ssd1306 v0.1.0

Minimal SSD1306 128x64 I2C command and page-write driver.

Application scenarios

• A status display for voltage, mode, or fault codes.
• A small menu on a product with one OLED.
• A bring-up display during manufacturing test.

Contract

typedef struct {
    void *context;
    uint8_t (*write)(void *context, uint8_t control, const uint8_t *data, uint16_t length);
} ssd1306_port_t;

void ssd1306_init(ssd1306_port_t port);
void ssd1306_clear(ssd1306_port_t port);
void ssd1306_set_contrast(ssd1306_port_t port, uint8_t value);
void ssd1306_write_page(ssd1306_port_t port, uint8_t page, uint8_t column,
                        const uint8_t *data, uint8_t width);

• write sends one I2C transaction: control = 0x00 for commands, 0x40 for GDDRAM data.
• init sends the 128x64 charge-pump and addressing sequence.
• clear fills all eight pages with zeros.
• write_page writes one page (8 pixels high) from column.
• The caller owns the page buffer; no framebuffer or font is included.

Parameters

• I2C address 0x3C or 0x3D is selected in the adapter.
• width must fit column + width <= 128.
• Contrast 0..255; 0xCF is a common start.

Memory and timing

• 8 bytes of state plus the port context.
• clear sends 1024 data bytes; split into adapter-sized chunks.

Integration

ssd1306_port_t port = board_ssd1306_port();
ssd1306_init(port);
ssd1306_clear(port);
uint8_t row[128] = {0};
row[0] = 0x3C;
ssd1306_write_page(port, 2, 0, row, 128);

Adapters

• Keep the I2C address, bus speed, and reset pin in the adapter.
• Reference: u8g2 u8x8_d_ssd1306_128x64_noname.c (BSD-2-Clause).
• The init sequence is hardware-specific; verify the panel's charge pump.

When not to use

• A different controller (SH1106, SSD1309) needs a different init sequence.
• Text and graphics; add a font/renderer above this page API.

Verification

make test covers the init command stream, clear pages, contrast, and a page write.

void *context;
uint8_t (*write)(void *context, uint8_t control, const uint8_t *data, uint16_t length);