circuitpython/ports/stm32/lcd.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 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
 * 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 <stdio.h>
#include <string.h>

#include "py/mphal.h"
#include "py/runtime.h"

#if MICROPY_HW_HAS_LCD

#include "pin.h"
#include "genhdr/pins.h"
#include "bufhelper.h"
#include "spi.h"
#include "font_petme128_8x8.h"
#include "lcd.h"

/// \moduleref pyb
/// \class LCD - LCD control for the LCD touch-sensor pyskin
///
/// The LCD class is used to control the LCD on the LCD touch-sensor pyskin,
/// LCD32MKv1.0.  The LCD is a 128x32 pixel monochrome screen, part NHD-C12832A1Z.
///
/// The pyskin must be connected in either the X or Y positions, and then
/// an LCD object is made using:
///
///     lcd = pyb.LCD('X')      # if pyskin is in the X position
///     lcd = pyb.LCD('Y')      # if pyskin is in the Y position
///
/// Then you can use:
///
///     lcd.light(True)                 # turn the backlight on
///     lcd.write('Hello world!\n')     # print text to the screen
///
/// This driver implements a double buffer for setting/getting pixels.
/// For example, to make a bouncing dot, try:
///
///     x = y = 0
///     dx = dy = 1
///     while True:
///         # update the dot's position
///         x += dx
///         y += dy
///
///         # make the dot bounce of the edges of the screen
///         if x <= 0 or x >= 127: dx = -dx
///         if y <= 0 or y >= 31: dy = -dy
///
///         lcd.fill(0)                 # clear the buffer
///         lcd.pixel(x, y, 1)          # draw the dot
///         lcd.show()                  # show the buffer
///         pyb.delay(50)               # pause for 50ms

#define LCD_INSTR (0)
#define LCD_DATA (1)

#define LCD_CHAR_BUF_W (16)
#define LCD_CHAR_BUF_H (4)

#define LCD_PIX_BUF_W (128)
#define LCD_PIX_BUF_H (32)
#define LCD_PIX_BUF_BYTE_SIZE (LCD_PIX_BUF_W * LCD_PIX_BUF_H / 8)

typedef struct _pyb_lcd_obj_t {
    mp_obj_base_t base;

    // hardware control for the LCD
    const spi_t *spi;
    const pin_obj_t *pin_cs1;
    const pin_obj_t *pin_rst;
    const pin_obj_t *pin_a0;
    const pin_obj_t *pin_bl;

    // character buffer for stdout-like output
    char char_buffer[LCD_CHAR_BUF_W * LCD_CHAR_BUF_H];
    int line;
    int column;
    int next_line;

    // double buffering for pixel buffer
    byte pix_buf[LCD_PIX_BUF_BYTE_SIZE];
    byte pix_buf2[LCD_PIX_BUF_BYTE_SIZE];
} pyb_lcd_obj_t;

STATIC void lcd_delay(void) {
    __asm volatile ("nop\nnop");
}

STATIC void lcd_out(pyb_lcd_obj_t *lcd, int instr_data, uint8_t i) {
    lcd_delay();
    mp_hal_pin_low(lcd->pin_cs1); // CS=0; enable
    if (instr_data == LCD_INSTR) {
        mp_hal_pin_low(lcd->pin_a0); // A0=0; select instr reg
    } else {
        mp_hal_pin_high(lcd->pin_a0); // A0=1; select data reg
    }
    lcd_delay();
    HAL_SPI_Transmit(lcd->spi->spi, &i, 1, 1000);
    lcd_delay();
    mp_hal_pin_high(lcd->pin_cs1); // CS=1; disable
}

