esp8266/modonewire: Move low-level 1-wire bus code to modonewire.c.

The reason it was separated is so that the low-level code could be put in
iRAM, for timing reasons.  But:

1. Tests show that it's not necessary to have this code in iRAM for it to
function correctly, and taking it out of iRAM reclaims some of that precious
resource.  Furthermore, even though these functions were in iRAM there were
some functions that it called (eg pin get/set functions) which were not in
iRAM, so partially defeated the purpose of putting the 1-wire code in iRAM.

2. It's easier to reuse this 1-wire code in other ports if it's in a single
file.

3. If it turns out that certain code does need to be in iRAM then one can
use the MP_FASTCODE macro to do that.

1 files changed, 62 insertions, 8 deletions

diff --git a/esp8266/modonewire.c b/esp8266/modonewire.c
index a8b40baaa5..9831ae552a 100644
--- a/esp8266/modonewire.c
+++ b/esp8266/modonewire.c
@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2015 Damien P. George
+ * Copyright (c) 2015-2017 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
@@ -29,8 +29,62 @@
 
 #include "py/obj.h"
 #include "py/mphal.h"
-#include "modmachine.h"
-#include "esponewire.h"
+
+/******************************************************************************/
+// 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};
+
+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]);
+    uint32_t i = mp_hal_quiet_timing_enter();
+    mp_hal_pin_write(pin, 1);
+    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_RESET2]);
+    int status = !mp_hal_pin_read(pin);
+    mp_hal_quiet_timing_exit(i);
+    mp_hal_delay_us(esp_onewire_timings[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_pin_write(pin, 1);
+    mp_hal_delay_us_fast(esp_onewire_timings[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]);
+    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]);
+    if (value) {
+        mp_hal_pin_write(pin, 1);
+    }
+    mp_hal_delay_us_fast(esp_onewire_timings[TIMING_WRITE2]);
+    mp_hal_pin_write(pin, 1);
+    mp_hal_delay_us_fast(esp_onewire_timings[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;
@@ -43,12 +97,12 @@ STATIC mp_obj_t onewire_timings(mp_obj_t timings_in) {
 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(esp_onewire_reset(mp_hal_get_pin_obj(pin_in)));
+    return mp_obj_new_bool(onewire_bus_reset(mp_hal_get_pin_obj(pin_in)));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_reset_obj, onewire_reset);
 
 STATIC mp_obj_t onewire_readbit(mp_obj_t pin_in) {
-    return MP_OBJ_NEW_SMALL_INT(esp_onewire_readbit(mp_hal_get_pin_obj(pin_in)));
+    return MP_OBJ_NEW_SMALL_INT(onewire_bus_readbit(mp_hal_get_pin_obj(pin_in)));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbit_obj, onewire_readbit);
 
@@ -56,14 +110,14 @@ STATIC mp_obj_t onewire_readbyte(mp_obj_t pin_in) {
     mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
     uint8_t value = 0;
     for (int i = 0; i < 8; ++i) {
-        value |= esp_onewire_readbit(pin) << i;
+        value |= onewire_bus_readbit(pin) << i;
     }
     return MP_OBJ_NEW_SMALL_INT(value);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbyte_obj, onewire_readbyte);
 
 STATIC mp_obj_t onewire_writebit(mp_obj_t pin_in, mp_obj_t value_in) {
-    esp_onewire_writebit(mp_hal_get_pin_obj(pin_in), mp_obj_get_int(value_in));
+    onewire_bus_writebit(mp_hal_get_pin_obj(pin_in), mp_obj_get_int(value_in));
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(onewire_writebit_obj, onewire_writebit);
@@ -72,7 +126,7 @@ STATIC mp_obj_t onewire_writebyte(mp_obj_t pin_in, mp_obj_t value_in) {
     mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
     int value = mp_obj_get_int(value_in);
     for (int i = 0; i < 8; ++i) {
-        esp_onewire_writebit(pin, value & 1);
+        onewire_bus_writebit(pin, value & 1);
         value >>= 1;
     }
     return mp_const_none;