Add support for SH1106 OLED displays

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - USB plug & play support for MIDI interfaces.
   * You can now connect/disconnect USB MIDI devices at runtime and they will be used instead of the GPIO MIDI interface when present.
+- Support for SH1106 OLED displays - many thanks to @arananet for donating a screen!
 
 ### Changed
 

Kernel.mk

@@ -14,6 +14,7 @@ OBJS		:=	src/config.o \
 				src/lcd/hd44780.o \
 				src/lcd/hd44780fourbit.o \
 				src/lcd/hd44780i2c.o \
+				src/lcd/sh1106.o \
 				src/lcd/ssd1306.o \
 				src/lcd/synthlcd.o \
 				src/main.o \

include/config.h

@@ -61,6 +61,7 @@ public:
 		ENUM(None, none)                   \
 		ENUM(HD44780FourBit, hd44780_4bit) \
 		ENUM(HD44780I2C, hd44780_i2c)      \
+		ENUM(SH1106I2C, sh1106_i2c)        \
 		ENUM(SSD1306I2C, ssd1306_i2c)
 
 	CONFIG_ENUM(TSystemDefaultSynth, ENUM_SYSTEMDEFAULTSYNTH);

include/lcd/ssd1306.h

@@ -51,7 +51,7 @@ public:
 	virtual void Update(CMT32Synth& Synth) override;
 	virtual void Update(CSoundFontSynth& Synth) override;
 
-private:
+protected:
 	struct TFrameBufferUpdatePacket
 	{
 		u8 DataControlByte;
@@ -60,7 +60,7 @@ private:
 	PACKED;
 
 	void WriteCommand(u8 nCommand) const;
-	void WriteFrameBuffer() const;
+	virtual void WriteFrameBuffer(bool bForceFullUpdate = false) const;
 	void SwapFrameBuffers();
 	void SetPixel(u8 nX, u8 nY);
 	void ClearPixel(u8 nX, u8 nY);
@@ -83,4 +83,14 @@ private:
 	u8 m_nCurrentFrameBuffer;
 };
 
+class CSH1106 : public CSSD1306
+{
+public:
+	CSH1106(CI2CMaster* pI2CMaster, u8 nAddress = 0x3C, u8 nWidth = 128, u8 nHeight = 32, TLCDRotation Rotation = TLCDRotation::Normal);
+
+private:
+	void WriteData(const u8* pData, size_t nSize) const;
+	virtual void WriteFrameBuffer(bool bForceFullUpdate = false) const override;
+};
+
 #endif

sdcard/mt32-pi.cfg

@@ -272,14 +272,15 @@ polyphony = 256
 # your device via the i2c_lcd_address option. Consult its datasheet, or see
 # our documentation for tested models and their configurations.
 #
-# Values: none*, hd44780_4bit, hd44780_i2c, ssd1306_i2c
+# Values: none*, hd44780_4bit, hd44780_i2c, sh1106_i2c, ssd1306_i2c
 #
 # none:         No LCD
 # hd44780_4bit: Hitachi HD44780 or compatible (e.g. WS0010, RS0010) character
 #               LCD connected to GPIO pins in 4-bit mode (see documentation for
 #               pinout)
 # hd44780_i2c:  As above, but using an I2C "backpack"
-# ssd1306_i2c:  Small I2C-based OLED graphical display
+# sh1106_i2c:   Small I2C-based OLED graphical display (usually 1.3")
+# ssd1306_i2c:  Small I2C-based OLED graphical display (usually 0.96")
 type = none
 
 # Set the width of the LCD.

src/lcd/sh1106.cpp

@@ -0,0 +1,68 @@
+//
+// sh1106.cpp
+//
+// mt32-pi - A baremetal MIDI synthesizer for Raspberry Pi
+// Copyright (C) 2020-2021 Dale Whinham <daleyo@gmail.com>
+//
+// This file is part of mt32-pi.
+//
+// mt32-pi is free software: you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// mt32-pi is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+// details.
+//
+// You should have received a copy of the GNU General Public License along with
+// mt32-pi. If not, see <http://www.gnu.org/licenses/>.
+//
+
+#include "lcd/ssd1306.h"
+
+enum TSH1106Command : u8
+{
+	SetColumnAddressLow  = 0x00,
+	SetColumnAddressHigh = 0x10,
+	SetStartLine         = 0x40,
+	SetPageAddress       = 0xB0,
+};
+
+CSH1106::CSH1106(CI2CMaster *pI2CMaster, u8 nAddress, u8 nWidth, u8 nHeight, TLCDRotation Rotation)
+	: CSSD1306(pI2CMaster, nAddress, nWidth, nHeight, Rotation)
+{
+}
+
+void CSH1106::WriteFrameBuffer(bool bForceFullUpdate) const
+{
+	// Reset start line
+	WriteCommand(SetStartLine | 0x00);
+
+	const size_t nPages = m_nHeight / 8;
+	constexpr size_t nPageSize = 128;
+
+	// Copy framebuffer one page at a time
+	for (u8 nPage = 0; nPage < nPages; ++nPage)
+	{
+		const size_t nOffset = nPage * nPageSize;
+		const bool bNeedsUpdate = bForceFullUpdate || memcmp(&m_FrameBuffers[0].FrameBuffer[nOffset], &m_FrameBuffers[1].FrameBuffer[nOffset], nPageSize) != 0;
+
+		if (bNeedsUpdate)
+		{
+			WriteCommand(SetPageAddress | nPage);
+
+			// SH1106 displays have a 132x64 pixel memory, but most modules have a visible width of 128 centred on this buffer
+			WriteCommand(SetColumnAddressLow | 0x02);
+			WriteCommand(SetColumnAddressHigh | 0x00);
+
+			// Prefix this page's pixel data with a data control byte
+			u8 Buffer[nPageSize + 1] = { 0x40 };
+			memcpy(Buffer + 1, &m_FrameBuffers[m_nCurrentFrameBuffer].FrameBuffer[nOffset], nPageSize);
+
+			m_pI2CMaster->Write(m_nAddress, Buffer, sizeof(Buffer));
+
+		}
+	}
+}

