ssd1306 driver sketch

3 files changed, 238 insertions, 0 deletions

diff --git a/src/pico1541.c b/src/pico1541.c
index e69de29..2c7ad35 100644
--- a/src/pico1541.c
+++ b/src/pico1541.c
@@ -0,0 +1,25 @@
+#include <hardware/i2c.h>
+#include <hardware/gpio.h>
+#include <pico/error.h>
+#include <pico/time.h>
+
+#include "ssd1306.h"
+
+int main() {
+  gpio_init(20);
+  gpio_init(21);
+  
+  gpio_set_function(20, GPIO_FUNC_I2C);
+  gpio_set_function(21, GPIO_FUNC_I2C);
+
+  gpio_set_pulls(20, true, false);
+  gpio_set_pulls(21, true, false);
+
+  i2c_init(i2c0, 400 * 1000);
+
+  ssd1306_t display;
+  ssd_init(&display, i2c0, 0x3C);
+  ssd_power_on(&display);
+  
+  return 0;
+}
diff --git a/src/ssd1306.c b/src/ssd1306.c
new file mode 100644
index 0000000..c766d5f
--- /dev/null
+++ b/src/ssd1306.c
@@ -0,0 +1,75 @@
+#include "ssd1306.h"
+
+#include <hardware/gpio.h>
+#include <pico/error.h>
+
+int ssd_init(ssd1306_t *display, i2c_inst_t *i2c, uint8_t addr) {
+  display->i2c = i2c;
+  display->addr = addr;
+  display->len = 0;
+
+  return PICO_OK;
+}
+
+int ssd_push(ssd1306_t *display, uint8_t byte) {
+  if (display->len < SSD1306_BUFFER_LEN) {
+    display->buf[display->len] = byte;
+    display->len++;
+    return PICO_OK;
+  } else {
+    return PICO_ERROR_BUFFER_TOO_SMALL;
+  }
+}
+
+int ssd_send(ssd1306_t *display) {
+  int ret = i2c_write_blocking(
+    display->i2c,
+    display->addr,
+    display->buf,
+    display->len,
+    false
+  );
+  display->len = 0;
+
+  return ret;
+}
+
+int ssd_power_on(ssd1306_t *display) {
+  ssd_push(display, SSD1306_CTRL_CMD);
+  
+  ssd_push(display, SSD1306_DISPLAY_OFF);
+  
+  ssd_push(display, SSD1306_SET_CLOCK_DIV);
+  ssd_push(display, 0x80);
+
+  ssd_push(display, SSD1306_SET_MULTIPLEX);
+  ssd_push(display, 0x1f);
+
+  ssd_push(display, SSD1306_START_LINE(0));
+
+  ssd_push(display, SSD1306_SET_CHARGE_PUMP);
+  ssd_push(display, SSD1306_CHARGE_PUMP_ON);
+
+  ssd_push(display, SSD1306_SET_MEMORY_MODE);
+  ssd_push(display, SSD1306_MEM_MODE_HORIZONTAL);
+
+  ssd_push(display, SSD1306_SEG_REMAP_COL127);
+  ssd_push(display, SSD1306_COM_SCAN_REMAP);
+  ssd_push(display, SSD1306_COM_PINS_SEQUENTIAL);
+
+  ssd_push(display, SSD1306_SET_CONTRAST);
+  ssd_push(display, 0xcf);
+
+  ssd_push(display, SSD1306_SET_PRECHARGE);
+  ssd_push(display, 0xf1);
+
+  ssd_push(display, SSD1306_SET_VCOMH);
+  ssd_push(display, SSD1306_VCOMH_0_77);
+
+  ssd_push(display, SSD1306_ENTIRE_DISPLAY_RESUME);
+  ssd_push(display, SSD1306_NORMAL_DISPLAY);
+  ssd_push(display, SSD1306_SCROLL_DEACTIVATE);
+  ssd_push(display, SSD1306_DISPLAY_ON);
+
+  return ssd_send(display);
+}
diff --git a/src/ssd1306.h b/src/ssd1306.h
new file mode 100644
index 0000000..7f6755e
--- /dev/null
+++ b/src/ssd1306.h
@@ -0,0 +1,138 @@
+#ifndef PICO1541_SSD1306_H
+#define PICO1541_SSD1306_H
+
+#include <stdint.h>
+#include <hardware/i2c.h>
+
+/* ------------------------------------------------------------------ */
+/* I2C addressing and control bytes                                    */
+/* ------------------------------------------------------------------ */
+#define SSD1306_I2C_ADDR            0x3C    /* 7-bit, SA0 = 0 (D/C# pin low) */
+#define SSD1306_I2C_ADDR_ALT        0x3D    /* 7-bit, SA0 = 1               */
+
+#define SSD1306_CTRL_CMD            0x00    /* following bytes are commands */
+#define SSD1306_CTRL_DATA           0x40    /* following bytes are GDDRAM   */
