Example board files for connecting "TinyScreen" - an arduino SSD1331 display from Tiny-Circuits

boards/addons/gdisp/board_SSD1331_tinyscreen_arduino.cpp

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+#include <Arduino.h>
+#include <SPI.h>
+#include <Wire.h>
+
+#include "board_SSD1331.h"
+
+#define LCD_BOARD_ID		0		// 0 or 1 - set by the position of a resistor near SX1505 (see schematic and board design)
+
+// GPIO Pins
+#define GPIO_DC				0x01
+#define GPIO_CS				0x02
+#define GPIO_RES			0x08
+#define GPIO_BTN1			0x10
+#define GPIO_BTN2			0x20
+#define GPIO_BTN3			0x40
+#define GPIO_BTN4			0x80
+#define GPIO_CMD_START		~(GPIO_CS|GPIO_DC)
+#define GPIO_DATA_START		~GPIO_CS
+#define GPIO_TRANSFER_END	GPIO_CS
+
+//GPIO Registers
+#define GPIO_RegData		0x00
+#define GPIO_RegDir			0x01
+#define GPIO_RegPullUp		0x02
+
+// Wire address of the SX1505 chip
+#define GPIO_ADDR			0x20
+
+static void writeGPIO(uint8_t regAddr, uint8_t regData)
+{
+  uint8_t oldTWBR=TWBR;
+  TWBR=0;
+  Wire.beginTransmission(GPIO_ADDR + LCD_BOARD_ID);
+  Wire.write(regAddr); 
+  Wire.write(regData);
+  Wire.endTransmission();
+  TWBR=oldTWBR;
+}
+
+static bool isDataMode = false;
+static bool isCmdMode = false;
+
+void SSD1331_init_board(void) {
+	//setup GPIO, reset SSD1331
+	writeGPIO(GPIO_RegData,~GPIO_RES);//reset low, CS/other pins high
+	writeGPIO(GPIO_RegDir,~GPIO_RES);//set reset to output
+	delay(5);
+	writeGPIO(GPIO_RegDir,~(GPIO_CS|GPIO_DC));//reset to input, CS/DC output
+	writeGPIO(GPIO_RegPullUp,GPIO_BTN1|GPIO_BTN2|GPIO_BTN3|GPIO_BTN4);//button pullup enable
+	//init SPI
+	SPI.begin();
+	SPI.setDataMode(SPI_MODE0);//wrong mode, works because we're only writing. this mode is compatible with SD cards.
+	SPI.setClockDivider(SPI_CLOCK_DIV2);
+	
+	isDataMode = isCmdMode = false;
+}
+
+void SSD1331_setpin_reset(int state) {
+	// Ignore this as we did it in the init_board
+}
+
+void SSD1331_aquirebus(void) {
+	// Do nothing as we do it in the data transfer
+}
+
+void SSD1331_releasebus(void) {
+	if (!isDataMode && !isCmdMode) return;
+	writeGPIO(GPIO_RegData,GPIO_TRANSFER_END);
+	isDataMode = isCmdMode = false;
+}
+
+void SSD1331_write_cmd(uint8_t cmd) {
+	if (!isCmdMode) {
+		writeGPIO(GPIO_RegData,GPIO_CMD_START);
+		isDataMode = false;
+		isCmdMode = true;
+	}
+	SPI.transfer(cmd);
+}
+
+void SSD1331_write_data(uint8_t data) {
+	if (!isDataMode) {
+		writeGPIO(GPIO_RegData,GPIO_DATA_START);
+		isDataMode = true;
+		isCmdMode = false;
+	}
+	SPI.transfer(data);
+}

boards/addons/gdisp/board_SSD1331_tinyscreen_arduino.h

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+/*
+ * This file is subject to the terms of the GFX License. If a copy of
+ * the license was not distributed with this file, you can obtain one at:
+ *
+ *              http://ugfx.org/license.html
+ */
+
+#ifndef _GDISP_LLD_BOARD_H
+#define _GDISP_LLD_BOARD_H
+
+#define init_board(g)			SSD1331_init_board()
+#define post_init_board(g)
+#define setpin_reset(g, state)	SSD1331_setpin_reset(state)
+#define acquire_bus(g)			SSD1331_aquirebus()
+#define release_bus(g)			SSD1331_releasebus()
+#define write_cmd(g, cmd)		SSD1331_write_cmd(cmd)
+#define write_data(g, data)		SSD1331_write_data(data)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void SSD1331_init_board(void);
+void SSD1331_setpin_reset(int state);
+void SSD1331_aquirebus(void);
+void SSD1331_releasebus(void);
+void SSD1331_write_cmd(uint8_t cmd);
+void SSD1331_write_data(uint8_t data);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _GDISP_LLD_BOARD_H */