OLED - leakage current on I2C - change SCL to INPUT!?

Hi, i am running an OLED display (128x64) successfully via I2C. using a TAU Board - similar to Zero with SAMD21 cpu. using external pullup resistors on the I2C.

Problem: i am shutting down the display sometimes to save battery energy (basically working). a) if i use the sleep function of the display, i have 1mA leakage current from the 4k7 pullup to the display SDA. b) now i use a loadswitch to cut the powersupply of the display completely, but now i have a leakage current of 9mA on the SCL line, because SCL is high on the cpu side and the display SCL seems to be on GND level.

i tried to change the SCL Pin (17 on TAU) to INPUT (high resistance) in the code, but there is no change .. i am affraid that pin is not assigned in the way i suppose it is!? how can i switch the SCL pin to INPUT and back to SCL-function when i would like to turn on the OLED again.

thanks!

Can you post a schematic of how you are powering down this module please.

The Wire.begin() function sets SDA as input with internal pull-up and the Wire.end() function resets it back to INPUT. I'd try inserting Wire.end() before you power down the display and then Wire.begin() after you power it back up.

Instead of cutting the power to the LCD (which is more trouble in most cases) remove the pull up from the display. Use the internal pull up or switch to pull ups on the uC side with a higher value. You could make the pull ups switchable but don't know if the screen likes that.

septillion: Instead of cutting the power to the LCD (which is more trouble in most cases) remove the pull up from the display. Use the internal pull up or switch to pull ups on the uC side with a higher value. You could make the pull ups switchable but don't know if the screen likes that.

That is what I do. But I don't use an OLED display if I am trying to run a super-low power project (they're great though for text-heavy and graphic displays.) They use less current than a backlit LED display, but discrete LEDs can be turned completely off, with no current leakage. My favorite display module for low draw, textual devices is Adafruit's 4 x 14 segment backpack. When you turn it off, it's off.

I second Mike's request - show us what you got!