+#define SSD1306_CTRL_CMD_SINGLE     0x80    /* one command byte follows     */
+#define SSD1306_CTRL_DATA_SINGLE    0xC0    /* one data byte follows        */
+
+/* ------------------------------------------------------------------ */
+/* Fundamental commands                                                */
+/* ------------------------------------------------------------------ */
+#define SSD1306_SET_CONTRAST        0x81    /* 1 arg: 0x00..0xFF, reset 0x7F */
+#define SSD1306_ENTIRE_DISPLAY_RESUME 0xA4  /* output follows RAM (reset)    */
+#define SSD1306_ENTIRE_DISPLAY_ON   0xA5    /* all pixels on, ignores RAM    */
+#define SSD1306_NORMAL_DISPLAY      0xA6    /* 1 = pixel on                  */
+#define SSD1306_INVERSE_DISPLAY     0xA7    /* 1 = pixel off                 */
+#define SSD1306_DISPLAY_OFF         0xAE    /* sleep mode                    */
+#define SSD1306_DISPLAY_ON          0xAF
+
+/* ------------------------------------------------------------------ */
+/* Scrolling commands                                                  */
+/* ------------------------------------------------------------------ */
+#define SSD1306_SCROLL_RIGHT        0x26    /* 6 args: continuous, right     */
+#define SSD1306_SCROLL_LEFT         0x27    /* 6 args: continuous, left      */
+#define SSD1306_SCROLL_VERT_RIGHT   0x29    /* 5 args: vertical + horizontal */
+#define SSD1306_SCROLL_VERT_LEFT    0x2A    /* 5 args: vertical + horizontal */
+#define SSD1306_SCROLL_DEACTIVATE   0x2E
+#define SSD1306_SCROLL_ACTIVATE     0x2F
+#define SSD1306_SET_VERT_SCROLL_AREA 0xA3   /* 2 args: top fixed, scroll rows */
+
+/* Argument layout, 0x26 / 0x27:
+ *     dummy 0x00, start page, frame interval, end page, dummy 0x00, dummy 0xFF
+ * Argument layout, 0x29 / 0x2A:
+ *     dummy 0x00, start page, frame interval, end page, vertical offset
+ */
+
+/* ------------------------------------------------------------------ */
+/* Addressing commands                                                 */
+/* ------------------------------------------------------------------ */
+#define SSD1306_SET_MEMORY_MODE     0x20    /* 1 arg, see MODE_* below       */
+#define SSD1306_SET_COL_ADDR        0x21    /* 2 args: column start, end     */
+#define SSD1306_SET_PAGE_ADDR       0x22    /* 2 args: page start, end       */
+
+/* Page addressing mode only: start address is split across two commands. */
+#define SSD1306_SET_LOWER_COL_START 0x00    /* 0x00..0x0F = low nibble       */
+#define SSD1306_SET_HIGHER_COL_START 0x10   /* 0x10..0x1F = high nibble      */
+#define SSD1306_SET_PAGE_START      0xB0    /* 0xB0..0xB7 = page 0..7        */
+
+/* ------------------------------------------------------------------ */
+/* Hardware configuration                                              */
+/* ------------------------------------------------------------------ */
+#define SSD1306_SET_START_LINE      0x40    /* 0x40..0x7F, line 0..63        */
+#define SSD1306_SEG_REMAP_COL0      0xA0    /* column 0   -> SEG0 (reset)    */
+#define SSD1306_SEG_REMAP_COL127    0xA1    /* column 127 -> SEG0 (mirror X) */
+#define SSD1306_SET_MULTIPLEX       0xA8    /* 1 arg: N+1 rows, 0x0F..0x3F   */
+#define SSD1306_COM_SCAN_NORMAL     0xC0    /* COM0 -> COM[N-1]              */
+#define SSD1306_COM_SCAN_REMAP      0xC8    /* COM[N-1] -> COM0 (mirror Y)   */
