FourWire.c

// This file is part of the CircuitPython project: https://circuitpython.org
//
// SPDX-FileCopyrightText: Copyright (c) 2018-2019 Scott Shawcroft for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include "shared-bindings/fourwire/FourWire.h"

#include <stdint.h>

#include "shared/runtime/context_manager_helpers.h"
#include "py/binary.h"
#include "py/objproperty.h"
#include "py/runtime.h"
#include "shared-bindings/busio/SPI.h"
#include "shared-bindings/displayio/Group.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "shared-bindings/util.h"
#include "shared-module/displayio/__init__.h"

//| class FourWire:
//|     """Manage updating a display over SPI four wire protocol in the background while Python code runs.
//|     It doesn't handle display initialization.
//|
//|     .. seealso:: See `busdisplay.BusDisplay` and `epaperdisplay.EPaperDisplay`
//|         for how to initialize a display, given a `FourWire` bus.
//|     """
//|
//|     def __init__(
//|         self,
//|         spi_bus: busio.SPI,
//|         *,
//|         command: Optional[microcontroller.Pin],
//|         chip_select: Optional[microcontroller.Pin],
//|         reset: Optional[microcontroller.Pin] = None,
//|         baudrate: int = 24000000,
//|         polarity: int = 0,
//|         phase: int = 0,
//|     ) -> None:
//|         """Create a FourWire object associated with the given pins.
//|
//|         The SPI bus and pins are then in use by the display until `displayio.release_displays()` is
//|         called even after a reload. (It does this so CircuitPython can use the display after your code
//|         is done.) So, the first time you initialize a display bus in code.py you should call
//|         :py:func:`displayio.release_displays` first, otherwise it will error after the first code.py run.
//|
//|         If the ``command`` pin is not specified, a 9-bit SPI mode will be simulated by adding a
//|         data/command bit to every bit being transmitted, and splitting the resulting data back
//|         into 8-bit bytes for transmission. The extra bits that this creates at the end are ignored
//|         by the receiving device.
//|
//|         :param busio.SPI spi_bus: The SPI bus that make up the clock and data lines
//|         :param microcontroller.Pin command: Data or command pin. When None, 9-bit SPI is simulated.
//|         :param microcontroller.Pin chip_select: Chip select pin
//|         :param microcontroller.Pin reset: Reset pin. When None only software reset can be used
//|         :param int baudrate: Maximum baudrate in Hz for the display on the bus
//|         :param int polarity: the base state of the clock line (0 or 1)
//|         :param int phase: the edge of the clock that data is captured. First (0)
//|             or second (1). Rising or falling depends on clock polarity."""
//|         ...
//|
static mp_obj_t fourwire_fourwire_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
    enum { ARG_spi_bus, ARG_command, ARG_chip_select, ARG_reset, ARG_baudrate, ARG_polarity, ARG_phase };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_spi_bus, MP_ARG_REQUIRED | MP_ARG_OBJ },
        { MP_QSTR_command, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
        { MP_QSTR_chip_select, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
        { MP_QSTR_reset, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
        { MP_QSTR_baudrate, MP_ARG_INT | MP_ARG_KW_ONLY, {.u_int = 24000000} },
        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_phase, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
    };
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    const mcu_pin_obj_t *command = validate_obj_is_free_pin_or_none(args[ARG_command].u_obj, MP_QSTR_command);
    const mcu_pin_obj_t *chip_select = validate_obj_is_free_pin_or_none(args[ARG_chip_select].u_obj, MP_QSTR_chip_select);
    const mcu_pin_obj_t *reset = validate_obj_is_free_pin_or_none(args[ARG_reset].u_obj, MP_QSTR_reset);

    mp_obj_t spi = mp_arg_validate_type(args[ARG_spi_bus].u_obj, &busio_spi_type, MP_QSTR_spi_bus);

