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Merged
bettio merged 1 commit into from
Jan 19, 2026
Merged

Add support for ssd1315 displays #11

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2 changes: 2 additions & 0 deletions display_driver.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,8 @@ Context *display_create_port(GlobalContext *global, term opts)
ctx = ili948x_display_create_port(global, opts);
} else if (!strcmp(compat_string, "solomon-systech,ssd1306")) {
ctx = ssd1306_display_create_port(global, opts);
} else if (!strcmp(compat_string, "solomon-systech,ssd1315")) {
ctx = ssd1306_display_create_port(global, opts);
} else if (!strcmp(compat_string, "sino-wealth,sh1106")) {
ctx = ssd1306_display_create_port(global, opts);
} else if (!strcmp(compat_string, "sitronix,st7789")
Expand Down
93 changes: 78 additions & 15 deletions ssd1306_display_driver.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,11 +53,18 @@
#define CMD_SET_COM_SCAN_MODE 0xC8
#define CMD_SET_CHARGE_PUMP 0x8D

typedef enum
{
DISPLAY_SSD1306,
DISPLAY_SSD1315,
DISPLAY_SH1106,
} display_type_t;

// TODO: let's change name, since also non SPI display are supported now
struct SPI
{
term i2c_host;
bool is_sh1106;
display_type_t type;
Context *ctx;
};

Expand Down Expand Up @@ -116,8 +123,9 @@ static void do_update(Context *ctx, term display_list)

i2c_master_write_byte(cmd, CTRL_BYTE_CMD_SINGLE, true);
i2c_master_write_byte(cmd, 0xB0 | ypos / 8, true);
if (spi->is_sh1106) {
// set the column, otherwise the starting column will be somewhere in the middle

if (spi->type == DISPLAY_SH1106 || spi->type == DISPLAY_SSD1315) {
// SSD1315 and SH1106 require explicit column address reset
i2c_master_write_byte(cmd, CTRL_BYTE_CMD_SINGLE, true);
i2c_master_write_byte(cmd, 0x00, true);
i2c_master_write_byte(cmd, CTRL_BYTE_CMD_SINGLE, true);
Expand All @@ -126,7 +134,7 @@ static void do_update(Context *ctx, term display_list)
i2c_master_write_byte(cmd, CTRL_BYTE_DATA_STREAM, true);


if (spi->is_sh1106) {
if (spi->type == DISPLAY_SH1106) {
// add 2 empty pages on sh1106 since it can have up to 132 pixels
// and 128 pixel screen starts at (2, 0)
i2c_master_write_byte(cmd, 0, true);
Expand All @@ -138,13 +146,13 @@ static void do_update(Context *ctx, term display_list)
}

// no need to send the last 2 page, the position will be set on next line again
// if (spi->is_sh1106) {
// if (spi->type == DISPLAY_SH1106) {
// i2c_master_write_byte(cmd, 0, true);
// i2c_master_write_byte(cmd, 0, true);
// }

i2c_master_stop(cmd);
i2c_master_cmd_begin(i2c_num, cmd, 10 / portTICK_PERIOD_MS);
i2c_master_cmd_begin(i2c_num, cmd, 100 / portTICK_PERIOD_MS);
i2c_cmd_link_delete(cmd);

memset(buf, 0, memsize);
Expand Down Expand Up @@ -176,17 +184,25 @@ static void display_init(Context *ctx, term opts)
ctx->platform_data = spi;

spi->ctx = ctx;
spi->type = DISPLAY_SSD1306; // Default to SSD1306

term compat_value_term = interop_kv_get_value_default(opts, ATOM_STR("\xA", "compatible"), term_nil(), ctx->global);
int str_ok;
char *compat_string = interop_term_to_string(compat_value_term, &str_ok);
if (str_ok && compat_string) {
spi->is_sh1106 = !strcmp(compat_string, "sino-wealth,sh1106");
free(compat_string);
} else {

if (!(str_ok && compat_string)) {
ESP_LOGE(TAG, "No Compatible Device Found.");
return;
}

if (!strcmp(compat_string, "sino-wealth,sh1106")) {
spi->type = DISPLAY_SH1106;
} else if (!strcmp(compat_string, "solomon-systech,ssd1315")) {
spi->type = DISPLAY_SSD1315;
}

free(compat_string);