src/lcd/ssd1306.cpp

@@ -210,14 +210,14 @@ void CSSD1306::WriteCommand(u8 nCommand) const
 	m_pI2CMaster->Write(m_nAddress, Buffer, sizeof(Buffer));
 }
 
-void CSSD1306::WriteFrameBuffer() const
+void CSSD1306::WriteFrameBuffer(bool bForceFullUpdate) const
 {
 	// Reset start line
 	WriteCommand(SetStartLine | 0x00);
 
 	// Compare two framebuffers
 	const size_t nFrameBufferSize = m_nWidth * m_nHeight / 8;
-	const bool bNeedsUpdate = memcmp(m_FrameBuffers[0].FrameBuffer, m_FrameBuffers[1].FrameBuffer, nFrameBufferSize) != 0;
+	const bool bNeedsUpdate = bForceFullUpdate || memcmp(m_FrameBuffers[0].FrameBuffer, m_FrameBuffers[1].FrameBuffer, nFrameBufferSize) != 0;
 
 	// Copy entire framebuffer
 	if (bNeedsUpdate)
@@ -450,7 +450,7 @@ void CSSD1306::Print(const char* pText, u8 nCursorX, u8 nCursorY, bool bClearLin
 	}
 
 	if (bImmediate)
-		WriteFrameBuffer();
+		WriteFrameBuffer(true);
 }
 
 void CSSD1306::Clear(bool bImmediate)
@@ -459,7 +459,7 @@ void CSSD1306::Clear(bool bImmediate)
 	memset(pFrameBuffer, 0, m_nWidth * m_nHeight / 8);
 
 	if (bImmediate)
-		WriteFrameBuffer();
+		WriteFrameBuffer(true);
 }
 
 void CSSD1306::SetBacklightEnabled(bool bEnabled)

src/mt32pi.cpp

@@ -116,6 +116,8 @@ bool CMT32Pi::Initialize(bool bSerialMIDIAvailable)
 		m_pLCD = new CHD44780FourBit(pConfig->LCDWidth, pConfig->LCDHeight);
 	else if (pConfig->LCDType == CConfig::TLCDType::HD44780I2C)
 		m_pLCD = new CHD44780I2C(m_pI2CMaster, pConfig->LCDI2CLCDAddress, pConfig->LCDWidth, pConfig->LCDHeight);
+	else if (pConfig->LCDType == CConfig::TLCDType::SH1106I2C)
+		m_pLCD = new CSH1106(m_pI2CMaster, pConfig->LCDI2CLCDAddress, pConfig->LCDWidth, pConfig->LCDHeight, pConfig->LCDRotation);
 	else if (pConfig->LCDType == CConfig::TLCDType::SSD1306I2C)
 		m_pLCD = new CSSD1306(m_pI2CMaster, pConfig->LCDI2CLCDAddress, pConfig->LCDWidth, pConfig->LCDHeight, pConfig->LCDRotation);
 
@@ -244,13 +246,15 @@ bool CMT32Pi::Initialize(bool bSerialMIDIAvailable)
 	CCPUThrottle::Get()->DumpStatus();
 	SetPowerSaveTimeout(pConfig->SystemPowerSaveTimeout);
 
-	// Attach LCD to synths
+	// Attach LCD to synths and clear
 	if (m_pLCD)
 	{
 		if (m_pMT32Synth)
 			m_pMT32Synth->SetLCD(m_pLCD);
 		if (m_pSoundFontSynth)
 			m_pSoundFontSynth->SetLCD(m_pLCD);
+
+		m_pLCD->Clear();
 	}
 
 	// Start audio