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Add SSD1315 driver (128x64 OLED screen via I2C)
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This is the screen that comes with the Grove Beginner Kit. To work
with the 328p's memory limitations, this driver creates a half-scale
bitmap and then expands it.

Signed-off-by: Keith Packard <keithp@keithp.com>
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keith-packard committed Feb 5, 2021
1 parent 2138e25 commit 598066b
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21 changes: 21 additions & 0 deletions snek-draw.builtin
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#
# Copyright © 2021 Keith Packard <keithp@keithp.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
#
draw.erase, 0
draw.color, 1
draw.line, 2
draw.move, 2
264 changes: 264 additions & 0 deletions snek-ssd1315.c
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/*
* Copyright © 2021 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/

#include "snek.h"
#include "snek-i2c.h"

/* SSD1315 128x64 OLED display */

#define SSD_ADDR 0x78

#define SSD_COLUMN_LO(x) (0x00 | (x))
#define SSD_COLUMN_HI(x) (0x10 | (x))
#define SSD_SET_ADDR_MODE 0x20 /* + 1 byte */
#define SSD_SET_COLUMN_ADDR 0x21 /* + 2 bytes */
#define SSD_SET_PAGE_ADDR 0x22 /* + 2 bytes */
#define SSD_SET_START_LINE(x) (0x40 | (x))
#define SSD_SET_CONTRAST 0x81 /* + 1 byte */
#define SSD_SET_SEG_REMAP(x) (0xa0 | (x))
#define SSD_ENTIRE_ON(x) (0xa4 | (x))
#define SSD_SET_INVERSE(x) (0xa6 | (x))
#define SSD_SET_MUX 0xa8 /* + 1 byte */
#define SSD_DISPLAY_ON(x) (0xae | (x))
#define SSD_SET_PAGE_START(x) (0xb0 | (x))
#define SSD_COM_OUTPUT_SCAN(x) (0xc0 | ((x) << 3))
#define SSD_SET_VERT_SHIFT 0xd3 /* + 1 byte */
#define SSD_SET_CLOCK_DIV 0xd5 /* + 1 byte */
#define SSD_SET_PRECHARGE 0xd9 /* + 1 byte */
#define SSD_SET_PIN_CONFIG 0xda /* + 1 byte */
#define SSD_SET_COM_VOLTAGE 0xdb /* + 1 byte */
#define SSD_NOP 0xe3
#define SSD_CHARGE_PUMP 0x8d /* + 1 byte */
#define SSD_SCROLL_H(x) (0x26 | (x)) /* + 6 bytes */
#define SSD_SCROLL_V(x) (0x29 | (x)) /* + 7 bytes */
#define SSD_SCROLL_STOP 0x2e
#define SSD_SCROLL_START 0x2f
#define SSD_SCROLL_AREA_V 0xa3 /* + 2 bytes */
#define SSD_SCROLL_SETUP(x) (0x2c | (x)) /* + 6 bytes */
#define SSD_SET_FADE 0x23 /* + 1 byte */
#define SSD_SET_ZOOM 0xd6 /* + 1 byte */

static const PROGMEM uint8_t setup[] = {
0x00,
SSD_DISPLAY_ON(0), /* display off */
SSD_SET_START_LINE(0),
SSD_SET_CONTRAST, 0x7f,
SSD_SET_INVERSE(0),
SSD_SET_MUX, 0x3f,
SSD_SET_SEG_REMAP(0),
SSD_COM_OUTPUT_SCAN(0),
SSD_SET_VERT_SHIFT, 0x00,
SSD_SET_CLOCK_DIV, 0x80,
SSD_SET_PRECHARGE, 0x22,
SSD_SET_PIN_CONFIG, 0x12,
SSD_SET_COM_VOLTAGE, 0x20,
SSD_CHARGE_PUMP, 0x15,
SSD_SCROLL_STOP,
SSD_DISPLAY_ON(1), /* display on */
};

#define SETUP_LEN (sizeof setup)

