1 files changed, 179 insertions, 0 deletions
diff --git a/circuitpython/shared-module/displayio/FourWire.c b/circuitpython/shared-module/displayio/FourWire.c
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+++ b/circuitpython/shared-module/displayio/FourWire.c
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+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 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 "shared-bindings/displayio/FourWire.h"
+
+#include <stdint.h>
+
+#include "py/gc.h"
+#include "shared-bindings/busio/SPI.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/microcontroller/__init__.h"
+#include "shared-bindings/time/__init__.h"
+#include "shared-module/displayio/display_core.h"
+
+void common_hal_displayio_fourwire_construct(displayio_fourwire_obj_t *self,
+    busio_spi_obj_t *spi, const mcu_pin_obj_t *command,
+    const mcu_pin_obj_t *chip_select, const mcu_pin_obj_t *reset, uint32_t baudrate,
+    uint8_t polarity, uint8_t phase) {
+
+    self->bus = spi;
+    common_hal_busio_spi_never_reset(self->bus);
+    // Our object is statically allocated off the heap so make sure the bus object lives to the end
+    // of the heap as well.
+    gc_never_free(self->bus);
+
+    self->frequency = baudrate;
+    self->polarity = polarity;
+    self->phase = phase;
+
+    common_hal_digitalio_digitalinout_construct(&self->chip_select, chip_select);
+    common_hal_digitalio_digitalinout_switch_to_output(&self->chip_select, true, DRIVE_MODE_PUSH_PULL);
+
+    self->command.base.type = &mp_type_NoneType;
+    if (command != NULL) {
+        self->command.base.type = &digitalio_digitalinout_type;
+        common_hal_digitalio_digitalinout_construct(&self->command, command);
+        common_hal_digitalio_digitalinout_switch_to_output(&self->command, true, DRIVE_MODE_PUSH_PULL);
+        common_hal_never_reset_pin(command);
+    }
+    self->reset.base.type = &mp_type_NoneType;
+    if (reset != NULL) {
+        self->reset.base.type = &digitalio_digitalinout_type;
+        common_hal_digitalio_digitalinout_construct(&self->reset, reset);
+        common_hal_digitalio_digitalinout_switch_to_output(&self->reset, true, DRIVE_MODE_PUSH_PULL);
+        common_hal_never_reset_pin(reset);
+        common_hal_displayio_fourwire_reset(self);
+    }
+
+    common_hal_never_reset_pin(chip_select);
+}
+
+void common_hal_displayio_fourwire_deinit(displayio_fourwire_obj_t *self) {
+    if (self->bus == &self->inline_bus) {
+        common_hal_busio_spi_deinit(self->bus);
+    }
+
+    common_hal_reset_pin(self->command.pin);
+    common_hal_reset_pin(self->chip_select.pin);
+    common_hal_reset_pin(self->reset.pin);
+}
+
+bool common_hal_displayio_fourwire_reset(mp_obj_t obj) {
+    displayio_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
+    if (self->reset.base.type == &mp_type_NoneType) {
+        return false;
+    }
+    common_hal_digitalio_digitalinout_set_value(&self->reset, false);
+    common_hal_mcu_delay_us(1000);
+    common_hal_digitalio_digitalinout_set_value(&self->reset, true);
+    common_hal_mcu_delay_us(1000);
+    return true;
+}
+
+bool common_hal_displayio_fourwire_bus_free(mp_obj_t obj) {
+    displayio_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
+    if (!common_hal_busio_spi_try_lock(self->bus)) {
+        return false;
+    }
+    common_hal_busio_spi_unlock(self->bus);
+    return true;
+}
+
+bool common_hal_displayio_fourwire_begin_transaction(mp_obj_t obj) {
+    displayio_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
+    if (!common_hal_busio_spi_try_lock(self->bus)) {
+        return false;
+    }
+    common_hal_busio_spi_configure(self->bus, self->frequency, self->polarity,
+        self->phase, 8);
+    common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+    return true;
+}
+
+void common_hal_displayio_fourwire_send(mp_obj_t obj, display_byte_type_t data_type,
+    display_chip_select_behavior_t chip_select, const uint8_t *data, uint32_t data_length) {
+    displayio_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
+    if (self->command.base.type == &mp_type_NoneType) {
+        // When the data/command pin is not specified, we simulate a 9-bit SPI mode, by
+        // adding a data/command bit to every byte, and then splitting the resulting data back
+        // into 8-bit chunks for transmission. If the length of the data being transmitted
+        // is not a multiple of 8, there will be additional bits at the end of the
+        // transmission. We toggle the CS pin to make the receiver discard them.
+        uint8_t buffer = 0;
+        uint8_t bits = 0;
+        uint8_t dc = (data_type == DISPLAY_DATA);
+
+        for (size_t i = 0; i < data_length; i++) {
+            bits = (bits + 1) % 8;
+
+            if (bits == 0) {
+                // send the previous byte and the dc bit
+                // we will send the current byte later
+                buffer = (buffer << 1) | dc;
+                common_hal_busio_spi_write(self->bus, &buffer, 1);
+                // send the current byte, because previous byte already filled all bits
+                common_hal_busio_spi_write(self->bus, &data[i], 1);
+            } else {
+                // send remaining bits from previous byte, dc and beginning of current byte
+                buffer = (buffer << (9 - bits)) | (dc << (8 - bits)) | (data[i] >> bits);
+                common_hal_busio_spi_write(self->bus, &buffer, 1);
+            }
+            // save the current byte
+            buffer = data[i];
+        }
+        // send any remaining bits
+        if (bits > 0) {
+            buffer = buffer << (8 - bits);
+            common_hal_busio_spi_write(self->bus, &buffer, 1);
+            // toggle CS to discard superfluous bits
+            common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+            common_hal_mcu_delay_us(1);
+            common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+        }
+    } else {
+        common_hal_digitalio_digitalinout_set_value(&self->command, data_type == DISPLAY_DATA);
+        if (chip_select == CHIP_SELECT_TOGGLE_EVERY_BYTE) {
+            // Toggle chip select after each command byte in case the display driver
+            // IC latches commands based on it.
+            for (size_t i = 0; i < data_length; i++) {
+                common_hal_busio_spi_write(self->bus, &data[i], 1);
+                common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+                common_hal_mcu_delay_us(1);
+                common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+            }
+        } else {
+            common_hal_busio_spi_write(self->bus, data, data_length);
+        }
+    }
+}
+
+void common_hal_displayio_fourwire_end_transaction(mp_obj_t obj) {
+    displayio_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
+    common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+    common_hal_busio_spi_unlock(self->bus);
+}