int reset_gpio;
if (!display_common_gpio_from_opts(opts, ATOM_STR("\x5", "reset"), &reset_gpio, glb)) {
ESP_LOGI(TAG, "Reset GPIO not configured.");
Expand All @@ -209,11 +225,58 @@ static void display_init(Context *ctx, term opts)
i2c_master_write_byte(cmd, (I2C_ADDRESS << 1) | I2C_MASTER_WRITE, true);
i2c_master_write_byte(cmd, CTRL_BYTE_CMD_STREAM, true);

i2c_master_write_byte(cmd, CMD_SET_CHARGE_PUMP, true);
i2c_master_write_byte(cmd, 0x14, true);
if (spi->type == DISPLAY_SSD1315) {
/*
* Init sequence derived from u8g2 project (BSD-2-Clause).
* Source: https://github.com/olikraus/u8g2
*
* These values are standard hardware initialization commands
* defined by the Solomon Systech SSD1315 datasheet.
*/

i2c_master_write_byte(cmd, 0xAE, true); // Display OFF

i2c_master_write_byte(cmd, 0xD5, true); // Set Display Clock Divide Ratio / Oscillator Frequency
i2c_master_write_byte(cmd, 0x80, true); // 0x80 is standard/stable

i2c_master_write_byte(cmd, 0xA8, true); // Set Multiplex Ratio
i2c_master_write_byte(cmd, 0x3F, true); // 64 MUX

i2c_master_write_byte(cmd, 0xD3, true); // Set Display Offset
i2c_master_write_byte(cmd, 0x00, true); // No offset

i2c_master_write_byte(cmd, CMD_SET_SEGMENT_REMAP, true);
i2c_master_write_byte(cmd, CMD_SET_COM_SCAN_MODE, true);
i2c_master_write_byte(cmd, 0x40, true); // Set Display Start Line to 0

i2c_master_write_byte(cmd, 0x8D, true); // Set Charge Pump
i2c_master_write_byte(cmd, 0x14, true); // Enable Charge Pump

i2c_master_write_byte(cmd, 0xA1, true); // Set Segment Remap
i2c_master_write_byte(cmd, 0xC8, true); // Set COM Scan Mode

i2c_master_write_byte(cmd, 0xDA, true); // Set COM Pins Hardware Configuration
i2c_master_write_byte(cmd, 0x12, true); // Alternative COM pin config

i2c_master_write_byte(cmd, 0x81, true); // Set Contrast Control
i2c_master_write_byte(cmd, 0xCF, true); // Use High Contrast (0xCF) as per u8x8

i2c_master_write_byte(cmd, 0xD9, true); // Set Pre-charge Period
i2c_master_write_byte(cmd, 0xF1, true); // 0xF1 is required for stable 400kHz operation

i2c_master_write_byte(cmd, 0xDB, true); // Set VCOMH Deselect Level
i2c_master_write_byte(cmd, 0x40, true); // 0x40 (approx 0.77x VCC)

i2c_master_write_byte(cmd, 0xA4, true); // Resume to RAM content display
i2c_master_write_byte(cmd, 0xA6, true); // Normal Display (not inverted)

i2c_master_write_byte(cmd, 0xAD, true); // Internal IREF Setting
i2c_master_write_byte(cmd, 0x10, true); // Internal Iref
} else {
i2c_master_write_byte(cmd, CMD_SET_CHARGE_PUMP, true);
i2c_master_write_byte(cmd, 0x14, true);

i2c_master_write_byte(cmd, CMD_SET_SEGMENT_REMAP, true);
i2c_master_write_byte(cmd, CMD_SET_COM_SCAN_MODE, true);
}

if (invert) {
i2c_master_write_byte(cmd, CMD_DISPLAY_INVERTED, true);
Expand All @@ -224,7 +287,7 @@ static void display_init(Context *ctx, term opts)

esp_err_t res = i2c_master_cmd_begin(i2c_num, cmd, 50 / portTICK_PERIOD_MS);
if (res != ESP_OK) {
ESP_LOGE(TAG, "ssd1306 OLED configuration failed. error: 0x%.2X", res);
ESP_LOGE(TAG, "ssd1306/ssd1315 OLED configuration failed. error: 0x%.2X", res);
} else {
xTaskCreate(process_messages, "display", 10000, spi, 1, NULL);
}
Expand Down