From e43fc343ac0897536114e360df5197e3fbc33542 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Mon, 30 May 2022 19:36:33 +0200
Subject: initial commit

---
 ssd1306.lua | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 ssd1306.lua

diff --git a/ssd1306.lua b/ssd1306.lua
new file mode 100644
index 0000000..54923bc
--- /dev/null
+++ b/ssd1306.lua
@@ -0,0 +1,61 @@
+local ssd1306 = {}
+
+local s_CONTRAST = 0x81
+local s_ENTIRE_ON = 0xa4
+local s_NORM_INV = 0xa6
+local s_DISP = 0xae
+local s_MEM_ADDR = 0x20
+local s_COL_ADDR = 0x21
+local s_PAGE_ADDR = 0x22
+local s_DISP_START_LINE = 0x40
+local s_SEG_REMAP = 0xa0
+local s_MUX_RATIO = 0xa8
+local s_COM_OUT_DIR = 0xc0
+local s_DISP_OFFSET = 0xd3
+local s_COM_PIN_CFG = 0xda
+local s_DISP_CLK_DIV = 0xd5
+local s_PRECHARGE = 0xd9
+local s_VCOM_DESEL = 0xdb
+local s_CHARGE_PUMP = 0x8d
+
+function ssd1306.wc(byte)
+	return ssd1306.wd({0x80, byte})
+end
+
+function ssd1306.wd(data)
+	i2c.start(0)
+	if not i2c.address(0, 0x3c, i2c.TRANSMITTER) then
+		return false
+	end
+	i2c.write(0, data)
+	i2c.stop(0)
+	return true
+end
+
+function ssd1306.init(width, height)
+	ssd1306.w = width
+	ssd1306.h = height
+	local tab = {s_DISP, s_MEM_ADDR, 0x01, s_DISP_START_LINE, s_SEG_REMAP + 0x01,
+		s_MUX_RATIO, height - 1, s_COM_OUT_DIR + 0x08, s_DISP_OFFSET, 0x00,
+		s_COM_PIN_CFG, height == 32 and 0x02 or 0x12, s_DISP_CLK_DIV, 0x80,
+		s_PRECHARGE, 0x88, s_VCOM_DESEL, 0x30, s_CONTRAST, 0x80, s_ENTIRE_ON,
+		s_NORM_INV, s_CHARGE_PUMP, 0x14, s_DISP + 0x01, s_COL_ADDR, 0, 127,
+		s_PAGE_ADDR, 0, 7}
+	for i, v in ipairs(tab) do
+		ssd1306.wc(v)
+	end
+
+	ssd1306.fb = string.rep("0", width * height / 8)
+end
+
+function ssd1306.show()
+	local txbuf = {0x40}
+	for i = 1, ssd1306.w * ssd1306.h / 8, 128 do
+		for j = 0, 127 do
+			txbuf[j+2] = string.byte(ssd1306.fb, i + j)
+		end
+		ssd1306.wd(txbuf)
+	end
+end
+
+return ssd1306
-- 
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