From c8d1093faab4f219437ae3c2f93a6dbdce5c1a73 Mon Sep 17 00:00:00 2001
From: Archie Hilton <archie.hilton1@gmail.com>
Date: Sun, 7 Jul 2024 21:18:03 +0100
Subject: [PATCH] Add i2c update function with some stop bit shenanigans

---
 src/framebuffer.hh | 25 ++++++++++++++++++-------
 src/main.cc        | 21 ++++++++++++++++-----
 src/main.hh        |  2 +-
 3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/src/framebuffer.hh b/src/framebuffer.hh
index 199c645..273273b 100644
--- a/src/framebuffer.hh
+++ b/src/framebuffer.hh
@@ -3,7 +3,9 @@
 #include <cstdint>
 #include <cstddef>
 
+#include <functional>
 #include <array>
+#include <span>
 
 namespace Framebuffer {
   class FramebufferListener {
@@ -26,20 +28,29 @@ namespace Framebuffer {
     static constexpr size_t ROWS = (FB_HEIGHT/ROW_HEIGHT);
     static constexpr size_t SIZE = FB_WIDTH * ROWS;
     std::array<uint8_t, SIZE> m_buffer;
-    FramebufferListener &m_listener;
+    std::function<void(std::span<uint8_t>)> m_listener_update;
 
     void update_listener() {
-      m_listener.update(0, 0, m_buffer.data(), m_buffer.size());
+      m_listener_update(m_buffer);
     }
 
   public:
-    Framebuffer(FramebufferListener &listener)
-    : m_listener(listener) {
+    Framebuffer(std::function<void(std::span<uint8_t>)> f)
+    : m_listener_update(f) {
     }
 
-    void fill(uint8_t val) { FrameBufferBase::fill(m_buffer.data(), m_buffer.size(), val); }
-    void putc(size_t x, size_t y, char c) { FrameBufferBase::putc(m_buffer.data(), ROW_HEIGHT, m_buffer.size(), x, y, c); }
-    void puts(size_t x, size_t y, const char *s) { FrameBufferBase::putc(m_buffer.data(), ROW_HEIGHT, m_buffer.size(), x, y, s); }
+    void fill(uint8_t val) { 
+      FrameBufferBase::fill(m_buffer.data(), m_buffer.size(), val); 
+      update_listener();
+    }
+    void putc(size_t x, size_t y, char c) { 
+      FrameBufferBase::putc(m_buffer.data(), ROW_HEIGHT, m_buffer.size(), x, y, c);
+      update_listener();
+    }
+    void puts(size_t x, size_t y, const char *s) {
+      FrameBufferBase::putc(m_buffer.data(), ROW_HEIGHT, m_buffer.size(), x, y, s);
+      update_listener();
+    }
     uint8_t *data() { return m_buffer.data(); }
     size_t size() { return m_buffer.size(); }
   };
diff --git a/src/main.cc b/src/main.cc
index 78ecc74..2a20dfb 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -3,6 +3,7 @@
 
 #include "hardware/gpio.h"
 #include "hardware/i2c.h"
+#include "hardware/regs/i2c.h"
 #include "pico/time.h"
 #include "pico/types.h"
 
@@ -16,7 +17,6 @@
 
 static bool failure = false;
 
-
 static uint8_t encoder_pos = 0;
 
 void irq_callback(uint gpio, uint32_t events) {
@@ -90,7 +90,7 @@ static void write_cmd(uint8_t cmd) {
 }
 
 ssd1306::ssd1306()
-  : m_frame_buffer(*this) {
+  : m_frame_buffer(std::bind(&ssd1306::update, this, std::placeholders::_1)) {
     write_cmd(SET_DISP | 0x00); // Off
 
     write_cmd(SET_MUX_RATIO); // The height
@@ -157,10 +157,21 @@ void ssd1306::flush() {
   }
 }
 
-void ssd1306::update(size_t x, size_t y, uint8_t *data, size_t len) {
-  set_coordinates(x, 128, y, 7);
+void ssd1306::update(std::span<uint8_t> data) {
+  set_coordinates(0, 128, 0, 7);
   write_cmd(SET_MEM_ADDR); 
   write_cmd(0x00); // Horizontal
 
-  // TODO: Something with nostop and then spitting raw bytes? might work...
+  uint8_t write = 0x40;
+  i2c_write_blocking(i2c0, ADDR, &write, 1, true);
+  i2c_write_raw_blocking(i2c0, data.data(), data.size()-1);
+
+  while (!i2c_get_write_available(i2c0)) tight_loop_contents();
+
+  // Write a stop bit with the final byte
+  i2c_get_hw(i2c0)->data_cmd = 1 << I2C_IC_DATA_CMD_STOP_LSB | data.data()[data.size()-1];
+
+  // https://github.com/raspberrypi/pico-sdk/issues/812#issuecomment-1983833379
+  // Wait for the stop bit to clock out
+  while (!(i2c0->hw->raw_intr_stat & I2C_IC_RAW_INTR_STAT_STOP_DET_BITS)) tight_loop_contents();
 }
diff --git a/src/main.hh b/src/main.hh
index 2fadd57..e94d895 100644
--- a/src/main.hh
+++ b/src/main.hh
@@ -35,6 +35,6 @@ public:
   void flush();
   void set_coordinates(uint8_t start_x, uint8_t end_x, uint8_t start_y, uint8_t end_y);
 
-  void update(size_t x, size_t y, uint8_t *data, size_t len);
+  void update(std::span<uint8_t> data);
 };