+#define SSD1306_SET_DISPLAY_OFFSET  0xD3    /* 1 arg: shift 0..63 by COM     */
+#define SSD1306_SET_COM_PINS        0xDA    /* 1 arg, see COM_PINS_* below   */
+
+/* ------------------------------------------------------------------ */
+/* Timing and driving scheme                                           */
+/* ------------------------------------------------------------------ */
+#define SSD1306_SET_CLOCK_DIV       0xD5    /* 1 arg: lo = div-1, hi = freq  */
+                                            /*   reset 0x80                  */
+#define SSD1306_SET_PRECHARGE       0xD9    /* 1 arg: phase2/phase1          */
+                                            /*   reset 0x22, 0xF1 for ext VCC*/
+#define SSD1306_SET_VCOMH           0xDB    /* 1 arg, see VCOMH_* below      */
+#define SSD1306_NOP                  0xE3
+#define SSD1306_SET_CHARGE_PUMP     0x8D    /* 1 arg: 0x14 on, 0x10 off      */
+                                            /*   (SSD1306B / modules only)   */
+
+/* ------------------------------------------------------------------ */
+/* Parameter constants                                                 */
+/* ------------------------------------------------------------------ */
+#define SSD1306_MEM_MODE_HORIZONTAL 0x00
+#define SSD1306_MEM_MODE_VERTICAL   0x01
+#define SSD1306_MEM_MODE_PAGE       0x02    /* reset default */
+
+#define SSD1306_COM_PINS_SEQUENTIAL 0x02
+#define SSD1306_COM_PINS_ALTERNATIVE 0x12   /* 128x64 default */
+#define SSD1306_COM_PINS_SEQ_REMAP  0x22
+#define SSD1306_COM_PINS_ALT_REMAP  0x32
+
+#define SSD1306_VCOMH_0_65          0x00    /* ~0.65 x VCC */
+#define SSD1306_VCOMH_0_77          0x20    /* ~0.77 x VCC, reset */
+#define SSD1306_VCOMH_0_83          0x30    /* ~0.83 x VCC */
+
+#define SSD1306_CHARGE_PUMP_ON      0x14
+#define SSD1306_CHARGE_PUMP_OFF     0x10
+
+#define SSD1306_SCROLL_5_FRAMES     0x00    /* 5 frames per step   */
+#define SSD1306_SCROLL_64_FRAMES    0x01
+#define SSD1306_SCROLL_128_FRAMES   0x02
+#define SSD1306_SCROLL_256_FRAMES   0x03
+#define SSD1306_SCROLL_3_FRAMES     0x04
+#define SSD1306_SCROLL_4_FRAMES     0x05
+#define SSD1306_SCROLL_25_FRAMES    0x06
+#define SSD1306_SCROLL_2_FRAMES     0x07
+
+/* ------------------------------------------------------------------ */
+/* Helper macros for building command bytes                            */
+/* ------------------------------------------------------------------ */
+#define SSD1306_COL_ADDR_LO(c)      (uint8_t)(SSD1306_SET_LOWER_COL_START  | ((c) & 0x0F))
+#define SSD1306_COL_ADDR_HI(c)      (uint8_t)(SSD1306_SET_HIGHER_COL_START | (((c) >> 4) & 0x0F))
+#define SSD1306_PAGE(c)             (uint8_t)(SSD1306_SET_PAGE_START | ((c) & 0x07))
+#define SSD1306_START_LINE(l)       (uint8_t)(SSD1306_SET_START_LINE | ((l) & 0x3F))
+#define SSD1306_CONTRAST(v)         (uint8_t)(v)
+#define SSD1306_MUX_RATIO(rows)     (uint8_t)((rows) - 1)   /* rows = 16..64 */
+#define SSD1306_CLOCK(div, freq)    (uint8_t)((((freq) & 0x0F) << 4) | (((div) - 1) & 0x0F))
+
+#define SSD1306_BUFFER_LEN 256
+
+typedef struct ssd1306 {
+  i2c_inst_t *i2c;
+  uint8_t addr;
+
+  uint8_t buf[SSD1306_BUFFER_LEN];
+  size_t len;
+} ssd1306_t;
+
+int ssd_init(ssd1306_t *display, i2c_inst_t *i2c, uint8_t addr);
+
+int ssd_push(ssd1306_t *display, uint8_t byte);
+int ssd_send(ssd1306_t *display);
+
+int ssd_power_on(ssd1306_t *display);
+
+#endif