// write a string to the LCD at the current cursor location
// output it straight away (doesn't use the pixel buffer)
STATIC void lcd_write_strn(pyb_lcd_obj_t *lcd, const char *str, unsigned int len) {
    int redraw_min = lcd->line * LCD_CHAR_BUF_W + lcd->column;
    int redraw_max = redraw_min;
    for (; len > 0; len--, str++) {
        // move to next line if needed
        if (lcd->next_line) {
            if (lcd->line + 1 < LCD_CHAR_BUF_H) {
                lcd->line += 1;
            } else {
                lcd->line = LCD_CHAR_BUF_H - 1;
                for (int i = 0; i < LCD_CHAR_BUF_W * (LCD_CHAR_BUF_H - 1); i++) {
                    lcd->char_buffer[i] = lcd->char_buffer[i + LCD_CHAR_BUF_W];
                }
                for (int i = 0; i < LCD_CHAR_BUF_W; i++) {
                    lcd->char_buffer[LCD_CHAR_BUF_W * (LCD_CHAR_BUF_H - 1) + i] = ' ';
                }
                redraw_min = 0;
                redraw_max = LCD_CHAR_BUF_W * LCD_CHAR_BUF_H;
            }
            lcd->next_line = 0;
            lcd->column = 0;
        }
        if (*str == '\n') {
            lcd->next_line = 1;
        } else if (*str == '\r') {
            lcd->column = 0;
        } else if (*str == '\b') {
            if (lcd->column > 0) {
                lcd->column--;
                redraw_min = 0; // could optimise this to not redraw everything
            }
        } else if (lcd->column >= LCD_CHAR_BUF_W) {
            lcd->next_line = 1;
            str -= 1;
            len += 1;
        } else {
            lcd->char_buffer[lcd->line * LCD_CHAR_BUF_W + lcd->column] = *str;
            lcd->column += 1;
            int max = lcd->line * LCD_CHAR_BUF_W + lcd->column;
            if (max > redraw_max) {
                redraw_max = max;
            }
        }
    }

    // we must draw upside down, because the LCD is upside down
    for (int i = redraw_min; i < redraw_max; i++) {
        uint page = i / LCD_CHAR_BUF_W;
        uint offset = 8 * (LCD_CHAR_BUF_W - 1 - (i - (page * LCD_CHAR_BUF_W)));
        lcd_out(lcd, LCD_INSTR, 0xb0 | page); // page address set
        lcd_out(lcd, LCD_INSTR, 0x10 | ((offset >> 4) & 0x0f)); // column address set upper
        lcd_out(lcd, LCD_INSTR, 0x00 | (offset & 0x0f)); // column address set lower
        int chr = lcd->char_buffer[i];
        if (chr < 32 || chr > 126) {
            chr = 127;
        }
        const uint8_t *chr_data = &font_petme128_8x8[(chr - 32) * 8];
        for (int j = 7; j >= 0; j--) {
            lcd_out(lcd, LCD_DATA, chr_data[j]);
        }
    }
}

/// \classmethod \constructor(skin_position)
///
/// Construct an LCD object in the given skin position.  `skin_position` can be 'X' or 'Y', and
/// should match the position where the LCD pyskin is plugged in.
STATIC mp_obj_t pyb_lcd_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
    // check arguments
    mp_arg_check_num(n_args, n_kw, 1, 1, false);

    // get LCD position
    const char *lcd_id = mp_obj_str_get_str(args[0]);

    // create lcd object
    pyb_lcd_obj_t *lcd = m_new_obj(pyb_lcd_obj_t);
    lcd->base.type = &pyb_lcd_type;

    // configure pins
    // TODO accept an SPI object and pin objects for full customisation
    if ((lcd_id[0] | 0x20) == 'x' && lcd_id[1] == '\0') {
        lcd->spi = &spi_obj[0];
        lcd->pin_cs1 = &pyb_pin_X3;
        lcd->pin_rst = &pyb_pin_X4;
        lcd->pin_a0 = &pyb_pin_X5;
        lcd->pin_bl = &pyb_pin_X12;
    } else if ((lcd_id[0] | 0x20) == 'y' && lcd_id[1] == '\0') {
        lcd->spi = &spi_obj[1];
        lcd->pin_cs1 = &pyb_pin_Y3;
        lcd->pin_rst = &pyb_pin_Y4;
        lcd->pin_a0 = &pyb_pin_Y5;
        lcd->pin_bl = &pyb_pin_Y12;
    } else {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "LCD(%s) doesn't exist", lcd_id));
    }

    // init the SPI bus
    SPI_InitTypeDef *init = &lcd->spi->spi->Init;
    init->Mode = SPI_MODE_MASTER;

    // compute the baudrate prescaler from the desired baudrate
    // select a prescaler that yields at most the desired baudrate
    uint spi_clock;
    if (lcd->spi->spi->Instance == SPI1) {
        // SPI1 is on APB2
        spi_clock = HAL_RCC_GetPCLK2Freq();
    } else {
        // SPI2 and SPI3 are on APB1
        spi_clock = HAL_RCC_GetPCLK1Freq();
    }
    uint br_prescale = spi_clock / 16000000; // datasheet says LCD can run at 20MHz, but we go for 16MHz
    if (br_prescale <= 2) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_2; }
    else if (br_prescale <= 4) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_4; }
    else if (br_prescale <= 8) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_8; }
    else if (br_prescale <= 16) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16; }
    else if (br_prescale <= 32) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32; }
    else if (br_prescale <= 64) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_64; }
    else if (br_prescale <= 128) { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_128; }
    else { init->BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256; }

