0420CW-AB3 I2C Talking, Display is off and low current drawn

Aresway

• February 09, 2015 12:35

I am currently working with the 0420CW-AB3 OLED using the I2C protocol. I was able to scan the I2C bus and locate the address for my screen and I am receiving ACK responses to my addressing and commands. Unfortunately my display remains turned off regardless of which commands I send.

As of right now the VDD line is only drawing 0.756 mA from my power source. I believe this is the current being used to run the chip talking on I2C. Does this mean my screen was damaged during my initial wiring/testing? There was one occasion where I tried to switch to 5V operating mode and put 5V on the VDD line by mistake instead of the REGVDD line (Actual voltage was 4.8V). This was only briefly, but could it have damaged the display?

Are there any test pins on the board I can use to check the voltage and current to the display?

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  Paul_B

  • February 09, 2015 14:09

  Hello,
  It is definitely possible that you may have damaged the display, however lets first rule out user error.
  
  Can you please answer the following questions:

  1. What value pull-up resistors are you using?
  2. When using VDD is REGVDD grounded?
  3. Does your initialization sequence match with what is listed in the datasheet.
  4. Finally, if possible can you please upload your code.

  
  Thanks!

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  Aresway

  • February 09, 2015 16:53

   

  Paul,
  
  Thank you for getting back to me. After reading your questions I was confident on all of them except the last one. The last one about the initialization got me looking through what I was doing. I am using a different library file than the one you posted to a recent topic that handled parallel, i2c, and spi. When I compared my current library with the one you posted I realized mine did not have a method to differentiate between command and data messages. I also realized that their "init" function only sent a command of 0x41 instead of the complete list from the datasheet. I added a data call and tweaked the library a bit more based on the library you posted in a different topic. My library was also use 0xFE in the command method instead of 0x00 as in the command method from the better library.
  
  My display is now running and I am able to operate it like normal.
  
  Thank you for pointing me in the right direction. I took the word of the first library's author without double checking the implementation of it.

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  Paul_B

  • February 10, 2015 07:39

  No problem, enjoy your display!

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