Francesco Adamo

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8 years, 8 months ago.

SSD1306 Display (OLED) with FRDM-K64F and FRDM-K25Z

Hi all,

I am trying to make a 0.96" SSD1306-based WaveShare's OLED display (http://www.wvshare.com/product/0.96inch-OLED-B.htm) to work with my FRDM-K64F to display some data from an I2C pressure sensor; I use the porting of Adafruit's SSD1306 library made for mbed by Neal Horman; I use the display in SPI mode.

My circuit works great when I use the FRDM-K25Z (data is displayed regularly on the display) but, when I recompile the code for the FRDM-K64F the display doesn't work at all (it is all black), but all other features of the circuit work regularly.

I used a mixed signal oscilloscope to explore the display signals and I discovered that when I use the FRDM-K64F, the MOSI signal (PTD2) appears to be very "weak" (only about 20 mV peak) and/or very distorted when it is connected to the DIN line of the display; however, if I disconnect the MOSI signal from the DIN line of the display and observe it again with the oscilloscope, its amplitude is regular. All other display signals (CLK, CS, DC, RESET) are regular.

I observe this problem only with the FRMD-K64F; from the board schematics there is not any additional series/parallel load connected to the PTD2.

Is there someone else that has used this kind of display with the K64F and that can give me some hint to solve this problem?

Hi,

Have you managed to solve this problem yet? I have a feeling that this is the case for my K64F as well although I won't know for sure until I next have access to an oscilloscope.

posted by Dan Tomlinson 16 Mar 2016

Hi,

at last I solved the problem and I discovered that it was related to a strange (and undocumented) behaviour of the DIN line of the display module; you can see the complete description of the debug process here: https://community.freescale.com/thread/366135.

Cheers

posted by Francesco Adamo 17 Mar 2016
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