Looking to port u8g2 for PIC Microcontroller. Anybody been there already?

[ChiefEngrNY]

Greetings,

I am looking to port the u8g2 driver to run on a MicroChip 16-bit PIC MCU - something in the PIC24 Family. The PIC development environment compiles C code for the PIC so starting with C is great.

I'm looking to see if anyone has been down this path before - both porting u8g2 to a different MCU as well as trying to get it running on the PIC24. If so, I'd love to learn from your experiences.

If the price is right, I would be willing to fund the job of porting the package.

Thanks in advance for any assistance and experience anyone might have.

[olikraus]

Topic/discussion had been here: #70

So, one precondition is this: You need the professional version of the c-compiler.

If this is the case, you can just go ahead with the instructions from here: https://github.com/olikraus/u8g2/wiki/Porting-to-new-MCU-platform

[olikraus]

There are only wiki documents.

[devau]

Hello
I would like to port usg2 to a PIC16F1825 and then compile it with CCS compiler. @olikraus: The documentation on how to do this is vey complex! I agree with ChiefEngrNY saying "If the price is right, I would be willing to fund the job of porting the package."
I think there are lot of users, not only dealing with Arduino stuff as Microchip's PIC controller are widly used with OLED displays. What do you think about it?

[olikraus]

As mentioned, you would require the professional version of the compiler (well I do not know the current situation, but at least it was like this many years ago).

The documentation on how to do this is vey complex!

Well, could be, but actually, if you have a I2C display and you know how to clear and set a port, then the HAL code is very simple.

See the HAL code for ARM here: https://github.com/olikraus/u8g2/blob/master/sys/arm/stm32l031x6/u8x8_test/u8x8cb.c

Ok, still the code looks complicated, because the code does all the register updates, but it is really just a little bit of delay and GPIO clear/set functions.

The setup code itself is also simple:

u8g2/sys/arm/stm32l031x6/u8x8_test/main.c

Lines 358 to 363 in b1a4917

	u8x8_Setup(&u8x8, u8x8_d_ssd1306_128x64_noname, u8x8_cad_ssd13xx_i2c, u8x8_byte_sw_i2c, u8x8_gpio_and_delay_stm32l0);
	u8x8_InitDisplay(&u8x8);
	u8x8_ClearDisplay(&u8x8);
	u8x8_SetPowerSave(&u8x8, 0);
	u8x8_SetFont(&u8x8, u8x8_font_amstrad_cpc_extended_r);
	u8x8_DrawString(&u8x8, 0,0, "Hello World!");

Also the magic is done with this call:

u8x8_Setup(&u8x8, u8x8_d_ssd1306_128x64_noname, u8x8_cad_ssd13xx_i2c, u8x8_byte_sw_i2c, u8x8_gpio_and_delay_stm32l0);

However the only function, which needs to be provided by you is the last callback function: "u8x8_gpio_and_delay_stm32l0" (the one which is linked in the first link above)
All other functions like u8x8_d_ssd1306_128x64_noname, u8x8_cad_ssd13xx_i2c and u8x8_byte_sw_i2c are part of u8g2 / u8x8.

[devau]

For sending data over I2C the CCS compiler has the command "i2c_transfer_out([stream], address, wData, wCount)". stream is defined internal, address is the I2C-address of the SSD1306 128x32 display, wData is pointer to data and wCount is number of bytes. Does this mean I have to place this somehow into code "case U8X8_MSG_GPIO_I2C_DATA:" ? In fact I do not have to set/clear ports directly as this is done all by the library of the CCS-compiler, which addresses itself the internal hardware controlled I2C-module MSSP (see: [https://www.sprut.de/electronic/pic/grund/i2c.htm] part "MSSP-Modul im Master-Mode"). Thanks for your help and greetings from Switzerland :-)

[olikraus]

Obviously, you can and should use your internal i2c_transfer_out procedure. In order to do so, you additionally need to reimplement and provide u8x8_byte_sw_i2c: Details are here: https://github.com/olikraus/u8g2/wiki/Porting-to-new-MCU-platform#hardware-i2c-communication

The mentioned approach above is more like a first simplified step with as little extra effort from your end. Obviously I2C bit banging will be much slower than using i2c_transfer_out.

Greetings from South Germany ;-)