    // data is sent bigendian, latches on rising clock
    init->CLKPolarity = SPI_POLARITY_HIGH;
    init->CLKPhase = SPI_PHASE_2EDGE;
    init->Direction = SPI_DIRECTION_2LINES;
    init->DataSize = SPI_DATASIZE_8BIT;
    init->NSS = SPI_NSS_SOFT;
    init->FirstBit = SPI_FIRSTBIT_MSB;
    init->TIMode = SPI_TIMODE_DISABLED;
    init->CRCCalculation = SPI_CRCCALCULATION_DISABLED;
    init->CRCPolynomial = 0;

    // init the SPI bus
    spi_init(lcd->spi, false);

    // set the pins to default values
    mp_hal_pin_high(lcd->pin_cs1);
    mp_hal_pin_high(lcd->pin_rst);
    mp_hal_pin_high(lcd->pin_a0);
    mp_hal_pin_low(lcd->pin_bl);

    // init the pins to be push/pull outputs
    mp_hal_pin_output(lcd->pin_cs1);
    mp_hal_pin_output(lcd->pin_rst);
    mp_hal_pin_output(lcd->pin_a0);
    mp_hal_pin_output(lcd->pin_bl);

    // init the LCD
    mp_hal_delay_ms(1); // wait a bit
    mp_hal_pin_low(lcd->pin_rst); // RST=0; reset
    mp_hal_delay_ms(1); // wait for reset; 2us min
    mp_hal_pin_high(lcd->pin_rst); // RST=1; enable
    mp_hal_delay_ms(1); // wait for reset; 2us min
    lcd_out(lcd, LCD_INSTR, 0xa0); // ADC select, normal
    lcd_out(lcd, LCD_INSTR, 0xc0); // common output mode select, normal (this flips the display)
    lcd_out(lcd, LCD_INSTR, 0xa2); // LCD bias set, 1/9 bias
    lcd_out(lcd, LCD_INSTR, 0x2f); // power control set, 0b111=(booster on, vreg on, vfollow on)
    lcd_out(lcd, LCD_INSTR, 0x21); // v0 voltage regulator internal resistor ratio set, 0b001=small
    lcd_out(lcd, LCD_INSTR, 0x81); // electronic volume mode set
    lcd_out(lcd, LCD_INSTR, 0x28); // electronic volume register set
    lcd_out(lcd, LCD_INSTR, 0x40); // display start line set, 0
    lcd_out(lcd, LCD_INSTR, 0xaf); // LCD display, on

    // clear LCD RAM
    for (int page = 0; page < 4; page++) {
        lcd_out(lcd, LCD_INSTR, 0xb0 | page); // page address set
        lcd_out(lcd, LCD_INSTR, 0x10); // column address set upper
        lcd_out(lcd, LCD_INSTR, 0x00); // column address set lower
        for (int i = 0; i < 128; i++) {
            lcd_out(lcd, LCD_DATA, 0x00);
        }
    }

    // clear local char buffer
    memset(lcd->char_buffer, ' ', LCD_CHAR_BUF_H * LCD_CHAR_BUF_W);
    lcd->line = 0;
    lcd->column = 0;
    lcd->next_line = 0;

    // clear local pixel buffer
    memset(lcd->pix_buf, 0, LCD_PIX_BUF_BYTE_SIZE);
    memset(lcd->pix_buf2, 0, LCD_PIX_BUF_BYTE_SIZE);

    return lcd;
}

/// \method command(instr_data, buf)
///
/// Send an arbitrary command to the LCD.  Pass 0 for `instr_data` to send an
/// instruction, otherwise pass 1 to send data.  `buf` is a buffer with the
/// instructions/data to send.
STATIC mp_obj_t pyb_lcd_command(mp_obj_t self_in, mp_obj_t instr_data_in, mp_obj_t val) {
    pyb_lcd_obj_t *self = self_in;

    // get whether instr or data
    int instr_data = mp_obj_get_int(instr_data_in);

    // get the buffer to send from
    mp_buffer_info_t bufinfo;
    uint8_t data[1];
    pyb_buf_get_for_send(val, &bufinfo, data);

