esp8266,esp32: Implement high-res timers using new tick_hz argument.

machine.Timer now takes a new argument in its constructor (or init method):
tick_hz which specified the units for the period argument.  The period of
the timer in seconds is: period/tick_hz.

For backwards compatibility tick_hz defaults to 1000.  If the user wants to
specify the period (numerator) in microseconds then tick_hz can be set to
1000000.  The user can also specify a period of an arbitrary number of
cycles of an arbitrary frequency using these two arguments.

An additional freq argument has been added to allow frequencies to be
specified directly in Hertz.  This supports floating point values when
available.

1 files changed, 51 insertions, 4 deletions

diff --git a/ports/esp8266/modmachine.c b/ports/esp8266/modmachine.c
index 7e5f6714b..1c1d902e5 100644
--- a/ports/esp8266/modmachine.c
+++ b/ports/esp8266/modmachine.c
@@ -30,6 +30,10 @@
 
 #include "py/obj.h"
 #include "py/runtime.h"
+
+// This needs to be set before we include the RTOS headers
+#define USE_US_TIMER 1
+
 #include "extmod/machine_mem.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
@@ -160,22 +164,65 @@ STATIC void esp_timer_cb(void *arg) {
 }
 
 STATIC mp_obj_t esp_timer_init_helper(esp_timer_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum {
+        ARG_mode,
+        ARG_callback,
+        ARG_period,
+        ARG_tick_hz,
+        ARG_freq,
+    };
     static const mp_arg_t allowed_args[] = {
-//        { MP_QSTR_freq,         MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
-        { 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} },
+        { MP_QSTR_period,       MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+        { MP_QSTR_tick_hz,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1000} },
+#if MICROPY_PY_BUILTINS_FLOAT
+        { MP_QSTR_freq,         MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+#else
+        { MP_QSTR_freq,         MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+#endif
     };
 
     // 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);
 
-    self->callback = args[2].u_obj;
+    self->callback = args[ARG_callback].u_obj;
     // Be sure to disarm timer before making any changes
     os_timer_disarm(&self->timer);
     os_timer_setfn(&self->timer, esp_timer_cb, self);
-    os_timer_arm(&self->timer, args[0].u_int, args[1].u_int);
+
+#if MICROPY_PY_BUILTINS_FLOAT
+    if (args[ARG_freq].u_obj != mp_const_none) {
+        mp_float_t freq = mp_obj_get_float(args[ARG_freq].u_obj);
+        if (freq < 0.001) {
+            os_timer_arm(&self->timer, (mp_int_t)(1000 / freq), args[ARG_mode].u_int);
+        } else {
+            os_timer_arm_us(&self->timer, (mp_int_t)(1000000 / freq), args[ARG_mode].u_int);
+        }
+    }
+#else
+    if (args[ARG_freq].u_int != 0xffffffff) {
+        os_timer_arm_us(&self->timer, 1000000 / args[ARG_freq].u_int, args[ARG_mode].u_int);
+    }
+#endif
+    else {
+        mp_int_t period = args[ARG_period].u_int;
+        mp_int_t hz = args[ARG_tick_hz].u_int;
+        if (hz == 1000) {
+            os_timer_arm(&self->timer, period, args[ARG_mode].u_int);
+        } else if (hz == 1000000) {
+            os_timer_arm_us(&self->timer, period, args[ARG_mode].u_int);
+        } else {
+            // Use a long long to ensure that we don't either overflow or loose accuracy
+            uint64_t period_us = (((uint64_t)period) * 1000000) / hz;
+            if (period_us < 0x80000000ull) {
+                os_timer_arm_us(&self->timer, (mp_int_t)period_us, args[ARG_mode].u_int);
+            } else {
+                os_timer_arm(&self->timer, (mp_int_t)(period_us / 1000), args[ARG_mode].u_int);
+            }
+        }
+    }
 
     return mp_const_none;
 }