ER_OLEDM1_CH1115

Table of contents

• Overview
• Output
• Installation
• Hardware
• Software
  • API documentation
  • SPI
  • Buffer
  • Fonts
  • Bitmaps
  • User adjustments
  • Files
• Tested_MCU

Overview

• Name : ER_OLEDM1_CH1115
• Title : Library to support the ER-OLEDM1.09-1 OLED Display Module driven by the CH1115 controller for the Arduino eco-system.
• Description :

1. Arduino eco-system library.
2. Invert colour, vertical rotate, sleep, fade effect, horizontal scroll and contrast control functions supported.
3. 12 ASCII fonts included.
4. Graphics support included.
5. Multi Screen, single shared buffer mode.
6. Bitmaps supported.
7. Hardware & software SPI options

• Author: Gavin Lyons

• Light weight basic text version here at link..

Output

Output Screenshots, From left to right, top to bottom.

1. Full screen bitmap displayed
2. Shared Screen mode, screen divided into two Screens with one buffer, Frame rate per second demo.
3. Shared Screen mode, screen divided into two Screens with one buffer, clock demo.
4. Different size and type of fonts
5. Available ASCII font printed out 0-127
6. Extended ASCII font printed out 128-255
7. Font 1-4
8. Font 7

Installation

The library is included in the official Arduino library manger and the optimum way to install it is using the library manager which can be opened by the manage libraries option in Arduino IDE.

Hardware

CH1115 is a single-chip CMOS OLED driver with controller for organic light emitting diode dot-matrix graphic display system. CH1115 consists of 128 segments, 64 commons that can support a maximum display resolution of 128 X 64. It is designed for Common Cathode type OLED panel. ER-OLEDM1.09-1W-SPI is a White 1.09" OLED Display Panel with Breakout Board. This module is a combination of the two.(controller and OLED)

pin no	pin name	pin desc
1	Gnd	Ground
2	VCC	voltage supply
3	SCL	Serial clock input
4	SDA	Serial data input
5	RES	This pin is reset signal input. When the pin is low, initialization of the chip is executed.
6	DC	This pin is Data or Command control pin.
7	CS	This pin is chip select input. The chip is enabled for MCU comms when CS is pulled low

VCC The CH1115 controller chip is a 3.3V device but the ERM LCD module has a "662k" 3.3V regulator at back. So the ERM OLED module VCC will also run at 5V.

Logic lines The logic lines where always connected to 3.3 Volts logic during all testing of library. The system can also run at 5 volts logic, the manufacture has instructional videos connected to an Arduino Mega.

This wiring Diagram from the manufacturer datasheet showing hardware setup connected to a 3.3 volt system MCU.

Software

API documentation

The API (application programming interface) documentation is at link hosted on github pages and generated by Doxygen.

API URL

SPI

Hardware and software SPI. Two different class constructors. User can pick the relevant constructor, see examples files. Hardware SPI is recommended, far faster and more reliable but Software SPI allows for more flexible GPIO selection. When running Software SPI it may be necessary on very fast high frequency MCU's to change the ERMCH1115_HIGHFREQ_DELAY define, It is a microsecond delay by default it is at 0. All the hardware SPI settings are defined in the header file and can be easily changed if necessary.

Buffer

The library features a multi-screen shared buffer mode, In order to save data memory.

For example if user defines a buffer to cover the whole screen it takes 1024 bytes of data memory. Instead a user can create a buffer that covers half the screen for just 512 bytes then define two screens each pointing to the same buffer. The user uses the ERMCH1115_SharedBuffer Class objects to define each screen and the ActiveBufferPtr pointer to switch between each screen. Multiple screens of same size can be created so OLED screen can be divided into thirds or quarters saving even more memory. The disadvantage of this is the code is slightly more complicated and user can only write to one screen at a time. If user does not want to use multi screen mode they can simply just define ONE screen to cover entire OLED screen. See example files for more detail.

