIMER_FRC2, true);
+
+    gpio_write(gpio_frc1, 0);
+}