cc3200: Add Timer module. Supports free running, PWM and capture modes.

1 files changed, 834 insertions, 0 deletions

diff --git a/cc3200/mods/pybtimer.c b/cc3200/mods/pybtimer.c
new file mode 100644
index 000000000..c52b50611
--- /dev/null
+++ b/cc3200/mods/pybtimer.c
@@ -0,0 +1,834 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Daniel Campora
+ *
+ * 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 <string.h>
+
+#include "py/mpconfig.h"
+#include MICROPY_HAL_H
+#include "py/obj.h"
+#include "py/nlr.h"
+#include "py/runtime.h"
+#include "py/gc.h"
+#include "inc/hw_types.h"
+#include "inc/hw_ints.h"
+#include "inc/hw_memmap.h"
+#include "inc/hw_timer.h"
+#include "rom_map.h"
+#include "interrupt.h"
+#include "prcm.h"
+#include "timer.h"
+#include "pybtimer.h"
+#include "pybsleep.h"
+#include "mpcallback.h"
+#include "mpexception.h"
+
+
+/// \moduleref pyb
+/// \class Timer - generate periodic events, count events, and create PWM signals.
+///
+/// Each timer consists of a counter that counts up at a certain rate.  The rate
+/// at which it counts is the peripheral clock frequency (in Hz) divided by the
+/// timer prescaler.  When the counter reaches the timer period it triggers an
+/// event, and the counter resets back to zero.  By using the callback method,
+/// the timer event can call a Python function.
+///
+/// Example usage to toggle an LED at a fixed frequency:
+///
+///     tim = pyb.Timer(3)                                              # create a timer object using timer 4
+///     tim.init(mode=Timer.PERIODIC)                                   # initialize it in periodic mode
+///     tim_ch = tim.channel(Timer.A, freq=2)                           # configure channel A at a frequency of 2Hz
+///     tim_ch.callback(handler=lambda t:led.toggle())                  # toggle a led on every cycle of the timer
+///
+/// Further examples:
+///
+///     tim1 = pyb.Timer(2, mode=Timer.EVENT_COUNT)                     # initialize it capture mode
+///     tim2 = pyb.Timer(0, mode=Timer.PWM)                             # initialize it in PWM mode
+///     tim_ch = tim1.channel(Timer.A, freq=1, polarity=Timer.POSITIVE) # start the PWM on channel B with a 50% duty cycle
+///     tim_ch = tim2.channel(Timer.B, freq=10000, duty_cycle=50)       # start the event counter with a frequency of 1Hz and triggered by positive edges
+///     tim_ch.time()                                                   # get the current time in usec (can also be set)
+///     tim_ch.freq(20)                                                 # set the frequency (can also get)
+///     tim_ch.duty_cycle(30)                                           # set the duty cycle to 30% (can also get)
+///     tim_ch.duty_cycle(30, Timer.NEGATIVE)                           # set the duty cycle to 30% and change the polarity to negative
+///     tim_ch.event_count()                                            # get the number of captured events
+///     tim_ch.event_time()                                             # get the the time of the last captured event
+///
+
+/******************************************************************************
+ DECLARE PRIVATE CONSTANTS
+ ******************************************************************************/
+#define PYBTIMER_NUM_TIMERS                         (4)
+#define PYBTIMER_POLARITY_POS                       (0x01)
+#define PYBTIMER_POLARITY_NEG                       (0x02)
+
+#define PYBTIMER_SRC_FREQ_HZ                        HAL_FCPU_HZ
+
+/******************************************************************************
+ DEFINE PRIVATE TYPES
+ ******************************************************************************/
+typedef struct _pyb_timer_obj_t {
+    mp_obj_base_t base;
+    uint32_t timer;
+    uint32_t config;
+    uint16_t intflags;
+    uint8_t peripheral;
+    uint8_t id;
+} pyb_timer_obj_t;
+
+typedef struct _pyb_timer_channel_obj_t {
+    mp_obj_base_t base;
+    struct _pyb_timer_obj_t *timer;
+    uint32_t frequency;
+    uint16_t channel;
+    uint8_t  polarity;
+    uint8_t  duty_cycle;
+} pyb_timer_channel_obj_t;
+
+/******************************************************************************
+ DEFINE PRIVATE DATA
+ ******************************************************************************/
