PmodOLED™ Reference Manual Revision: October 19, 2011 Note: This document applies to REV A of the board. 1300 NE Henley Court, Suite 3 Pullman, WA 99163 (509) 334 6306 Voice | (509) 334 6300 Fax Overview The PmodOLED features an SPI-controlled monochrome OLED display, perfect for embedded applications requiring small, complex visual output. Features include: • • • • a 128x32 pixel 0.9’’ WiseChip/Univision UG-23832HSWEG04 OLED graphic display panel standard SPI interface clock speeds of up to 10MHz internal display buffer Functional Description The PmodOLED uses a standard 12-pin connector to display output on a 128x32 pixel organic LED (OLED) panel. The graphic display panel uses the Solomon Systech SSD1306 display controller. An SPI interface is used to configure the display, as well as to send the bitmap data to the device. The PmodOLED displays the last image drawn on the screen until it is powered down or a new image is drawn to the display. Refreshing and updating is handled internally. Power Supply The PmodOLED has two field-effect transistors (FETs) that control the display’s two power supplies. The VDDC control toggles the power to the logic of the display. The VBATC control toggles the power to the OLED display itself. Doc: 502-222 These two pins have pull-up resistors that turn off their respective power supplies when they’re not being driven. These pins are configured as outputs and driven low to turn on the power supply. The PmodOLED has a particular poweron/power-off sequence that must be followed to prolong the life of the display. Power-on sequence: 1. Apply power to VDD. 2. Send Display Off command. 3. Initialize display to desired operating mode. 4. Clear screen. 5. Apply power to VBAT. 6. Delay 100ms. 7. Send Display On command. Power-off sequence: 1. Send Display Off command. 2. Power off VBAT. 3. Delay 100ms. 4. Power off VDD. page 1 of 2 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners. PmodOLED Reference Manual Interface The display has a D/C pin (display or command select) that determines whether bytes sent to the display are interpreted as commands or as display data. The D/C pin is set high for display buffer access and low for command access. The RES pin is used to reset the SSD1306 display controller. The RES pin is driven low for reset and driven high for normal operation. The low-going reset pulse must be a minimum of 3us (microseconds) in duration for the display controller to reset correctly. For more information on the OLED display interface, see the UG-2832HSWEG04 datasheet available online or from Univisio. The OLED display uses a compatible command set from the SSD1306 device. For more information, see the SSD1306 datasheet available at www.solomon-systech.com. The UG2832 display is a serial device that is accessed using SPI. It is a write-only device, so it is not possible to read the display buffer contents or status from the panel. The maximum SPI clock frequency is 10Mhz. The CS (Chip Select) pin has to be held low for the display to receive data over the SPI interface. Digilent has libraries for the PmodOLED that provide functions for initializing the display and rendering simple text and graphics onto the display. These libraries can be used as-is or as a starting point for a more sophisticated graphics library. They are available on the PmodOLED product page at www.digilentinc.com. Interface Connector Signal Description Interface Connector Signal Description Connector J1 Pin Signal 1 CS 2 SDIN 3 None 4 SCLK 7 D/C 8 RES 9 VBATC 10 VDDC 5, 11 GND 6, 12 VCC Description SPI Chip Select (Slave Select) SPI Data In (MOSI) Unused Pin SPI Clock Data/Command Control Power Reset VBAT Battery Voltage Control VDD Logic Voltage Control Power Supply Ground Power Supply www.digilentinc.com page 2 of 2 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.