esp8266/modonewire: Make timings static and remove onewire.timings func.

The 1-wire bus is defined with fixed timings so there should be no need to
change them dynamically at runtime.  Making the timings fixed saves about
270 bytes of code and 20 bytes of RAM.

Author: dpgeorge

esp8266/modonewire.c

@@ -33,69 +33,57 @@
 /******************************************************************************/
 // Low-level 1-Wire routines
 
-#define TIMING_RESET1 (0)
-#define TIMING_RESET2 (1)
-#define TIMING_RESET3 (2)
-#define TIMING_READ1 (3)
-#define TIMING_READ2 (4)
-#define TIMING_READ3 (5)
-#define TIMING_WRITE1 (6)
-#define TIMING_WRITE2 (7)
-#define TIMING_WRITE3 (8)
-
-STATIC uint16_t esp_onewire_timings[9] = {480, 40, 420, 5, 5, 40, 10, 50, 10};
+#define TIMING_RESET1 (480)
+#define TIMING_RESET2 (40)
+#define TIMING_RESET3 (420)
+#define TIMING_READ1 (5)
+#define TIMING_READ2 (5)
+#define TIMING_READ3 (40)
+#define TIMING_WRITE1 (10)
+#define TIMING_WRITE2 (50)
+#define TIMING_WRITE3 (10)
 
 STATIC int onewire_bus_reset(mp_hal_pin_obj_t pin) {
     mp_hal_pin_write(pin, 0);
-    mp_hal_delay_us(esp_onewire_timings[TIMING_RESET1]);
+    mp_hal_delay_us(TIMING_RESET1);
     uint32_t i = mp_hal_quiet_timing_enter();
     mp_hal_pin_write(pin, 1);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_RESET2]);
+    mp_hal_delay_us_fast(TIMING_RESET2);
     int status = !mp_hal_pin_read(pin);
     mp_hal_quiet_timing_exit(i);
-    mp_hal_delay_us(esp_onewire_timings[TIMING_RESET3]);
+    mp_hal_delay_us(TIMING_RESET3);
     return status;
 }
 
 STATIC int onewire_bus_readbit(mp_hal_pin_obj_t pin) {
     mp_hal_pin_write(pin, 1);
     uint32_t i = mp_hal_quiet_timing_enter();
     mp_hal_pin_write(pin, 0);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_READ1]);
+    mp_hal_delay_us_fast(TIMING_READ1);
     mp_hal_pin_write(pin, 1);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_READ2]);
+    mp_hal_delay_us_fast(TIMING_READ2);
     int value = mp_hal_pin_read(pin);
     mp_hal_quiet_timing_exit(i);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_READ3]);
+    mp_hal_delay_us_fast(TIMING_READ3);
     return value;
 }
 
 STATIC void onewire_bus_writebit(mp_hal_pin_obj_t pin, int value) {
     uint32_t i = mp_hal_quiet_timing_enter();
     mp_hal_pin_write(pin, 0);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_WRITE1]);
+    mp_hal_delay_us_fast(TIMING_WRITE1);
     if (value) {
         mp_hal_pin_write(pin, 1);
     }
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_WRITE2]);
+    mp_hal_delay_us_fast(TIMING_WRITE2);
     mp_hal_pin_write(pin, 1);
-    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_WRITE3]);
+    mp_hal_delay_us_fast(TIMING_WRITE3);
     mp_hal_quiet_timing_exit(i);
 }
 
 /******************************************************************************/
 // MicroPython bindings
 
-STATIC mp_obj_t onewire_timings(mp_obj_t timings_in) {
-    mp_obj_t *items;
-    mp_obj_get_array_fixed_n(timings_in, 9, &items);
-    for (int i = 0; i < 9; ++i) {
-        esp_onewire_timings[i] = mp_obj_get_int(items[i]);
-    }
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_timings_obj, onewire_timings);
-
 STATIC mp_obj_t onewire_reset(mp_obj_t pin_in) {
     return mp_obj_new_bool(onewire_bus_reset(mp_hal_get_pin_obj(pin_in)));
 }
@@ -158,7 +146,6 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_crc8_obj, onewire_crc8);
 STATIC const mp_map_elem_t onewire_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_onewire) },
 
-    { MP_ROM_QSTR(MP_QSTR_timings), MP_ROM_PTR((mp_obj_t)&onewire_timings_obj) },
     { MP_ROM_QSTR(MP_QSTR_reset), MP_ROM_PTR((mp_obj_t)&onewire_reset_obj) },
     { MP_ROM_QSTR(MP_QSTR_readbit), MP_ROM_PTR((mp_obj_t)&onewire_readbit_obj) },
     { MP_ROM_QSTR(MP_QSTR_readbyte), MP_ROM_PTR((mp_obj_t)&onewire_readbyte_obj) },