From 4ed15fae4266770974960d31090ada32dfa5ea83 Mon Sep 17 00:00:00 2001
From: JP Stringham <jp@bloomdigital.to>
Date: Mon, 29 Dec 2025 12:12:49 -0500
Subject: [PATCH] Updated for better use as a module

---
 src/graphics.rs        |   2 +-
 src/graphics/sprite.rs |   1 +
 src/sh1106.rs          | 126 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 src/sh1106.rs

diff --git a/src/graphics.rs b/src/graphics.rs
index 6504144..ce025bc 100644
--- a/src/graphics.rs
+++ b/src/graphics.rs
@@ -4,7 +4,7 @@ use sprite::*;
 
 pub struct GraphicsBuf {
     buffer: [u8; 8192],
-    sprites: [Sprite; 30],
+    pub sprites: [Sprite; 30],
     sprite_atlas: SpriteAtlas,
 }
 
diff --git a/src/graphics/sprite.rs b/src/graphics/sprite.rs
index 3480468..8389b03 100644
--- a/src/graphics/sprite.rs
+++ b/src/graphics/sprite.rs
@@ -25,6 +25,7 @@ impl Sprite {
 
 #[repr(u8)]
 #[derive(Copy, Clone)]
+#[allow(unused)]
 pub enum SpriteFlip {
     None = 0,
     Horizontal = 1,
diff --git a/src/sh1106.rs b/src/sh1106.rs
new file mode 100644
index 0000000..5fa2bca
--- /dev/null
+++ b/src/sh1106.rs
@@ -0,0 +1,126 @@
+use cortex_m::delay::Delay;
+use embedded_hal::i2c::I2c;
+use rp2040_hal::i2c::Error;
+
+use defmt as _;
+
+use crate::graphics::GraphicsBuf;
+
+#[allow(unused)]
+#[repr(u8)]
+#[derive(PartialEq, Copy, Clone)]
+pub enum SH1106Cmd {
+    SetColumnLo = 0,
+    SetColumnHi = 0x10,
+    DisplayInvert = 0xA6,
+    DisplayOnOff = 0xAE,
+    ColDirectionNorm = 0xC0,
+    ColDirectionRev = 0xC8,
+    SetPage = 0xB0,
+}
+
+pub const SH1106_I2C_ADDR: u8 = 0x78u8 >> 1;
+
+pub struct SH1106Dev {
+    ready: bool,
+}
+
+impl SH1106Dev {
+    pub fn new(delay: &mut Delay, mut i2c: &mut dyn I2c<Error = Error>) -> Self {
+        send_command(&mut i2c, &SH1106Cmd::DisplayOnOff, 0x00);
+        delay.delay_ms(100);
+        send_command(&mut i2c, &SH1106Cmd::DisplayInvert, 0);
+        send_command(&mut i2c, &SH1106Cmd::ColDirectionNorm, 0);
+
+        set_col(&mut i2c, 2);
+        set_page(&mut i2c, 0);
+        clr_screen(&mut i2c);
+        delay.delay_ms(500);
+        send_command(&mut i2c, &SH1106Cmd::DisplayOnOff, 0x01);
+
+        SH1106Dev { ready: true }
+    }
+
+    pub fn blit_framebuffer(&self, i2c: &mut dyn I2c<Error = Error>, gfx_buf: &GraphicsBuf) {
+        if !self.ready {
+            panic!("Attempted to use SSH1106 before initialized.");
+        }
+
+        let buf = gfx_buf.get_px_buffer();
+        // for each row of 8x8 pixels
+        for r in 0..8 {
+            set_page(i2c, r);
+            set_col(i2c, 2);
+            // for each cel of 8x8 pixels
+            for c in 0..16 {
+                let mut cel = [0u8; 8];
+
+                // so our x,y here would be r * 128 + c * 8
+
+                // start assembling the 8x8 cel
+                for x in 0..8 {
+                    let mut col_byte = 0u8;
+
+                    // for each row of the cel
+                    for y in 0..8 {
+                        let pix_x = (c as usize) * 8 + x;
+                        let pix_y = (r as usize) * 8 + y;
+                        col_byte |= buf[pix_y * 128 + pix_x] << y;
+                    }
+
+                    cel[x] = col_byte;
+                }
+
+                write_cel_pixels(i2c, &cel);
+            }
+        }
+    }
+}
+
+fn send_command(i2c: &mut dyn I2c<Error = Error>, command: &SH1106Cmd, data: u8) {
+    let mut writebuf: [u8; 2] = [0; 2];
+
+    writebuf[0] = 0b1000_0000;
+    writebuf[1] = (command.clone() as u8) | data;
+
+    match i2c.write(SH1106_I2C_ADDR, &writebuf) {
+        _ => (),
+    };
+}
+
+fn set_col(i2c: &mut dyn I2c<Error = Error>, col: u8) {
+    let col_lo = col & 0b0000_1111;
+    let col_hi = (col & 0b1111_0000) >> 4;
+
+    send_command(i2c, &SH1106Cmd::SetColumnLo, col_lo);
+    send_command(i2c, &SH1106Cmd::SetColumnHi, col_hi);
+}
+
+fn set_page(i2c: &mut dyn I2c<Error = Error>, page: u8) {
+    send_command(i2c, &SH1106Cmd::SetPage, page & 0b0000_0111);
+}
+
+fn clr_screen(i2c: &mut dyn I2c<Error = Error>) {
+    let mut writebuf = [0u8; 132 * 8 + 1];
+
+    writebuf[0] = 0b0100_0000;
+
+    for i in 0..8 {
+        match i2c.write(SH1106_I2C_ADDR, &writebuf) {
+            _ => (),
+        };
+
+        set_page(i2c, i);
+    }
+}
+
+fn write_cel_pixels(i2c: &mut dyn I2c<Error = Error>, data: &[u8]) {
+    let mut writebuf = [0b0100_0000u8; 9];
+
+    writebuf[0] = 0b0100_0000;
+    writebuf[1..].copy_from_slice(&data[0..8]);
+
+    match i2c.write(SH1106_I2C_ADDR, &writebuf) {
+        _ => (),
+    };
+}