+STATIC const mp_cb_methods_t pyb_timer_channel_cb_methods;
+STATIC pyb_timer_obj_t pyb_timer_obj[PYBTIMER_NUM_TIMERS] = {{.timer = TIMERA0_BASE, .peripheral = PRCM_TIMERA0},
+                                                             {.timer = TIMERA1_BASE, .peripheral = PRCM_TIMERA1},
+                                                             {.timer = TIMERA2_BASE, .peripheral = PRCM_TIMERA2},
+                                                             {.timer = TIMERA3_BASE, .peripheral = PRCM_TIMERA3}};
+STATIC const mp_obj_type_t pyb_timer_channel_type;
+
+/******************************************************************************
+ DECLARE PRIVATE FUNCTIONS
+ ******************************************************************************/
+STATIC mp_obj_t pyb_timer_channel_callback (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
+STATIC void timer_disable (pyb_timer_obj_t *tim);
+STATIC void TIMER0AIntHandler(void);
+STATIC void TIMER0BIntHandler(void);
+STATIC void TIMER1AIntHandler(void);
+STATIC void TIMER1BIntHandler(void);
+STATIC void TIMER2AIntHandler(void);
+STATIC void TIMER2BIntHandler(void);
+STATIC void TIMER3AIntHandler(void);
+STATIC void TIMER3BIntHandler(void);
+
+/******************************************************************************
+ DEFINE PUBLIC FUNCTIONS
+ ******************************************************************************/
+void timer_init0 (void) {
+    mp_obj_list_init(&MP_STATE_PORT(pyb_timer_channel_obj_list), 0);
+}
+
+void timer_disable_all (void) {
+    pyb_timer_obj_t timer = {
+            .timer = TIMERA0_BASE,
+            .intflags = TIMER_CAPB_EVENT   | TIMER_CAPB_MATCH |
+                        TIMER_TIMB_TIMEOUT | TIMER_CAPA_EVENT |
+                        TIMER_CAPA_MATCH   | TIMER_TIMA_TIMEOUT,
+            .peripheral = PRCM_TIMERA0
+    };
+
+    for (uint32_t i = 0; i < PYBTIMER_NUM_TIMERS; i++) {
+        // in case it's not clocked
+        MAP_PRCMPeripheralClkEnable(timer.peripheral, PRCM_RUN_MODE_CLK | PRCM_SLP_MODE_CLK);
+        timer_disable(&timer);
+        // timer base offset according to hw_memmap.h
+        timer.timer += 0x1000;
+        // peripheral offset according to prcm.h
+        timer.peripheral++;
+    }
+}
+
+void pyb_timer_channel_callback_enable (mp_obj_t self_in) {
+    pyb_timer_channel_obj_t *self = self_in;
+    MAP_TimerIntClear(self->timer->timer, self->timer->intflags & self->channel);
+    MAP_TimerIntEnable(self->timer->timer, self->timer->intflags & self->channel);
+}
+
+void pyb_timer_channel_callback_disable (mp_obj_t self_in) {
+    pyb_timer_channel_obj_t *self = self_in;
+    MAP_TimerIntDisable(self->timer->timer, self->timer->intflags & self->channel);
+}
+
+pyb_timer_channel_obj_t *pyb_timer_channel_find (uint32_t timer, uint16_t channel_n) {
+    for (mp_uint_t i = 0; i < MP_STATE_PORT(pyb_timer_channel_obj_list).len; i++) {
+        pyb_timer_channel_obj_t *ch = ((pyb_timer_channel_obj_t *)(MP_STATE_PORT(pyb_timer_channel_obj_list).items[i]));
+        // any 32-bit timer must be matched by any of its 16-bit versions
+        if (ch->timer->timer == timer && ((ch->channel & TIMER_A) == channel_n || (ch->channel & TIMER_B) == channel_n)) {
+            return ch;
+        }
+    }
+    return MP_OBJ_NULL;
+}
+
+void pyb_timer_channel_remove (pyb_timer_channel_obj_t *ch) {
+    pyb_timer_channel_obj_t *channel;
+    if ((channel = pyb_timer_channel_find(ch->timer->timer, ch->channel))) {
+        mp_obj_list_remove(&MP_STATE_PORT(pyb_timer_channel_obj_list), channel);
+    }
+}
+
+void pyb_timer_channel_add (pyb_timer_channel_obj_t *ch) {
+    // remove it in case it already exists
+    pyb_timer_channel_remove(ch);
+    mp_obj_list_append(&MP_STATE_PORT(pyb_timer_channel_obj_list), ch);
+}
+
+STATIC void timer_disable (pyb_timer_obj_t *tim) {
+    // disable all timers and it's interrupts
+    MAP_TimerDisable(tim->timer, TIMER_A | TIMER_B);
+    MAP_TimerIntDisable(tim->timer, tim->intflags);
+    MAP_TimerIntClear(tim->timer, tim->intflags);
+    MAP_PRCMPeripheralClkDisable(tim->peripheral, PRCM_RUN_MODE_CLK | PRCM_SLP_MODE_CLK);
+    memset(&pyb_timer_obj[tim->id], 0, sizeof(pyb_timer_obj_t));
+}
+
