OLED C click

OLED C click lets you add a small but bright and crisp color OLED display to your design. It carries the PSP27801 OLED display, the same one that we have used on Hexiwear. The click is designed to run on 3.3V power supply only. It communicates with the target microcontroller over an SPI interface, and the following pins on the mikroBUS™ line: AN, INT, PWM and RST.

Small displays like these are ideal for displaying color icons, text or images.

Note: the previous version of the click, with the SEPS114A display driver and controller, is obsolete.

Display features

OLED displays are made from a thin film of organic compound that emits light when exposed to a current. They are bright, have a wide viewing angle and low power consumption.

PSP27801 OLED Display onboard the click has 96x96 px resolution and is capable of displaying 65K colors. It also has a wide viewing angle of 160º and an anti-glare polarizer to reduce reflection.

SSD1351 controller

The SSD1351 has embedded Graphic Display Data RAM (GDDRAM). It supports 8, 16, and 18 bits 8080/6800 parallel interface. This controller has 256-step contrast and 262K color control, giving a vivid color display on OLED panels.

The SSD1351 controller also has built in functionalities like vertical and horizontal scrolling, programmable frame rate and multiplex ratio, support for various color depths, etc.

Specification

Key features

• PSP27801 display
  • Panel matrix: 96x96
  • Color: 262K color and 65K colors
  • Driver IC: SSD1351
• Interface: SPI 
• 3.3V power supply

Pinout diagram

This table shows how the pinout on OLED C click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin	mikroBUStm				Pin	Notes
Read/Write	R/WC	1	AN	PWM	16	D/C	Data/Command
Reset	RST	2	RST	INT	15	EN	Enable
Chip select	CS	3	CS	TX	14	NC	Not connected
SPI clock	SCK	4	SCK	RX	13	NC	Not connected
Serial data output	SDO	5	MISO	SCL	12	NC	Not connected
Serial data input	SDI	6	MOSI	SDA	11	NC	Not connected
Power supply	+3.3V	7	3.3V	5V	10	NC	Not connected
Ground	GND	8	GND	GND	9	GND	Ground

Programming

The library covers all functionalities of the click board, on all mikroC compilers ( ARM, AVR, dsPIC, PIC, PIC32, FT90x ).

The demo shows how to properly initialize the SPI bus and use the following functions from the library:

•  fill screen
•  draw rectangle
•  draw line
•  write text
•  change brightness
•  draw image

Notes on the performance of the library

It is important to properly initialize the SPI bus.

CLOCK IDLE HIGH / RISING EDGE SAMPLING or so called MODE 3

If the SPI bus is not properly initialized, the same color will be displayed in few different tones, depending on how the SSD1351 sampled data from the SPI bus.

Power consumption depends on the screen contrast and the internal oscillator settings.

Code snippet

Proper SPI initialization on STM32 MCU (needed to get desired colors on the display)

01 void system_init()
02 {
03     GPIO_Digital_Output( &GPIOD_BASE, _GPIO_PINMASK_10 | _GPIO_PINMASK_13 );
04     GPIO_Digital_Output( &GPIOA_BASE, _GPIO_PINMASK_0 | _GPIO_PINMASK_4 );
05     GPIO_Digital_Output( &GPIOC_BASE, _GPIO_PINMASK_2 );
06     SPI3_Init_Advanced( _SPI_FPCLK_DIV4, _SPI_MASTER | _SPI_8_BIT |
07                         _SPI_CLK_IDLE_HIGH |  _SPI_SECOND_CLK_EDGE_TRANSITION |
08                         _SPI_MSB_FIRST | _SPI_SS_DISABLE | _SPI_SSM_ENABLE |
09 						_SPI_SSI_1, &_GPIO_MODULE_SPI3_PC10_11_12 );
10 }

Comparison table

The table below shows the difference between the old version of the click, that is now obsolete, and the new one with the PSP27801 display.