PCD8544 display not working and wrong implementation of display contrast

[nobodyman1]

What happened?

I tried to use a PCD8544 display but it remains blank.
After testing #650 and a lot of investigation the display shows some data.
But I had to modify the code: Display.contrast = 255

To Reproduce Bug

Connections:

ESP32	PCD8544
IO13	DN (MOSI)
IO14	CLK
IO15	CS
IO22	DC
IO25	RESET

Expected Behavior

The range of display contrast in the webinterface is 0 ... 100%.
This value is used without any modification to set display contrast in the u8g2 library.
But I found in the u8g2 specification:
value : Contrast or brightness from 0 to 255

Install Method

Self-Compiled

What git-hash/version of OpenDTU?

055eb3a

Relevant log/trace output

No response

Anything else?

No response

[tbnobody]

Display should be fixed in 2e33f5c

[dAjaY85]

Nokia don't support contrast change, if contrast is setted, display stays off. In this case, I implemented in my fork, if contrast is 255, the contrast will not setted.

[tbnobody]

According to the data sheet it does support setting the contrast. Even the library supports it: https://github.com/olikraus/u8g2/blob/4d9f63394f070a9f6e079ae8bccb97bad5967481/csrc/u8x8_d_pcd8544_84x48.c#L124

With my patch above the contrast value from 0...100 is spread from 0...255... But if it's still not working there is maybe a mistake in the display library. will doublecheck this later.

[dAjaY85]

I have testet it, without backlights, maybe with contrast you can adjust the blacklights?

[ms-doneck]

Could someone please be so kind and describe the connection of this display, including pin mapping, under doc2/Display.md and docs/DeviceProfiles?

[nobodyman1]

I tried firmware version d508b41.

build_flags = ${env.build_flags}
    -DHOYMILES_PIN_MISO=19
    -DHOYMILES_PIN_MOSI=23
    -DHOYMILES_PIN_SCLK=18
    -DHOYMILES_PIN_IRQ=26
    -DHOYMILES_PIN_CE=21
    -DHOYMILES_PIN_CS=5
    -DDISPLAY_TYPE=1
    -DDISPLAY_DATA=22 ; D/C
    -DDISPLAY_CS=15
    -DDISPLAY_RESET=25

Display connections

ESP32	PCD8544
IO23	DN (MOSI)
IO18	CLK
IO15	CS
IO22	DC
IO25	RESET

The display shows some text (OpenDTU!) but the contrast setting is very bad.
If I try to change the default contrast (which is 60%) to another value and press the save button an error message is shown:
Profil muss zwischen 1 und 63 Zeichen lang sein!

After uploading pin_configuration.json with exact same settings as configured with build_flags it was possible to change the display contrast.
If I set the value to 50% the display contrast is ok!

[ms-doneck]

Today I'm back home and checked your settings - yes it's working, but I only see "OpenDTU!" msg with good contrast at 50%.
But how to see the live data?
On the web interface I can see that my HM600 is producing fine.

[nobodyman1]

Today I'm back home and checked your settings - yes it's working, but I only see "OpenDTU!" msg with good contrast at 50%. But how to see the live data? On the web interface I can see that my HM600 is producing fine.

I´m sorry, I only prepared my OpenDTU but I don´t have a Hoymiles device to test.

[ms-doneck]

You don't need an Hoymiles. The display must change to "offline" inside the loop, but it stays "frozen" with the "OpenDTU!" text from setStartupDisplay().

The loop is running fine and an I2C display works. But the PCD8544 in dead inside the loop.

I wrote some text to all lines inside setStartupDisplay() > works!
I did the same inside the loop, > doesn't work > still "OpenDTU!" :-(

When I change the displays constructor to use software SPI:
U8G2_PCD8544_84X48_F_4W_SW_SPI(U8G2_R0, 14, 12, cs, data, reset);
It's working fine - but I'd need an option for the two addional pins and the font isn't a beauty...

[nobodyman1]

v24.4.6 seems to work without any modification.
Thanks a lot!!

The date output in the last line doesn´t look very nice. It would be better to have hours and minutes instead of the day (%a).

[dAjaY85]

Please look at the implementation of the displays at the ahoy Projekt. This steps are already done there.

Would be nice, if OpenDTU will get the same state with the displays like Ahoy. Code is there, need smaller adjustments.

If the implementation is needed, I can send a new PR.

[ms-doneck]

Here it's already running fine. I'm not very familar using GIT, so I add the files here. Use it as you like.
I did some renaming in the displays constructor to clearfy the pin names and I also did a pin-mapping file and some sketches.
I changed the date time format to "%d.%m.%y %T" if its not a "large" display.

The reset pin is not needed - so I used ths for the DC pin.

platformio_override.ini:

[env:esp32_pcd8455]
board = esp32dev
build_flags = ${env.build_flags}
    -DHOYMILES_PIN_MISO=19
    -DHOYMILES_PIN_MOSI=23
    -DHOYMILES_PIN_SCLK=18
    -DHOYMILES_PIN_IRQ=16
    -DHOYMILES_PIN_CE=4
    -DHOYMILES_PIN_CS=5
    -DDISPLAY_TYPE=1
    -DDISPLAY_DATA=12  ; DIN 
    -DDISPLAY_CLK=14   ; CLK
    -DDISPLAY_CS=26    ; CE
    -DDISPLAY_RESET=13 ; DC

changes.zip

[dAjaY85]

look here:
https://github.com/dAjaY85/OpenDTU