+// computes prescaler period and match value so timer triggers at freq-Hz
+STATIC uint32_t compute_prescaler_period_and_match_value(pyb_timer_channel_obj_t *ch, uint32_t *period_out, uint32_t *match_out) {
+    uint32_t maxcount = (ch->channel == (TIMER_A | TIMER_B)) ? 0xFFFFFFFF : 0xFFFF;
+    uint32_t prescaler;
+    uint32_t period = PYBTIMER_SRC_FREQ_HZ / ch->frequency;
+
+    period = MAX(1, period) - 1;
+    prescaler = period >> 16;
+    *period_out = period;
+    if (prescaler > 0xFF && maxcount == 0xFFFF) {
+        goto error;
+    }
+    // check limit values for the duty cycle
+    if (ch->duty_cycle == 0) {
+        *match_out = period - 1;
+    }
+    else {
+        *match_out = period - ((period * ch->duty_cycle) / 100);
+    }
+    if ((ch->timer->config & 0x0F) == TIMER_CFG_A_PWM && (*match_out > 0xFFFF)) {
+        goto error;
+    }
+    return prescaler;
+
+error:
+    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+}
+
+STATIC void timer_init (pyb_timer_obj_t *tim) {
+    MAP_PRCMPeripheralClkEnable(tim->peripheral, PRCM_RUN_MODE_CLK | PRCM_SLP_MODE_CLK);
+    MAP_PRCMPeripheralReset(tim->peripheral);
+    MAP_TimerConfigure(tim->timer, tim->config);
+}
+
+STATIC void timer_channel_init (pyb_timer_channel_obj_t *ch) {
+    // calculate the period, the prescaler and the match value
+    uint32_t period;
+    uint32_t match;
+    uint32_t prescaler = compute_prescaler_period_and_match_value(ch, &period, &match);
+
+    // set the prescaler
+    MAP_TimerPrescaleSet(ch->timer->timer, ch->channel, (prescaler < 0xFF) ? prescaler : 0);
+
+    // set the load value
+    MAP_TimerLoadSet(ch->timer->timer, ch->channel, period);
+
+    // configure the pwm if we are in such mode
+    if ((ch->timer->config & 0x0F) == TIMER_CFG_A_PWM) {
+        // invert the timer output if required
+        MAP_TimerControlLevel(ch->timer->timer, ch->channel, (ch->polarity == PYBTIMER_POLARITY_NEG) ? true : false);
+        // set the match value (which is simply the duty cycle translated to ticks)
+        MAP_TimerMatchSet(ch->timer->timer, ch->channel, match);
+    }
+    // configure the event edge type if we are in such mode
+    else if ((ch->timer->config & 0x0F) == TIMER_CFG_A_CAP_COUNT || (ch->timer->config & 0x0F) == TIMER_CFG_A_CAP_TIME) {
+        uint32_t polarity = TIMER_EVENT_BOTH_EDGES;
+        if (ch->polarity == PYBTIMER_POLARITY_POS) {
+            polarity = TIMER_EVENT_POS_EDGE;
+        }
+        else if (ch->polarity == PYBTIMER_POLARITY_NEG) {
+            polarity = TIMER_EVENT_NEG_EDGE;
+        }
+        MAP_TimerControlEvent(ch->timer->timer, ch->channel, polarity);
+    }
+
+#ifdef DEBUG
+    // stall the timer when the processor is halted while debugging
+    MAP_TimerControlStall(ch->timer->timer, ch->channel, true);
+#endif
+
+    // now enable the timer channel
+    MAP_TimerEnable(ch->timer->timer, ch->channel);
+}
+
+/******************************************************************************/
+/* Micro Python bindings                                                      */
+
+STATIC void pyb_timer_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    pyb_timer_obj_t *tim = self_in;
+    uint32_t mode = tim->config & 0xFF;
+
+    // timer mode
+    qstr mode_qst = MP_QSTR_PWM;
+    switch(mode) {
+    case TIMER_CFG_A_ONE_SHOT:
+        mode_qst = MP_QSTR_ONE_SHOT;
+        break;
+    case TIMER_CFG_A_PERIODIC:
+        mode_qst = MP_QSTR_PERIODIC;
+        break;
+    case TIMER_CFG_A_CAP_COUNT:
+        mode_qst = MP_QSTR_EDGE_COUNT;
+        break;
+    case TIMER_CFG_A_CAP_TIME:
+        mode_qst = MP_QSTR_EDGE_TIME;
+        break;
+    default:
+        break;
+    }
+    mp_printf(print, "<Timer%u, mode=Timer.%q>", tim->id, mode_qst);
+}
+
+/// \method init(mode, *, width)
+/// Initialise the timer.  Initialisation must give the desired mode
+/// and an optional timer width
+///
+///     tim.init(mode=Timer.PERIODIC)                  # configure in free running periodic mode
+///     tim.init(mode=Timer.ONE_SHOT, width=16)        # one shot mode splitted into two 16-bit independent timers
+///
+/// Keyword arguments:
+///
+///   - `width` - specifies the width of the timer. Default is 32 bit mode. When in 16 bit mode
+///               the timer is splitted into 2 independent channels.
