One line more then expected

[thErZAgH]

Hi.

I looked into the code. But I don't know where the place for y (start)position is. Sometimes the white bar creates a new line at the upper screen. The 16th line of the bar, maybe.

https://www.forum64.de/index.php?thread/81832-neue-laufwerksemulation-pi1541/&postID=1272547#post1272547

Seems like the screen don't starts at y=0. It starts at 1 instead?

[pi1541]

I can't reproduce it on my screen.

[penfold42]

I did see it previously- possibly before I moved the i2c pins.

What i2c pins are you using ?
If using 27/28 Have you added pull-up resistors ?

[thErZAgH]

27/28 /wout pull-up.

Other guys have this phaenomena, too. Problem is: I cannot see a rule when this happens. It happes, yes. I tried a few times. But could not see why this happens...

Hmmmm....

[penfold42]

I2c corruption due to insufficient pull up resistors.

The cheap Ebay displays don’t have them and the pi doesnt on 27/28.
The Pi does have them on the other i2c bus.

[thErZAgH]

Uhm. Ok, 4,7kO, or does two 10kO the job, too? I have only one 4,7kO.

[penfold42]

I used 4k7 resistors on each SDA and SCL.

Use your 4k7 for one of them and put 2x10k in parallel for the other

[penfold42]

I just noticed mine is doing this. I’m using the i2c on pins 3/5 and I have pull-up resistors.

If I slowly navigate with single keyboard presses it’s fine.
If I HOLD the down key to scroll continuously down, I see this issue

[penfold42]

And now mine isn’t doing this.

It’s an intermittent issue.

On reset, sometime the display is corrupt. If it is, I always get the extra line.
If it’s not corrupt at start, then it’s fine.

I notice the ssd1306 data sheet has a software init flow diagram for which registers need setting up and in what order - I’ll check this against the code.
Another possibility is the display needs some delays during init.

[thErZAgH]

Yup. Same here.
Some times at the startup it looks like TV has no tansmission (white noise).
Some time the text on the screen is garbled.

I don't know if this could help:
https://github.com/adafruit/Adafruit_SSD1306

[thErZAgH]

Could this be one of the init problems of the SSD1306?

This line

SendCommand(SSD1306_CMD_ENTIRE_DISPLAY_ON);

is not a the end of init routine in

[]https://github.com/pi1541/Pi1541/blob/master/src/SSD1306.cpp

Could this be a problem?

EDIT: Tihs. This is not the problem. But: If the C64 is off the display shows garbled text some time!? If the C64 is on, the rate of the garbled text is less... I don't know why this happens...

EDIT²: If the text is garbled (C64 == off) and I switch on C64, the text resets to non garbled text!?!?

Yes. I have the two 4k7 R between +5V and the two data lines now...

M Y S T E R Y

[penfold42]

It is a mystery - I’ve noticed the pi1541 splash screen always looks ok.

My guess is some of the other hardware init code could be causing spurious junk to be sent

[penfold42]

#38 includes a workaround for this.

I need to find time with the logic analyser but for now I reissue the oled init commands again after all the other init stuff has happened but before the browse list pops up

[penfold42]

i jus noticed this in IEC::BUS Initialise

// Clear all outputs to 0
write32(ARM_GPIO_GPCLR0, 0xFFFFFFFF);

I wonder if this is glitching the I2C bus...

[pi1541]

Perhaps, try calling RPI_I2CInit before any write32(ARM_GPIO_GPCLR0, 0xFFFFFFFF); is called.

[penfold42]

Tried that, also tried changing mask to fffff0

The problem I’ve now got is trying to reproduce it reliably - even removing my workaround re inits