Fonts

Font data table:

num	enum name	Char size XbyY	ASCII range	Size bytes	Size Scale-able
1	$_Default	5x8	0-0x7F	635	Y
2	$_Thick	7x8	0x20-0x5A, no lowercase letters	406	Y
3	$_SevenSeg	4x8	0x20-0x7A	360	Y
4	$_Wide	8x8	0x20-0x5A, no lowercase letters	464	Y
5	$_Tiny	3x8	0x20-0x7E	285	Y
6	$_Homespun	7x8	0x20-0x7E	658	Y
7	$_Bignum	16x32	0x2D-0x3A ,0-10 - . / :	896	N
8	$_Mednum	16x16	0x2D-0x3A ,0-10 - . / :	448	N
9	$_ArialRound	16x24	0x20-0x7E	4608	N
10	$_ArialBold	16x16	0x20-0x7E	3072	N
11	$_Mia	8x16	0x20-0x7E	1520	N
12	$_Dedica	6x12	0x20-0x7E	1152	N

1. $ = CH1115Font
2. Fonts 1-6 are byte high(at text size 1) scale-able fonts, columns of padding added by SW.
3. Font 7-8 are large numerical fonts and cannot be scaled(just one size).
4. Fonts 9-12 Alphanumeric fonts and cannot be scaled(just one size)

Font Methods:

Font num	Method	Size parameter	Notes
1-6	drawChar	Y	draws single character
1-6	drawText	Y	draws character array
7-12	drawChar	N	draws single character
7-12	drawText	N	draws character array
1-12	print	~	Polymorphic print class which will print out many data types(arduino built in)

These functions return a enum( CH1115_Return_Codes_e), non-zero in event of an error, see API doc. By default only Font 1 is commented in and ready to go to save memory. So to use a non-default Font (2-12), two steps. Comment in the respective define at top of library header file ERM19264_UC1609_graphics_font.h in the USER FONT OPTION ONE section Call SetFontNum method and pass it name of respective font. eg SetFontNum(CH1115Font_Wide).

Bitmaps

There is a few different ways of displaying bitmaps,

Num	Method	Data addressing	Note
1	OLEDBitmap()	Vertical	Writes directly to screen , no buffer used.
2	OLEDBuffer()	Vertical	Mostly for internal use ... mostly
3	buffer init technique	Vertical	Can be used when initialising a buffer, splash screen
4	drawBitmap()	Vertical	default, setDrawBitmapAddr(true)
5	drawBitmap()	Horizontal	setDrawBitmapAddr(false)

The drawBitmap function will return an enum with an error code if an error occurs see API docs. See the bitmap example file for more details on each method. Bitmaps can be turned to data here at link .

User adjustments

When the user calls OLEDbegin() to start OLED they can specify a contrast setting from 0x00 to 0xFF. Datasheet says 0x80 is default. User can also change contrast on the fly. Screen can be disabled to enter a sleep type mode where OLED draws 500uA. Screen pixel colour can be inverted and also screen can be vertically rotated.

There is a "fade or breath display effect". Whose parameters(time brightness) can be adjusted by passing data to function see "OLEDfadeEffect" in API and datasheet for more details. default is 0x81.

There is a Horizontal scroll effect. Whose parameters: Time-interval , direction , mode, can be adjusted by passing data to function see "OLEDscrollSetup" in API and datasheet for details. defaults are : 6 frames , right , continuous mode.

Files

X = ER_OLEDM1_CH1115 in tables below

Src Files	Description
X.hpp	library header file
X.cpp	library source file
X_graphics.hpp	graphics header file
X_graphics.cpp	graphics source file
X_graphics_font.hpp	font file
X_graphics_font.cpp	font data file

The example files are setup for an arduino UNO/NANO

Examples files ino	Description
X_BITMAPS	Shows use of bitmaps
X_GRAPHICS	Tests use of graphics
X_FUNCTIONS	Shows misc functions: flip, scroll , rotate, invert etc
X_MBUF	Shows use of shared buffer mode
X_CLOCK	Shows use of shared buffer mode + clock demo
X_TEXT	Shows use of text and fonts, All Fonts must be enabled to work fully
X_SWSPI	Shows use of software SPI
X_HELLO	Hello world, basic use case

Tested_MCU

Tested on following MCUs. for the pin connections used during testing see extras folder, GPIO_MCU_used.txt file.

1. Arduino UNO & NANO v3
2. ESP8266
3. ESP32
4. STM32 "blue pill"
5. Arduino Uno R4 Minima