+///
+STATIC mp_obj_t pyb_timer_init_helper(pyb_timer_obj_t *tim, 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_mode,         MP_ARG_REQUIRED | MP_ARG_INT, },
+        { MP_QSTR_width,        MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = 32} },
+    };
+
+    // parse args
+    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);
+
+    // check the mode
+    uint32_t _mode = args[0].u_int;
+    if (_mode != TIMER_CFG_A_ONE_SHOT && _mode != TIMER_CFG_A_PERIODIC && _mode != TIMER_CFG_A_CAP_COUNT &&
+        _mode != TIMER_CFG_A_CAP_TIME && _mode != TIMER_CFG_A_PWM) {
+        goto error;
+    }
+
+    // check the width
+    if (args[1].u_int != 16 && args[1].u_int != 32) {
+        goto error;
+    }
+    bool is16bit = (args[1].u_int == 16);
+
+    if (!is16bit && (_mode != TIMER_CFG_A_ONE_SHOT && _mode != TIMER_CFG_A_PERIODIC)) {
+        // 32-bit mode is only available when in free running modes
+        goto error;
+    }
+    tim->config = is16bit ? ((_mode | (_mode << 8)) | TIMER_CFG_SPLIT_PAIR) : _mode;
+
+    timer_init(tim);
+    // register it with the sleep module
+    pybsleep_add ((const mp_obj_t)tim, (WakeUpCB_t)timer_channel_init);
+
+    return mp_const_none;
+
+error:
+    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+}
+
+/// \classmethod \constructor(id, ...)
+/// Construct a new timer object of the given id.  If additional
+/// arguments are given, then the timer is initialised by `init(...)`.
+/// `id` can be 0 to 3
+STATIC mp_obj_t pyb_timer_make_new(mp_obj_t type_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
+    // check arguments
+    mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);
+
+    // create a new Timer object
+    uint32_t timer_idx = mp_obj_get_int(args[0]);
+    if (timer_idx < 0 || timer_idx > (PYBTIMER_NUM_TIMERS - 1)) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+    }
+
+    pyb_timer_obj_t *tim = &pyb_timer_obj[timer_idx];
+    tim->base.type = &pyb_timer_type;
+    tim->id = timer_idx;
+
+    if (n_args > 1 || n_kw > 0) {
+        // start the peripheral
+        mp_map_t kw_args;
+        mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
+        pyb_timer_init_helper(tim, n_args - 1, args + 1, &kw_args);
+    }
+    return (mp_obj_t)tim;
+}
+
+// \method init()
+/// initializes the timer
+STATIC mp_obj_t pyb_timer_init(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+    return pyb_timer_init_helper(args[0], n_args - 1, args + 1, kw_args);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_timer_init_obj, 1, pyb_timer_init);
+
+// \method deinit()
+/// disables the timer
+STATIC mp_obj_t pyb_timer_deinit(mp_obj_t self_in) {
+    pyb_timer_obj_t *self = self_in;
+    timer_disable(self);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_timer_deinit_obj, pyb_timer_deinit);
+
+/// \method channel(channel, *, freq, polarity, duty_cycle)
+/// Initialise the timer channel. Initialization requires at least a frequency param. With no
+/// extra params given besides the channel id, the channel is returned with the previous configuration
+/// os 'None', if it hasn't been initialized before.