    // send the data
    for (uint i = 0; i < bufinfo.len; i++) {
        lcd_out(self, instr_data, ((byte*)bufinfo.buf)[i]);
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_3(pyb_lcd_command_obj, pyb_lcd_command);

/// \method contrast(value)
///
/// Set the contrast of the LCD.  Valid values are between 0 and 47.
STATIC mp_obj_t pyb_lcd_contrast(mp_obj_t self_in, mp_obj_t contrast_in) {
    pyb_lcd_obj_t *self = self_in;
    int contrast = mp_obj_get_int(contrast_in);
    if (contrast < 0) {
        contrast = 0;
    } else if (contrast > 0x2f) {
        contrast = 0x2f;
    }
    lcd_out(self, LCD_INSTR, 0x81); // electronic volume mode set
    lcd_out(self, LCD_INSTR, contrast); // electronic volume register set
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_lcd_contrast_obj, pyb_lcd_contrast);

/// \method light(value)
///
/// Turn the backlight on/off.  True or 1 turns it on, False or 0 turns it off.
STATIC mp_obj_t pyb_lcd_light(mp_obj_t self_in, mp_obj_t value) {
    pyb_lcd_obj_t *self = self_in;
    if (mp_obj_is_true(value)) {
        mp_hal_pin_high(self->pin_bl); // set pin high to turn backlight on
    } else {
        mp_hal_pin_low(self->pin_bl); // set pin low to turn backlight off
    }
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_lcd_light_obj, pyb_lcd_light);

/// \method write(str)
///
/// Write the string `str` to the screen.  It will appear immediately.
STATIC mp_obj_t pyb_lcd_write(mp_obj_t self_in, mp_obj_t str) {
    pyb_lcd_obj_t *self = self_in;
    size_t len;
    const char *data = mp_obj_str_get_data(str, &len);
    lcd_write_strn(self, data, len);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_lcd_write_obj, pyb_lcd_write);

/// \method fill(colour)
///
/// Fill the screen with the given colour (0 or 1 for white or black).
///
/// This method writes to the hidden buffer.  Use `show()` to show the buffer.
STATIC mp_obj_t pyb_lcd_fill(mp_obj_t self_in, mp_obj_t col_in) {
    pyb_lcd_obj_t *self = self_in;
    int col = mp_obj_get_int(col_in);
    if (col) {
        col = 0xff;
    }
    memset(self->pix_buf, col, LCD_PIX_BUF_BYTE_SIZE);
    memset(self->pix_buf2, col, LCD_PIX_BUF_BYTE_SIZE);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_lcd_fill_obj, pyb_lcd_fill);

/// \method get(x, y)
///
/// Get the pixel at the position `(x, y)`.  Returns 0 or 1.
///
/// This method reads from the visible buffer.
STATIC mp_obj_t pyb_lcd_get(mp_obj_t self_in, mp_obj_t x_in, mp_obj_t y_in) {
    pyb_lcd_obj_t *self = self_in;
    int x = mp_obj_get_int(x_in);
    int y = mp_obj_get_int(y_in);
    if (0 <= x && x <= 127 && 0 <= y && y <= 31) {
        uint byte_pos = x + 128 * ((uint)y >> 3);
        if (self->pix_buf[byte_pos] & (1 << (y & 7))) {
            return mp_obj_new_int(1);
        }
    }
    return mp_obj_new_int(0);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_3(pyb_lcd_get_obj, pyb_lcd_get);

/// \method pixel(x, y, colour)
///
/// Set the pixel at `(x, y)` to the given colour (0 or 1).
///
/// This method writes to the hidden buffer.  Use `show()` to show the buffer.
STATIC mp_obj_t pyb_lcd_pixel(size_t n_args, const mp_obj_t *args) {
    pyb_lcd_obj_t *self = args[0];
    int x = mp_obj_get_int(args[1]);
    int y = mp_obj_get_int(args[2]);
    if (0 <= x && x <= 127 && 0 <= y && y <= 31) {
        uint byte_pos = x + 128 * ((uint)y >> 3);
        if (mp_obj_get_int(args[3]) == 0) {
            self->pix_buf2[byte_pos] &= ~(1 << (y & 7));
        } else {
            self->pix_buf2[byte_pos] |= 1 << (y & 7);
        }
    }
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_lcd_pixel_obj, 4, 4, pyb_lcd_pixel);

