esp32/machine_timer: Add support for esp32 hardware timer.

Available via the machine.Timer() class.

The code provides access to the four hardware timers available
on the ESP32, where bit 1 refers to the timer group, and bit 0
refers to the timer index. It is supposed that virtual timers
could be built on top of this in Python.

Code lineage:

Timer() is based loosely on the version in esp8266, although the
implementation is differs significantly because of the change in
the underlying platform.

Author: ak15199

esp32/Makefile

@@ -119,6 +119,7 @@ SRC_C = \
 	esponewire.c \
 	modutime.c \
 	moduos.c \
+	machine_timer.c \
 	machine_pin.c \
 	machine_touchpad.c \
 	machine_adc.c \

esp32/machine_timer.c

@@ -0,0 +1,192 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * Development of the code in this file was sponsored by Microbric Pty Ltd
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2015 Damien P. George
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * 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>
+#include <stdio.h>
+
+#include "driver/timer.h"
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "modmachine.h"
+
+#define TIMER_INTR_SEL TIMER_INTR_LEVEL
+#define TIMER_DIVIDER  40000
+#define TIMER_SCALE    (TIMER_BASE_CLK / TIMER_DIVIDER)
+
+#define TIMER_FLAGS    0
+
+typedef struct _machine_timer_obj_t {
+    mp_obj_base_t base;
+    mp_uint_t group;
+    mp_uint_t index;
+
+    mp_uint_t repeat;
+    mp_uint_t period;
+
+    mp_obj_t callback;
+
+    intr_handle_t handle;
+} machine_timer_obj_t;
+
+const mp_obj_type_t machine_timer_type;
+
+STATIC esp_err_t check_esp_err(esp_err_t code) {
+    if (code) {
+        mp_raise_OSError(code);
+    }
+
+    return code;
+}
+
+STATIC void machine_timer_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_timer_obj_t *self = self_in;
+
+    timer_config_t config;
+    mp_printf(print, "Timer(%p; ", self);
+
+    timer_get_config(self->group, self->index, &config);
+
+    mp_printf(print, "alarm_en=%d, ", config.alarm_en);
+    mp_printf(print, "auto_reload=%d, ", config.auto_reload);
+    mp_printf(print, "counter_en=%d)", config.counter_en);
+}
+
+STATIC mp_obj_t machine_timer_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 1, 1, false);
+    machine_timer_obj_t *self = m_new_obj(machine_timer_obj_t);
+    self->base.type = &machine_timer_type;
+
+    self->group = (mp_obj_get_int(args[0]) >> 1) & 1;
+    self->index = mp_obj_get_int(args[0]) & 1;
+
+    return self;
+}
+
+STATIC void machine_timer_disable(machine_timer_obj_t *self) {
+    if (self->handle) {
+        timer_pause(self->group, self->index);
+        esp_intr_free(self->handle);
+        self->handle = NULL;
+    }
+}
+
+STATIC void machine_timer_isr(void *self_in) {
+    machine_timer_obj_t *self = self_in;
+    timg_dev_t *device = self->group ? &(TIMERG1) : &(TIMERG0);
+
+    device->hw_timer[self->index].update = 1;
+    if (self->index) {
+        device->int_clr_timers.t1 = 1;
+    } else {
+        device->int_clr_timers.t0 = 1;
+    }
+    device->hw_timer[self->index].config.alarm_en = self->repeat;
+
+    mp_sched_schedule(self->callback, self);
+}
+
+STATIC void machine_timer_enable(machine_timer_obj_t *self) {
+    timer_config_t config;
+    config.alarm_en = TIMER_ALARM_EN;
+    config.auto_reload = self->repeat;
+    config.counter_dir = TIMER_COUNT_UP;
+    config.divider = TIMER_DIVIDER;
+    config.intr_type = TIMER_INTR_LEVEL;
+    config.counter_en = TIMER_PAUSE;
+
+    check_esp_err(timer_init(self->group, self->index, &config));
+    check_esp_err(timer_set_counter_value(self->group, self->index, 0x00000000));
+    check_esp_err(timer_set_alarm_value(self->group, self->index, self->period));
+    check_esp_err(timer_enable_intr(self->group, self->index));
+    check_esp_err(timer_isr_register(self->group, self->index, machine_timer_isr, (void*)self, TIMER_FLAGS, &self->handle));
+    check_esp_err(timer_start(self->group, self->index));
+}
+
+STATIC mp_obj_t machine_timer_init_helper(machine_timer_obj_t *self, mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_period,       MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+        { MP_QSTR_mode,         MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1} },
+        { MP_QSTR_callback,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+    };
+
+    machine_timer_disable(self);
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Timer uses an 80MHz base clock, which is divided by the divider/scalar, we then convert to ms.
+    self->period = (args[0].u_int * TIMER_BASE_CLK) / (1000 * TIMER_DIVIDER);
+    self->repeat = args[1].u_int;
+    self->callback = args[2].u_obj;
+    self->handle = NULL;
+
+    machine_timer_enable(self);
+
+    return mp_const_none;
+}
+
+STATIC mp_obj_t machine_timer_deinit(mp_obj_t self_in) {
+    machine_timer_disable(self_in);
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_timer_deinit_obj, machine_timer_deinit);
+
+STATIC mp_obj_t machine_timer_init(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+    return machine_timer_init_helper(args[0], n_args - 1, args + 1, kw_args);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_timer_init_obj, 1, machine_timer_init);
+
+STATIC mp_obj_t machine_timer_value(mp_obj_t self_in) {
+    machine_timer_obj_t *self = self_in;
+    double result;
+
+    timer_get_counter_time_sec(self->group, self->index, &result);
+
+    return MP_OBJ_NEW_SMALL_INT((mp_uint_t)(result * 1000));  // value in ms
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_timer_value_obj, machine_timer_value);
+
+STATIC const mp_map_elem_t machine_timer_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___del__), (mp_obj_t)&machine_timer_deinit_obj },
+    { MP_ROM_QSTR(MP_QSTR_deinit), (mp_obj_t)&machine_timer_deinit_obj },
+    { MP_ROM_QSTR(MP_QSTR_init), (mp_obj_t)&machine_timer_init_obj },
+    { MP_ROM_QSTR(MP_QSTR_value), (mp_obj_t)&machine_timer_value_obj },
+    { MP_ROM_QSTR(MP_QSTR_ONE_SHOT), MP_ROM_INT(false) },
+    { MP_ROM_QSTR(MP_QSTR_PERIODIC), MP_ROM_INT(true) },
+};
+STATIC MP_DEFINE_CONST_DICT(machine_timer_locals_dict, machine_timer_locals_dict_table);
+
+const mp_obj_type_t machine_timer_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Timer,
+    .print = machine_timer_print,
+    .make_new = machine_timer_make_new,
+    .locals_dict = (mp_obj_t)&machine_timer_locals_dict,
+};

esp32/modmachine.c

@@ -113,6 +113,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_time_pulse_us), MP_ROM_PTR(&machine_time_pulse_us_obj) },
 
+    { MP_ROM_QSTR(MP_QSTR_Timer), MP_ROM_PTR(&machine_timer_type) },
     { MP_ROM_QSTR(MP_QSTR_Pin), MP_ROM_PTR(&machine_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_TouchPad), MP_ROM_PTR(&machine_touchpad_type) },
     { MP_ROM_QSTR(MP_QSTR_ADC), MP_ROM_PTR(&machine_adc_type) },

esp32/modmachine.h

@@ -3,6 +3,7 @@
 
 #include "py/obj.h"
 
+extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_touchpad_type;
 extern const mp_obj_type_t machine_adc_type;