+///
+///     tim1.channel(Timer.A, freq=1000)  # set channel A frequency to 1KHz
+///     tim2.channel(Timer.AB, freq=10)   # both channels (because it's a 32 bit timer) combined to create a 10Hz timer
+///
+///     when initialiazing the channel of a 32-bit timer, channel ID MUST be = Timer.AB
+///
+/// Keyword arguments:
+///
+///   - `freq` - specifies the frequency in Hz
+///
+///   - `polarity` - in PWM specifies the polarity of the pulse. In capture mode specifies the edge to capture.
+///                  in order to capture on both negative and positive edges, make it = Timer.POSITIVE | Timer.NEGATIVE.
+///
+STATIC mp_obj_t pyb_timer_channel(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_freq,                MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_polarity,            MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = PYBTIMER_POLARITY_POS} },
+        { MP_QSTR_duty_cycle,          MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = 0} },
+    };
+
+    pyb_timer_obj_t *tim = pos_args[0];
+    mp_int_t channel_n = mp_obj_get_int(pos_args[1]);
+
+    // verify that the timer has been already initialized
+    if (!tim->config) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+    }
+
+    if (channel_n != TIMER_A && channel_n != TIMER_B && channel_n != (TIMER_A | TIMER_B)) {
+        // invalid channel
+        goto error;
+    }
+    if (channel_n == (TIMER_A | TIMER_B) && (tim->config & TIMER_CFG_SPLIT_PAIR)) {
+        // 32-bit channel selected when the timer is in 16-bit mode
+        goto error;
+    }
+
+    // if only the channel number is given return the previously
+    // allocated channel (or None if no previous channel)
+    if (n_args == 2 && kw_args->used == 0) {
+        pyb_timer_channel_obj_t *ch;
+        if ((ch = pyb_timer_channel_find(tim->timer, channel_n))) {
+            return ch;
+        }
+        return mp_const_none;
+    }
+
+    // parse the arguments
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - 2, pos_args + 2, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // check the frequency
+    if (args[0].u_int <= 0) {
+        goto error;
+    }
+    // check that the polarity is not both in pwm mode
+    if ((tim->config & TIMER_A) == TIMER_CFG_A_PWM && args[1].u_int == (PYBTIMER_POLARITY_POS | PYBTIMER_POLARITY_NEG)) {
+        goto error;
+    }
+    // check the range of the duty cycle
+    if (args[2].u_int < 0 || args[2].u_int > 100) {
+        goto error;
+    }
+
+    // allocate a new timer channel
+    pyb_timer_channel_obj_t *ch = m_new_obj(pyb_timer_channel_obj_t);
+    ch->base.type = &pyb_timer_channel_type;
+    ch->timer = tim;
+    ch->channel = channel_n;
+
+    // get the frequency the polarity and the duty cycle
+    ch->frequency = args[0].u_int;
+    ch->polarity = args[1].u_int;
+    ch->duty_cycle = args[2].u_int;
+
+    timer_channel_init(ch);
+
+    // add the timer to the list
+    pyb_timer_channel_add(ch);
+
+    return ch;
+
+error:
+    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_timer_channel_obj, 2, pyb_timer_channel);
+
+STATIC const mp_map_elem_t pyb_timer_locals_dict_table[] = {
+    // instance methods
+    { MP_OBJ_NEW_QSTR(MP_QSTR_init),                    (mp_obj_t)&pyb_timer_init_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_deinit),                  (mp_obj_t)&pyb_timer_deinit_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_channel),                 (mp_obj_t)&pyb_timer_channel_obj },
+
+    // class constants
+    { MP_OBJ_NEW_QSTR(MP_QSTR_A),                       MP_OBJ_NEW_SMALL_INT(TIMER_A) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_B),                       MP_OBJ_NEW_SMALL_INT(TIMER_B) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_AB),                      MP_OBJ_NEW_SMALL_INT(TIMER_A | TIMER_B) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ONE_SHOT),                MP_OBJ_NEW_SMALL_INT(TIMER_CFG_A_ONE_SHOT) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_PERIODIC),                MP_OBJ_NEW_SMALL_INT(TIMER_CFG_A_PERIODIC) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_EDGE_COUNT),              MP_OBJ_NEW_SMALL_INT(TIMER_CFG_A_CAP_COUNT) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_EDGE_TIME),               MP_OBJ_NEW_SMALL_INT(TIMER_CFG_A_CAP_TIME) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_PWM),                     MP_OBJ_NEW_SMALL_INT(TIMER_CFG_A_PWM) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_POSITIVE),                MP_OBJ_NEW_SMALL_INT(PYBTIMER_POLARITY_POS) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_NEGATIVE),                MP_OBJ_NEW_SMALL_INT(PYBTIMER_POLARITY_NEG) },