/// \method text(str, x, y, colour)
///
/// Draw the given text to the position `(x, y)` using the given colour (0 or 1).
///
/// This method writes to the hidden buffer.  Use `show()` to show the buffer.
STATIC mp_obj_t pyb_lcd_text(size_t n_args, const mp_obj_t *args) {
    // extract arguments
    pyb_lcd_obj_t *self = args[0];
    size_t len;
    const char *data = mp_obj_str_get_data(args[1], &len);
    int x0 = mp_obj_get_int(args[2]);
    int y0 = mp_obj_get_int(args[3]);
    int col = mp_obj_get_int(args[4]);

    // loop over chars
    for (const char *top = data + len; data < top; data++) {
        // get char and make sure its in range of font
        uint chr = *(byte*)data;
        if (chr < 32 || chr > 127) {
            chr = 127;
        }
        // get char data
        const uint8_t *chr_data = &font_petme128_8x8[(chr - 32) * 8];
        // loop over char data
        for (uint j = 0; j < 8; j++, x0++) {
            if (0 <= x0 && x0 < LCD_PIX_BUF_W) { // clip x
                uint vline_data = chr_data[j]; // each byte of char data is a vertical column of 8 pixels, LSB at top
                for (int y = y0; vline_data; vline_data >>= 1, y++) { // scan over vertical column
                    if (vline_data & 1) { // only draw if pixel set
                        if (0 <= y && y < LCD_PIX_BUF_H) { // clip y
                            uint byte_pos = x0 + LCD_PIX_BUF_W * ((uint)y >> 3);
                            if (col == 0) {
                                // clear pixel
                                self->pix_buf2[byte_pos] &= ~(1 << (y & 7));
                            } else {
                                // set pixel
                                self->pix_buf2[byte_pos] |= 1 << (y & 7);
                            }
                        }
                    }
                }
            }
        }
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_lcd_text_obj, 5, 5, pyb_lcd_text);

/// \method show()
///
/// Show the hidden buffer on the screen.
STATIC mp_obj_t pyb_lcd_show(mp_obj_t self_in) {
    pyb_lcd_obj_t *self = self_in;
    memcpy(self->pix_buf, self->pix_buf2, LCD_PIX_BUF_BYTE_SIZE);
    for (uint page = 0; page < 4; page++) {
        lcd_out(self, LCD_INSTR, 0xb0 | page); // page address set
        lcd_out(self, LCD_INSTR, 0x10); // column address set upper; 0
        lcd_out(self, LCD_INSTR, 0x00); // column address set lower; 0
        for (uint i = 0; i < 128; i++) {
            lcd_out(self, LCD_DATA, self->pix_buf[128 * page + 127 - i]);
        }
    }
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_lcd_show_obj, pyb_lcd_show);

STATIC const mp_rom_map_elem_t pyb_lcd_locals_dict_table[] = {
    // instance methods
    { MP_ROM_QSTR(MP_QSTR_command), MP_ROM_PTR(&pyb_lcd_command_obj) },
    { MP_ROM_QSTR(MP_QSTR_contrast), MP_ROM_PTR(&pyb_lcd_contrast_obj) },
    { MP_ROM_QSTR(MP_QSTR_light), MP_ROM_PTR(&pyb_lcd_light_obj) },
    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&pyb_lcd_write_obj) },
    { MP_ROM_QSTR(MP_QSTR_fill), MP_ROM_PTR(&pyb_lcd_fill_obj) },
    { MP_ROM_QSTR(MP_QSTR_get), MP_ROM_PTR(&pyb_lcd_get_obj) },
    { MP_ROM_QSTR(MP_QSTR_pixel), MP_ROM_PTR(&pyb_lcd_pixel_obj) },
    { MP_ROM_QSTR(MP_QSTR_text), MP_ROM_PTR(&pyb_lcd_text_obj) },
    { MP_ROM_QSTR(MP_QSTR_show), MP_ROM_PTR(&pyb_lcd_show_obj) },
};

STATIC MP_DEFINE_CONST_DICT(pyb_lcd_locals_dict, pyb_lcd_locals_dict_table);

const mp_obj_type_t pyb_lcd_type = {
    { &mp_type_type },
    .name = MP_QSTR_LCD,
    .make_new = pyb_lcd_make_new,
    .locals_dict = (mp_obj_dict_t*)&pyb_lcd_locals_dict,
};

#endif // MICROPY_HW_HAS_LCD