stmhal: Add machine.WDT class.

Usage:

    import machine
    wdt = machine.WDT(0, 5000) # 5 second timeout
    wdt.feed()

Thanks to Moritz for the initial implementation.

stmhal/Makefile

@@ -138,6 +138,7 @@ SRC_C = \
 	uart.c \
 	can.c \
 	usb.c \
+	wdt.c \
 	gccollect.c \
 	pybstdio.c \
 	help.c \

stmhal/modmachine.c

@@ -44,6 +44,7 @@
 #include "rtc.h"
 #include "i2c.h"
 #include "spi.h"
+#include "wdt.h"
 
 // machine.info([dump_alloc_table])
 // Print out lots of information about the board.
@@ -490,10 +491,10 @@ STATIC const mp_map_elem_t machine_module_globals_table[] = {
     // initialize master mode on the peripheral.
     { MP_OBJ_NEW_QSTR(MP_QSTR_I2C),                 (mp_obj_t)&machine_i2c_type },
     { MP_OBJ_NEW_QSTR(MP_QSTR_SPI),                 (mp_obj_t)&pyb_spi_type },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_WDT),                 (mp_obj_t)&pyb_wdt_type },
 #if 0
     { MP_OBJ_NEW_QSTR(MP_QSTR_UART),                (mp_obj_t)&pyb_uart_type },
     { MP_OBJ_NEW_QSTR(MP_QSTR_Timer),               (mp_obj_t)&pyb_timer_type },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_WDT),                 (mp_obj_t)&pyb_wdt_type },
     { MP_OBJ_NEW_QSTR(MP_QSTR_HeartBeat),           (mp_obj_t)&pyb_heartbeat_type },
     { MP_OBJ_NEW_QSTR(MP_QSTR_SD),                  (mp_obj_t)&pyb_sd_type },
 

stmhal/wdt.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * 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 <stdio.h>
+
+#include STM32_HAL_H
+
+#include "py/runtime.h"
+#include "wdt.h"
+
+typedef struct _pyb_wdt_obj_t {
+    mp_obj_base_t base;
+} pyb_wdt_obj_t;
+
+STATIC pyb_wdt_obj_t pyb_wdt = {{&pyb_wdt_type}};
+
+STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    // check arguments
+    mp_arg_check_num(n_args, n_kw, 2, 2, false);
+
+    mp_int_t id = mp_obj_get_int(args[0]);
+    if (id != 0) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "WDT(%d) does not exist", id));
+    }
+
+    // timeout is in milliseconds
+    mp_int_t timeout = mp_obj_get_int(args[1]);
+
+    // compute prescaler
+    uint32_t prescaler;
+    for (prescaler = 0; prescaler < 6 && timeout >= 512; ++prescaler, timeout /= 2) {
+    }
+
+    // convert milliseconds to ticks
+    timeout *= 8; // 32kHz / 4 = 8 ticks per millisecond (approx)
+    if (timeout <= 0) {
+        mp_raise_ValueError("WDT timeout too short");
+    } else if (timeout > 0xfff) {
+        mp_raise_ValueError("WDT timeout too long");
+    }
+    timeout -= 1;
+
+    // set the reload register
+    while (IWDG->SR & 2) {
+    }
+    IWDG->KR = 0x5555;
+    IWDG->RLR = timeout;
+
+    // set the prescaler
+    while (IWDG->SR & 1) {
+    }
+    IWDG->KR = 0x5555;
+    IWDG->PR = prescaler;
+
+    // start the watch dog
+    IWDG->KR = 0xcccc;
+
+    return (mp_obj_t)&pyb_wdt;
+}
+
+STATIC mp_obj_t pyb_wdt_feed(mp_obj_t self_in) {
+    (void)self_in;
+    IWDG->KR = 0xaaaa;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_wdt_feed_obj, pyb_wdt_feed);
+
+STATIC const mp_map_elem_t pyb_wdt_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_feed), (mp_obj_t)&pyb_wdt_feed_obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(pyb_wdt_locals_dict, pyb_wdt_locals_dict_table);
+
+const mp_obj_type_t pyb_wdt_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_WDT,
+    .make_new = pyb_wdt_make_new,
+    .locals_dict = (mp_obj_t)&pyb_wdt_locals_dict,
+};

stmhal/wdt.h

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * 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.
+ */
+
+extern const mp_obj_type_t pyb_wdt_type;