WaveShare 1.3" OLED driving by I²C

Projects Programming
1

Hi everybody,

I have bought three of these WaveShare 1.3" OLED 64 x 128 Pixel displays
grafik

On the backside there seems to be two solderpads for configuring either SPI or I²C

grafik
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I did test the display successfully in SPI mode with this wiring

grafik
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taken from this website

Then I tried to test I²C-mode.
First of all I had a hard time to find where to change the configuration

The demo-code https://www.waveshare.com/w/upload/3/37/1.3inch_OLED_Module_C_code.7z

uses a lot of tabs
in the file DEV_Config.h

#define USE_SPI_4W  1
#define USE_IIC     0

for using I²C it has to be changed to opposite values

#define USE_SPI_4W  0
#define USE_IIC     1

input-pins are described here

grafik
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So for testing with I²C-interface I connected to two opened solderpads
grafik

But it did not work
The schematic show this which I don't understand
grafik

On the PCB there is a SMD-resistor soldered between middle-pad and the right pad.
Would switching to I²C-mode require to de-solder the SMD-resistor and to re-solder the SMD-resistor between middle-pad and left-pad?

What do they think at WaveShare? Am I supposed to have a hotair SMD soldering equipment?

Did anybody got it to work in I²C-mode?

best regards Stefan

1 Like
2

The resistor is likely 0 ohms. So, you could use a short stub of wire or perhaps even a solder blob.

I can't really tell scale from your pictures. But, I've found that down to 0402 size is manageable even for a ham-fisted old guy like me with a hobbyist-quality soldering iron. I have a tech at work (same age as me) who can handle much smaller using a professional soldering station and a high-quality microscope.

3

Removal:

apply the iron on top of the part. Apply solder generously, so the whole thing is covered in solder. Lift. The part will stick to the iron. If not, use a little sideways "flick".

Application:

With tweezers, hold the part in place and heat one end until it sticks (I'm assuming there is already some solder on the pads). Solder the other end. Return to the first end and re-solder.

4

Hi gfvavlo and aarg,

thank you for answering. I finally got it to work through removing the zero-ohm-resistor and applying a solder-blob from left pad to middle-pad to the I²C / SPI config-pads

Though something is still very strange. To make it work I have to connect the Arduino-Uno-IO-pin 13 to the RESET-input of the display. If I run the demo-sketch the onboard LED (IO-pin 13) is ON. As soon as I want to connect the plus-wire of my DMM the onboard-LED goes off and the display isn't working. Huh? What's that??

I'm very curious if/what the manufacturer WaveShare will "share" for "wavy"-informations about this.

best regards Stefan

5

You can't look at that small section of the schematic in isolation. Here is a bigger piece of it which shows where IM is connected. I guess, from the markings, that is the solder jumper / or zero ohm resistor bridge.

image
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