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DougieLawson
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Joined: Sun Jun 16, 2013 11:19 pm
Location: Basingstoke, UK
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Re: OLED 16x2 HD44780 woes

Sun Nov 12, 2017 3:05 am

It's all about timing, ensure you include a delay after every write operation.

This video https://youtu.be/cVdSc8VYVBM shows what you need although his GPIO wiring is different.

I use his wiring:
EN == GPIO16
RS == GPIO26
D7 == GPIO12
D6 == GPIO5
D5 == GPIO6
D4 == GPIO13
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rljones
Posts: 1
Joined: Tue Jul 17, 2018 10:14 pm

Re: OLED 16x2 HD44780 woes

Tue Jul 17, 2018 10:27 pm

Having just endured getting Midas OLED displays working with an FPGA design, I suggest the best thing you can do is to buffer the signals to be proper 5V levels.
We too would get random junk, especially if probing the signals or even touching them.

I know it hurts, but READ THE DATASHEET'S DC SPECIFICATIONS.
The OLED displays are CMOS style inputs, VIN high must be 0.8V x VDD - which 3.3V is very much not.
ie > 4V is required for a high

As the RPi is a 3V3 device, it's logic levels simply do not cut the mustard.

We used a 74HCT245 which accepts TTL logic levels in (good for RPi outputs) but drives healthy 0V / 5V signals out.

Damn thing works like a Trojan now.
Ultra reliable whereas flaky as get out without the extra buffer.

Note we fly open loop, do not read back the ready flag, just use delays.
If you do read the ready flag, you'll also need to buffer in the reverse direction to condition the 5V stuff back to 3V3 levels.
Possibly use another pin to read from?

nes_pi
Posts: 20
Joined: Mon Jun 25, 2018 1:35 am

Re: OLED 16x2 HD44780 woes

Wed Jul 25, 2018 3:31 am

Hi, sorry to bump this old thread, but i have a WS0010 16x2 LCD i'd like to use as well. I bought one of the SPI ones because it would run on fewer wires.

https://www.crystalfontz.com/product/cf ... cter-green

Does anyone have this working properly on their pi? I am looking to interface it permanently with a Zero W and then rack mount it to a panel with the display...

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