+};
+STATIC MP_DEFINE_CONST_DICT(pyb_timer_locals_dict, pyb_timer_locals_dict_table);
+
+const mp_obj_type_t pyb_timer_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Timer,
+    .print = pyb_timer_print,
+    .make_new = pyb_timer_make_new,
+    .locals_dict = (mp_obj_t)&pyb_timer_locals_dict,
+};
+
+STATIC const mp_cb_methods_t pyb_timer_channel_cb_methods = {
+    .init = pyb_timer_channel_callback,
+    .enable = pyb_timer_channel_callback_enable,
+    .disable = pyb_timer_channel_callback_disable,
+};
+
+STATIC void TIMERGenericIntHandler(uint32_t timer, uint16_t channel) {
+    pyb_timer_channel_obj_t *self;
+    uint32_t status;
+
+    if ((self = pyb_timer_channel_find(timer, channel))) {
+        status = MAP_TimerIntStatus(self->timer->timer, true) & self->channel;
+        MAP_TimerIntClear(self->timer->timer, status);
+        mp_obj_t _callback = mpcallback_find(self);
+        mpcallback_handler(_callback);
+    }
+}
+
+STATIC void TIMER0AIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA0_BASE, TIMER_A);
+}
+
+STATIC void TIMER0BIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA0_BASE, TIMER_B);
+}
+
+STATIC void TIMER1AIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA1_BASE, TIMER_A);
+}
+
+STATIC void TIMER1BIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA1_BASE, TIMER_B);
+}
+
+STATIC void TIMER2AIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA2_BASE, TIMER_A);
+}
+
+STATIC void TIMER2BIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA2_BASE, TIMER_B);
+}
+
+STATIC void TIMER3AIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA3_BASE, TIMER_A);
+}
+
+STATIC void TIMER3BIntHandler(void) {
+    TIMERGenericIntHandler(TIMERA3_BASE, TIMER_B);
+}
+
+STATIC void pyb_timer_channel_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    pyb_timer_channel_obj_t *ch = self_in;
+    char *ch_id = "AB";
+    // timer channel
+    if (ch->channel == TIMER_A) {
+        ch_id = "A";
+    }
+    else if (ch->channel == TIMER_B) {
+        ch_id = "B";
+    }
+
+    mp_printf(print, "<%q %s, timer=%u, %q=%u", MP_QSTR_TimerChannel,
+              ch_id, ch->timer->id, MP_QSTR_freq, ch->frequency);
+
+    uint32_t mode = ch->timer->config & 0xFF;
+    if (mode == TIMER_CFG_A_CAP_COUNT || mode == TIMER_CFG_A_CAP_TIME || mode == TIMER_CFG_A_PWM) {
+        mp_printf(print, ", %q=Timer.", MP_QSTR_polarity);
+        switch (ch->polarity) {
+            case PYBTIMER_POLARITY_POS:
+                mp_printf(print, "POSITIVE");
+                break;
+            case PYBTIMER_POLARITY_NEG:
+                mp_printf(print, "NEGATIVE");
+                break;
+            default:
+                mp_printf(print, "BOTH");
+                break;
+        }
+        if (mode == TIMER_CFG_A_PWM) {
+            mp_printf(print, ", %q=%u", MP_QSTR_duty_cycle, ch->duty_cycle);
+        }
+    }
+    mp_printf(print, ">");
+}
+
+/// \method freq([value])
+/// get or set the frequency of the timer channel
+STATIC mp_obj_t pyb_timer_channel_freq(mp_uint_t n_args, const mp_obj_t *args) {
+    pyb_timer_channel_obj_t *ch = args[0];
+    if (n_args == 1) {
+        // get
+        return mp_obj_new_int(ch->frequency);
+    } else {
+        // set
+        ch->frequency = mp_obj_get_int(args[1]);
+        timer_channel_init(ch);
+        return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_timer_channel_freq_obj, 1, 2, pyb_timer_channel_freq);
+
+/// \method time([value])
+/// get or set the value of the timer channel in microseconds
+STATIC mp_obj_t pyb_timer_channel_time(mp_uint_t n_args, const mp_obj_t *args) {
+    pyb_timer_channel_obj_t *ch = args[0];
+    uint32_t value;
+    // calculate the period, the prescaler and the match value
+    uint32_t period;
+    uint32_t match;
+    (void)compute_prescaler_period_and_match_value(ch, &period, &match);
+    if (n_args == 1) {
+        // get
+        value = (ch->channel == TIMER_B) ? HWREG(ch->timer->timer + TIMER_O_TBV) : HWREG(ch->timer->timer + TIMER_O_TAV);
