oled example code is not working

[ep.hobbyiest]

Hi,

I am referring to a code example from one old post:
https://www.ccsinfo.com/forum/viewtopic.php?t=52861

Which seems to be working for others. But when i tried it, then the controller got stuck at the Oled_init() function only.

I am using the PIC18F25K22 controller. Here is my main.h file:

[temtronic]

What voltages are you running the PIC and display at?
Most peripherals these days are 3 volt devices. PICs can be 5,3,2..so you need to read the datasheets and confirm basic information like this.
Also post the display make/model of the display or a link to it's datasheet.
Sometimes people use a 'module' and not the 'device', that info we need to know.
and
Since it's an I2C device, install and run the I2C Scanner program from the code library FIRST. It will confirm/deny the device actually IS connected( and what address) !

Jay

[Ttelmah]

If you look at this driver:

<https://www.ccsinfo.com/forum/viewtopic.php?t=54453>

You will see my comments about voltage.

The core chip is a 3.3v device. Though a lot of boards will run off 5v, the PIC at 5v will not see it's inputs go high (so will hang on an I2C write, when it sees the clock being held low).

Change your I2C setup to:

#use i2c(Master,Slow,I2C1,SMBUS)

Which will force the I2C hardware to use SMBUS switching levels, and may allow it to work.

With this change done, try the I2C scanner program and see if the device is found.

You will also find that different boards may need different configuration for the charge pump and similar settings, depending on how they are actually wired.

[ep.hobbyiest]

I am using 5 volt for the circuit as display also works on 5 volt

I am using following Display module SSD1306 i2c.

I tried i2c Scanner but nothing found on that.

But i have attached pull up of 1K8 and using Hardware i2c channel pins.

[ep.hobbyiest]

I tried following setting as well.
#use i2c(Master,Slow,I2C1,SMBUS)


But no effect.
Should i use software I2C on other pins?

I tried 3.3V power supply as well but for complete circuit.

[Ttelmah]

SSD1306, is the chip, not the module. Is there any data for the module you have?.
Have you tried the I2C bus scanner program?. Does it see the chip?.

[ep.hobbyiest]

I don't have any other data. I got it through ebay.
But yes we will get plenty of data online.

Yes i tried I2C scanner program which gave me result as Nothing Found.

[ep.hobbyiest]

It is working on different port than Hardware.
I tried C0 and C1 for SDA and SCL resp. And it it working.

But in my hardware i have used C3 and C4 pins. On that pins i2c is not working.

What could be the reason?

i checked connection again and again. Is that means pins are gone?

[Ttelmah]

No it's the voltage problem.

Software I2C on C3 & C4, will use TTL level input buffers. Will see anything above 2.0v as a '1'. Hardware I2C by default requires 3.5v to see a '1', which won't work with the 3.3v device. The SMBUS option should drop this to 2.1v, but it's either not working or it is still not quite low enough.
I was slightly dubious about the SMBUS option working, because it does change some other parts of the bus specification. Though 'nearly the same', it is not identical to I2C.
You could just use the original pins and select FORCE_SW.

[Ttelmah]

There is a way round, if you are prepared to use other pins.

Key is this note in the data sheet:

[ep.hobbyiest]

Okay.
i am using PIC 18f25k22 which has 2 hardware i2c built in on RB1/RB2 and C3/C4 pins. But pin mapping is not mentioned in the datasheet neither INLVL.

Yes. I have option to use software i2c on same pin (Which is not good choice).

[Ttelmah]

How are you doing the pull-ups?.
These should be to 3.3v, not 5v.
If these go to 5v, you risk reverse biasing pins on the SSD chip, and over-voltaging it. Also the chip probably won't meet the lower Vol specification for SMBUS if the resistors are pulled to 5v.

Why are you anti software I2C?. Except for the maximum speed there is no disadvantage to this. Since you are only running at 100K, this doesn't really matter at all.

However the CCS code may make some other slight changes for SMBUS, There are slight changes for this. So I'd suggest the best thing to try is:
1) Make sure pullups are to 3.3v.
2) Setup the hardware I2C as normal.
3) Then manually switch just the signalling levels to SMBUS:

[ep.hobbyiest]

Okay. Right now I don't have 3v3 regulator spare. But i will have to mention method because my pcb are on the way.

I am not against software i2c. I was thinking that if Chip has built in I2C then let's go for it.

[Ttelmah]

OK.

Try using this circuit for the pull-up:
(view with a fixed pitch font)