Porting SSD1306 for Oled

RE: Porting SSD1306 for Oled

Stian Røed Hafskjold — Thu, 30 Oct 2014 08:49:05 GMT

Please accept the answer if it worked. Create a completely new question if you have a new question. We want to have it this way so it is easier for other to find the answer to a specific problem if they have the same problem.

RE: Porting SSD1306 for Oled

Takatoshi Nao — Thu, 30 Oct 2014 02:33:48 GMT

I'm porting below code. but the font file is so large. bitbucket.org/.../ and I don't know how I can. T_T Please advice. After I success with I2C, I will try SPI. Thank you.

RE: Porting SSD1306 for Oled

Clem Taylor — Thu, 30 Oct 2014 02:22:41 GMT

Currently I'm using the SSD1306 in the vertical addressing mode, this seems to be the easiest mode to use, The hardware horizontal scrolling is farily useless. If you only have a 128x32 display you can do vertical scrolling by writing to the start line register. However the display I'm using for prototyping has a rather nasty bug: http://youtu.be/nIlNApuFGXo Writing the entire frame every frametime works just fine: http://youtu.be/KM-mhbYWSJ8

The SSD1306 4 wire SPI interface has a command/data pin, chip select, clock and MOSI pins. I do one command transaction to configure the address mode, then a data transaction to clock the entire 512 byte frame buffer (128x32x1bpp) and then an optional transaction to update the start line (to reduce potential tearing). Once I queue up the transactions all the data motion and setting the cs/dc lines is handled by the SPI interrupt handler.

RE: Porting SSD1306 for Oled

Takatoshi Nao — Thu, 30 Oct 2014 01:44:38 GMT

It worked. Can I ask another question?? how can I draw bitmap?

RE: Porting SSD1306 for Oled

Takatoshi Nao — Thu, 30 Oct 2014 01:43:41 GMT

Thank Clem.

RE: Porting SSD1306 for Oled

Clem Taylor — Wed, 29 Oct 2014 23:12:43 GMT

If your hardware isn't fixed yet, save yourself some pain and use the SSD1306 based display with SPI not I2C. The SPI interface is so much faster and requires much less CPU time to feed.

I'm using a SSD1306 based display with the SPI interface and I've been very happy with it (except for what seems to be a chip bug in the handling of writes to the start line register).

RE: Porting SSD1306 for Oled

Stian Røed Hafskjold — Wed, 29 Oct 2014 15:38:53 GMT

In this function:

return twi_master_transfer(SSD1306_SA << 1, data_buffer, 2, TWI_ISSUE_STOP);

you are shifting the address 1 bit left. In the SSD1306 documentation, the address should be in this form:

0 1 1 1 1 0 SA0 R/W

Which is 0x3C shifted one bit left. (As long as SA0 and R/W is 0)

You can set SSD1306_SA to be 0x3C, or write 0x78 directly like this, as Nenik suggests:

return twi_master_transfer(0x78, data_buffer, 2, TWI_ISSUE_STOP);

RE: Porting SSD1306 for Oled

Takatoshi Nao — Wed, 29 Oct 2014 11:52:39 GMT

hello nenik, SSD1306_SA is 0x78. but it's not worked. can you advice to me? Do I have to use 0x3C???!!

RE: Porting SSD1306 for Oled

Nenik — Wed, 29 Oct 2014 07:00:22 GMT

What is your SSD1306_SA? 0x3C? I use very similar code and SSD1306 based display and it works well for me, but I use 0x78 directly (the shift might have been already factored in the datasheet, IIRC)