+        // return the current timer value in microseconds
+        // substract value to period since we are always operating in count-down mode
+        uint32_t time_t = (1000 * (period - value)) / period;
+        return mp_obj_new_int((time_t * 1000) / ch->frequency);
+    }
+    else {
+        // set
+        value = (mp_obj_get_int(args[1]) * ((ch->frequency * period) / 1000)) / 1000;
+        if ((value > 0xFFFF) && (ch->timer->config & TIMER_CFG_SPLIT_PAIR)) {
+            // this exceeds the maximum value of a 16-bit timer
+            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        }
+        // write period minus value since we are always operating in count-down mode
+        TimerValueSet (ch->timer->timer, ch->channel, (period - value));
+        return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_timer_channel_time_obj, 1, 2, pyb_timer_channel_time);
+
+/// \method event_count()
+/// get the number of events triggered by the configured edge
+STATIC mp_obj_t pyb_timer_channel_event_count(mp_obj_t self_in) {
+    pyb_timer_channel_obj_t *ch = self_in;
+    return mp_obj_new_int(MAP_TimerValueGet(ch->timer->timer, ch->channel == (TIMER_A | TIMER_B) ? TIMER_A : ch->channel));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_timer_channel_event_count_obj, pyb_timer_channel_event_count);
+
+/// \method event_time()
+/// get the time at which the last event was triggered
+STATIC mp_obj_t pyb_timer_channel_event_time(mp_obj_t self_in) {
+    pyb_timer_channel_obj_t *ch = self_in;
+    // calculate the period, the prescaler and the match value
+    uint32_t period;
+    uint32_t match;
+    (void)compute_prescaler_period_and_match_value(ch, &period, &match);
+    uint32_t value = MAP_TimerValueGet(ch->timer->timer, ch->channel == (TIMER_A | TIMER_B) ? TIMER_A : ch->channel);
+    // substract value to period since we are always operating in count-down mode
+    uint32_t time_t = (1000 * (period - value)) / period;
+    return mp_obj_new_int((time_t * 1000) / ch->frequency);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_timer_channel_event_time_obj, pyb_timer_channel_event_time);
+
+/// \method duty_cycle()
+/// get or set the duty cycle when in PWM mode
+STATIC mp_obj_t pyb_timer_channel_duty_cycle(mp_uint_t n_args, const mp_obj_t *args) {
+    pyb_timer_channel_obj_t *ch = args[0];
+    if (n_args == 1) {
+        // get
+        return mp_obj_new_int(ch->duty_cycle);
+    }
+    else {
+        // duty cycle must be converted from percentage to ticks
+        // calculate the period, the prescaler and the match value
+        uint32_t period;
+        uint32_t match;
+        ch->duty_cycle = mp_obj_get_int(args[1]);
+        compute_prescaler_period_and_match_value(ch, &period, &match);
+        if (n_args == 3) {
+            // set the new polarity if requested
+            ch->polarity = mp_obj_get_int(args[2]);
+            MAP_TimerControlLevel(ch->timer->timer, ch->channel, (ch->polarity == PYBTIMER_POLARITY_NEG) ? true : false);
+        }
+        MAP_TimerMatchSet(ch->timer->timer, ch->channel, match);
+        return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_timer_channel_duty_cycle_obj, 1, 3, pyb_timer_channel_duty_cycle);
+
+/// \method callback(handler, value, priority)
+/// create a callback object associated with the timer channel
+STATIC mp_obj_t pyb_timer_channel_callback (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    mp_arg_val_t args[mpcallback_INIT_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, mpcallback_INIT_NUM_ARGS, mpcallback_init_args, args);
+
+    pyb_timer_channel_obj_t *ch = pos_args[0];
+    mp_obj_t _callback = mpcallback_find(ch);
+    if (kw_args->used > 0 || !_callback) {
+        // convert the priority to the correct value
+        uint priority = mpcallback_translate_priority (args[2].u_int);
+
+        // validate the power mode
+        uint pwrmode = args[4].u_int;
+        if (pwrmode != PYB_PWR_MODE_ACTIVE) {
+            goto invalid_args;
+        }
+
+        // disable the callback first
+        pyb_timer_channel_callback_disable(ch);
+
+        uint32_t _config = (ch->channel == TIMER_B) ? ((ch->timer->config & TIMER_B) >> 8) : (ch->timer->config & TIMER_A);
