This is the OLED display in question and this is the datasheet of the display. I am going to connect to it using I2C. The datasheet provides mostly understandable explanations for the pins as far as their usage in different communication modes (I2C,SPI,8 bit parallel etc.) goes.

These are a couple that I have trouble with: enter image description here

Both of these pins have mentions of their function when driving them using using "68XX-series and 80XX-series microcontroller". From the datasheet it seems they mean 8-bit parallel com:

enter image description here

The question is, should leave them floating when using I2C? Or is data read still dependent on the state of those pins. I assume not, but I'd like to hear from someone who has had actual experience with them.

  • \$\begingroup\$ Based on general experience : don't leave them floating. Use a high value resistor (like 47K but check the input leakage current specs in the datasheet) to pull them to whatever looks like the more harmless state ... probably high. \$\endgroup\$
    – user16324
    Mar 2, 2020 at 13:39
  • \$\begingroup\$ probably not good form to post excerpts stamped confidential to a public forum... even if you got them from a public place \$\endgroup\$
    – vicatcu
    Mar 2, 2020 at 13:43
  • \$\begingroup\$ @BrianDrummond Thanks, good advice. Just worried that maybe their actual state does count after all and I should tie them to a specific level \$\endgroup\$ Mar 2, 2020 at 13:47
  • \$\begingroup\$ @vicatcu Had that thought, but they have the datasheet publicly on their site, so I figured there was not much confidential there anymore. \$\endgroup\$ Mar 2, 2020 at 13:47

1 Answer 1


The question is, should leave them floating when using I2C?

Use this "ER-OLED0.96-1 Series Interfacing Document" from the display manufacturer's page which you linked.

It includes the following I2C interface schematic, which shows those two signals E/RD# and R/W# are both grounded when using I2C, as I've marked in red on this extract from that document:

I2C interface connections for OLED display

  • \$\begingroup\$ Turns out I'm blind/dumb after all. Thanks so much, saved me unnecessary headache due to my own foolishness \$\endgroup\$ Mar 2, 2020 at 14:06
  • \$\begingroup\$ @AnthropomorphousDodecahedron - No problem :-) The recommended connections aren't always obvious in the other documents that I've found for those displays. That document is helpful for all of the possible interface connections. \$\endgroup\$
    – SamGibson
    Mar 2, 2020 at 14:09

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