    fourwire_fourwire_obj_t *self = &allocate_display_bus_or_raise()->fourwire_bus;
    self->base.type = &fourwire_fourwire_type;

    uint8_t polarity = (uint8_t)mp_arg_validate_int_range(args[ARG_polarity].u_int, 0, 1, MP_QSTR_polarity);
    uint8_t phase = (uint8_t)mp_arg_validate_int_range(args[ARG_phase].u_int, 0, 1, MP_QSTR_phase);

    common_hal_fourwire_fourwire_construct(self,
        MP_OBJ_TO_PTR(spi), command, chip_select, reset, args[ARG_baudrate].u_int, polarity, phase);
    return self;
}

//|     def reset(self) -> None:
//|         """Performs a hardware reset via the reset pin. Raises an exception if called when no reset pin
//|         is available."""
//|         ...
//|
static mp_obj_t fourwire_fourwire_obj_reset(mp_obj_t self_in) {
    fourwire_fourwire_obj_t *self = self_in;

    if (!common_hal_fourwire_fourwire_reset(self)) {
        mp_raise_RuntimeError_varg(MP_ERROR_TEXT("No %q pin"), MP_QSTR_reset);
    }
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(fourwire_fourwire_reset_obj, fourwire_fourwire_obj_reset);

//|     def send(
//|         self, command: int, data: ReadableBuffer, *, toggle_every_byte: bool = False
//|     ) -> None:
//|         """Sends the given command value followed by the full set of data. Display state, such as
//|         vertical scroll, set via ``send`` may or may not be reset once the code is done."""
//|         ...
//|
//|
static mp_obj_t fourwire_fourwire_obj_send(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_command, ARG_data, ARG_toggle_every_byte };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_command, MP_ARG_INT | MP_ARG_REQUIRED },
        { MP_QSTR_data, MP_ARG_OBJ | MP_ARG_REQUIRED },
        { MP_QSTR_toggle_every_byte, MP_ARG_BOOL | MP_ARG_KW_ONLY, {.u_bool = false} },
    };
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    mp_int_t command_int = mp_arg_validate_int_range(args[ARG_command].u_int, 0, 255, MP_QSTR_command);

    fourwire_fourwire_obj_t *self = pos_args[0];
    uint8_t command = command_int;
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(args[ARG_data].u_obj, &bufinfo, MP_BUFFER_READ);

    // Wait for display bus to be available.
    while (!common_hal_fourwire_fourwire_begin_transaction(self)) {
        RUN_BACKGROUND_TASKS;
    }
    display_chip_select_behavior_t chip_select = CHIP_SELECT_UNTOUCHED;
    if (args[ARG_toggle_every_byte].u_bool) {
        chip_select = CHIP_SELECT_TOGGLE_EVERY_BYTE;
    }
    common_hal_fourwire_fourwire_send(self, DISPLAY_COMMAND, chip_select, &command, 1);
    common_hal_fourwire_fourwire_send(self, DISPLAY_DATA, chip_select, ((uint8_t *)bufinfo.buf), bufinfo.len);
    common_hal_fourwire_fourwire_end_transaction(self);

    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(fourwire_fourwire_send_obj, 1, fourwire_fourwire_obj_send);

static const mp_rom_map_elem_t fourwire_fourwire_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_reset), MP_ROM_PTR(&fourwire_fourwire_reset_obj) },
    { MP_ROM_QSTR(MP_QSTR_send), MP_ROM_PTR(&fourwire_fourwire_send_obj) },
};
static MP_DEFINE_CONST_DICT(fourwire_fourwire_locals_dict, fourwire_fourwire_locals_dict_table);

MP_DEFINE_CONST_OBJ_TYPE(
    fourwire_fourwire_type,
    MP_QSTR_FourWire,
    MP_TYPE_FLAG_NONE,
    make_new, fourwire_fourwire_make_new,
    locals_dict, &fourwire_fourwire_locals_dict
    );