#define SCALE 2

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define PAGE_HEIGHT 8
#define FB_WIDTH (SCREEN_WIDTH / SCALE)
#define FB_HEIGHT (SCREEN_HEIGHT / SCALE)
#define FB_STRIDE ((FB_WIDTH + 7) / 8)
#define BITS ((1 << SCALE) - 1)

uint8_t fb[FB_STRIDE * FB_HEIGHT];

static uint8_t *
bit_addr(uint8_t x, uint8_t y)
{
return fb + y * FB_STRIDE + (x >> 3);
}

static void
ssd_start(uint8_t mode)
{
snek_i2c_start(SSD_ADDR | SNEK_I2C_WRITE);
snek_i2c_write(mode);
}

static void
ssd_start_write(uint8_t col, uint8_t page)
{
ssd_start(0x00);
snek_i2c_write(SSD_COLUMN_HI(col >> 4));
snek_i2c_write(SSD_COLUMN_LO(col & 0xf));
snek_i2c_write(SSD_SET_PAGE_START(page));
snek_i2c_stop();

ssd_start(0x40);

}

static void
paint_block(uint8_t x, uint8_t y)
{
uint8_t page = y / (PAGE_HEIGHT / SCALE);
uint8_t col = x * SCALE;
uint8_t c;

ssd_start_write(col, page);
y &= ~((PAGE_HEIGHT / SCALE) - 1);
uint8_t *p = bit_addr(x, y);
uint8_t bit = 1 << (x & 7);
uint8_t bits = BITS;
uint8_t b = 0;
for (c = 0; c < PAGE_HEIGHT / SCALE; c++) {
if (*p & bit)
b |= bits;
p += FB_STRIDE;
bits <<= SCALE;
}
for (c = 0; c < SCALE; c++)
snek_i2c_write(b);
snek_i2c_stop();
}

static uint8_t color = 1;

static void
set_bit(uint8_t x, uint8_t y)
{
uint8_t *b = bit_addr(x, y);
uint8_t ix = x & 7;
uint8_t mask = (1 << ix);
*b = (*b & ~mask) | color << ix;
paint_block(x, y);
}

static bool been_here;

snek_poly_t
snek_builtin_draw_erase(void)
{
uint8_t page;
uint16_t i;

memset(fb, '\0', sizeof(fb));
for (page = 0; page < 8; page++) {
ssd_start_write(0, page);
for (i = 0; i < 1024; i++)
snek_i2c_write(0);
snek_i2c_stop();
}
return SNEK_NULL;
}

static void
snek_oled_init(void)
{
if (!been_here) {
been_here = true;
uint8_t i;
ssd_start(0x00);
for (i = 0; i < SETUP_LEN; i++)
snek_i2c_write(pgm_read_byte(&setup[i]));
snek_i2c_stop();
snek_builtin_draw_erase();
}
}

static int8_t
snek_get_coord(snek_poly_t c, uint8_t max)
{
snek_soffset_t v = snek_poly_get_soffset(c);
if (v < 0)
v = 0;
if (v > max)
v = max;
return v;
}

static int8_t
snek_get_x(snek_poly_t c)
{
return snek_get_coord(c, FB_WIDTH - 1);
}

static int8_t
snek_get_y(snek_poly_t c)
{
return snek_get_coord(c, FB_HEIGHT - 1);
}

static int8_t last_x, last_y;

snek_poly_t
snek_builtin_draw_color(snek_poly_t v)
{
color = !!snek_poly_get_soffset(v);
return SNEK_NULL;
}

snek_poly_t
snek_builtin_draw_line(snek_poly_t x, snek_poly_t y)
{
int8_t ix = snek_get_x(x);
int8_t iy = snek_get_y(y);

snek_oled_init();

int8_t dx = ix - last_x;
int8_t step_x = 1;
if (dx < 0) {
dx = -dx;
step_x = -1;
}
int8_t dy = iy - last_y;
int8_t step_y = -1;
if (dy > 0) {
dy = -dy;
step_y = 1;
}
int8_t len = dx;
if (-dy > dx)
len = -dy;

int8_t err = dx + dy;

for (;;) {
set_bit(last_x, last_y);
int8_t e2 = err * 2;
if (len-- == 0)
break;
if (e2 >= dy) {
err += dy;
last_x += step_x;
}
if (e2 <= dx) {
err += dx;
last_y += step_y;
}
}
return SNEK_NULL;
}

snek_poly_t
snek_builtin_draw_move(snek_poly_t x, snek_poly_t y)
{
last_x = snek_get_x(x);
last_y = snek_get_y(y);
return SNEK_NULL;
}

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