+        uint8_t shift = (ch->channel == TIMER_B) ? 8 : 0;
+        switch (_config) {
+        case TIMER_CFG_A_ONE_SHOT:
+        case TIMER_CFG_A_PERIODIC:
+            ch->timer->intflags |= TIMER_TIMA_TIMEOUT << shift;
+            break;
+        case TIMER_CFG_A_CAP_COUNT:
+            ch->timer->intflags |= TIMER_CAPA_MATCH << shift;
+            break;
+        case TIMER_CFG_A_CAP_TIME:
+            ch->timer->intflags |= TIMER_CAPA_EVENT << shift;
+            break;
+        case TIMER_CFG_A_PWM:
+            // special case for the match interrupt
+            ch->timer->intflags |= ((ch->channel & TIMER_A) == TIMER_A) ? TIMER_TIMA_MATCH : TIMER_TIMB_MATCH;
+            break;
+        default:
+            break;
+        }
+        if (ch->channel == (TIMER_A | TIMER_B)) {
+            // again a special case for the match interrupt
+            if (_config == TIMER_CFG_A_PWM) {
+                ch->timer->intflags |= TIMER_TIMB_MATCH;
+            } else {
+                ch->timer->intflags |= (ch->timer->intflags << 8);
+            }
+        }
+
+        void (*pfnHandler)(void);
+        uint32_t intregister;
+        switch (ch->timer->timer) {
+        case TIMERA0_BASE:
+            if (ch->channel == TIMER_B) {
+                pfnHandler = &TIMER0BIntHandler;
+                intregister = INT_TIMERA0B;
+            } else {
+                pfnHandler = &TIMER0AIntHandler;
+                intregister = INT_TIMERA0A;
+            }
+            break;
+        case TIMERA1_BASE:
+            if (ch->channel == TIMER_B) {
+                pfnHandler = &TIMER1BIntHandler;
+                intregister = INT_TIMERA1B;
+            } else {
+                pfnHandler = &TIMER1AIntHandler;
+                intregister = INT_TIMERA1A;
+            }
+            break;
+        case TIMERA2_BASE:
+            if (ch->channel == TIMER_B) {
+                pfnHandler = &TIMER2BIntHandler;
+                intregister = INT_TIMERA2B;
+            } else {
+                pfnHandler = &TIMER2AIntHandler;
+                intregister = INT_TIMERA2A;
+            }
+            break;
+        default:
+            if (ch->channel == TIMER_B) {
+                pfnHandler = &TIMER3BIntHandler;
+                intregister = INT_TIMERA3B;
+            } else {
+                pfnHandler = &TIMER3AIntHandler;
+                intregister = INT_TIMERA3A;
+            }
+            break;
+        }
+
+        // register the interrupt and configure the priority
+        MAP_IntPrioritySet(intregister, priority);
+        MAP_TimerIntRegister(ch->timer->timer, ch->channel, pfnHandler);
+
+        // create the callback
+        _callback = mpcallback_new (ch, args[1].u_obj, &pyb_timer_channel_cb_methods);
+
+        // reload the timer
+        uint32_t period;
+        uint32_t match;
+        compute_prescaler_period_and_match_value(ch, &period, &match);
+        MAP_TimerLoadSet(ch->timer->timer, ch->channel, period);
+
+        // enable the callback before returning
+        pyb_timer_channel_callback_enable(ch);
+    }
+    return _callback;
+
+invalid_args:
+    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_timer_channel_callback_obj, 1, pyb_timer_channel_callback);
+
+STATIC const mp_map_elem_t pyb_timer_channel_locals_dict_table[] = {
+    // instance methods
+    { MP_OBJ_NEW_QSTR(MP_QSTR_freq),                 (mp_obj_t)&pyb_timer_channel_freq_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_time),                 (mp_obj_t)&pyb_timer_channel_time_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_event_count),          (mp_obj_t)&pyb_timer_channel_event_count_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_event_time),           (mp_obj_t)&pyb_timer_channel_event_time_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_duty_cycle),           (mp_obj_t)&pyb_timer_channel_duty_cycle_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_callback),             (mp_obj_t)&pyb_timer_channel_callback_obj },
+};
+STATIC MP_DEFINE_CONST_DICT(pyb_timer_channel_locals_dict, pyb_timer_channel_locals_dict_table);
+
+STATIC const mp_obj_type_t pyb_timer_channel_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_TimerChannel,
+    .print = pyb_timer_channel_print,
+    .locals_dict = (mp_obj_t)&pyb_timer_channel_locals_dict,
+};
+