add circuitpython code

1 files changed, 89 insertions, 0 deletions

diff --git a/circuitpython/shared-module/onewireio/OneWire.c b/circuitpython/shared-module/onewireio/OneWire.c
new file mode 100644
index 0000000..aeb4dcb
--- /dev/null
+++ b/circuitpython/shared-module/onewireio/OneWire.c
@@ -0,0 +1,89 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * 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 "common-hal/microcontroller/Pin.h"
+#include "shared-bindings/onewireio/OneWire.h"
+#include "shared-bindings/microcontroller/__init__.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+
+// Durations are taken from here: https://www.maximintegrated.com/en/app-notes/index.mvp/id/126
+
+void common_hal_onewireio_onewire_construct(onewireio_onewire_obj_t *self,
+    const mcu_pin_obj_t *pin) {
+    self->pin.base.type = &digitalio_digitalinout_type;
+    common_hal_digitalio_digitalinout_construct(&self->pin, pin);
+}
+
+bool common_hal_onewireio_onewire_deinited(onewireio_onewire_obj_t *self) {
+    return common_hal_digitalio_digitalinout_deinited(&self->pin);
+}
+
+void common_hal_onewireio_onewire_deinit(onewireio_onewire_obj_t *self) {
+    if (common_hal_onewireio_onewire_deinited(self)) {
+        return;
+    }
+    common_hal_digitalio_digitalinout_deinit(&self->pin);
+}
+
+// We use common_hal_mcu_delay_us(). It should not be dependent on interrupts
+// to do accurate timekeeping, since we disable interrupts during the delays below.
+
+bool common_hal_onewireio_onewire_reset(onewireio_onewire_obj_t *self) {
+    common_hal_mcu_disable_interrupts();
+    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
+    common_hal_mcu_delay_us(480);
+    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
+    common_hal_mcu_delay_us(70);
+    bool value = common_hal_digitalio_digitalinout_get_value(&self->pin);
+    common_hal_mcu_delay_us(410);
+    common_hal_mcu_enable_interrupts();
+    return value;
+}
+
+bool common_hal_onewireio_onewire_read_bit(onewireio_onewire_obj_t *self) {
+    common_hal_mcu_disable_interrupts();
+    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
+    common_hal_mcu_delay_us(6);
+    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
+    // TODO(tannewt): Test with more devices and maybe make the delays
+    // configurable. This should be 9 by the datasheet but all bits read as 1
+    // then.
+    common_hal_mcu_delay_us(6);
+    bool value = common_hal_digitalio_digitalinout_get_value(&self->pin);
+    common_hal_mcu_delay_us(55);
+    common_hal_mcu_enable_interrupts();
+    return value;
+}
+
+void common_hal_onewireio_onewire_write_bit(onewireio_onewire_obj_t *self,
+    bool bit) {
+    common_hal_mcu_disable_interrupts();
+    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
+    common_hal_mcu_delay_us(bit? 6 : 60);
+    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
+    common_hal_mcu_delay_us(bit? 64 : 10);
+    common_hal_mcu_enable_interrupts();
+}