The pins on these modules are not well marked, but the one on left is #1 and the pins increment in order until the one on the very right, #20

Power Pins

• Pin #1 is power and signal Ground
• Pin #2 is 3V Power In - provide 3V with 100-150mA current capability
• Pin #3 is not used, do not connect to anything

Signal Pins

• Pin #4 is DC - the data/command pin. This is a 3V logic level input pin and is used for both SPI and 8-bit connections
• Pin #5 is WR - the 8-bit write pin. This is a 3V logic level input pin and is used for 8-bit connections. Do not connect if using SPI
• Pin #6 is RD - the 8-bit read pin. This is a 3V logic level input pin and is used for 8-bit connections. Do not connect if using SPI
• Pin #7 is Data0 - this pin is the SPI Clock pin and the 8-bit data bit 0 pin. This is a 3V logic level input pin when used with SPI, and an input/output when used in 8-bit.
• Pin #8 is Data1 - this pin is the SPI Data In pin and the 8-bit data bit 1 pin. This is a 3V logic level input pin when used with SPI, and an input/output when used in 8-bit.
• Pins #9-14 are Data2-7 - Used for 8-bit mode. These is a 3V input/output when used in 8-bit. Do not connect if using SPI
• Pin #15 is CS - the chip select pin. This is a 3V logic level input pin and is used for both SPI and 8-bit connections
• Pin #16 is RESET - the reset pin. This is a 3V logic level input pin and is used for both SPI and 8-bit connections

Remaining Pins

• Pins #17-19 are not connected, do not use
• Pin #20 is the 'frame ground' pin and is connected to the metal case around the OLED, you can connect to ground or leave floating.