Multiple Oled SPI Displays

(deleted)

Those OLED's don't have a standard SPI interface. There is no Slave Select. So, no, you can't do it.

The chip supports CS/. Do they not break it out to the headers for the user?
See page 17, 18. Looks like standard SPI.

I have used them. There is no chip select. If you have a different experience, please post it.

Please post a link to the actual display(s) that you have bought. e.g. Ebay sale page

MK1888:
Those OLED's don't have a standard SPI interface. There is no Slave Select. So, no, you can't do it.

I have never seen a SSD1306 SPI display without a CS pin.
If we knew which display you have, we could make accurate comments.

Four SSD1306 displays should work fine on the SPI bus. However you need to be careful with libraries.

Adafruit_SSD1306 uses 1024 bytes of SRAM for each display buffer. i.e. 4kB
U8g2lib can work with small buffers.
Text only libraries can work without any buffers.

David.

david_prentice:
I have never seen a SSD1306 SPI display without a CS pin.

I have never seen an SSD1306 SPI display with a CS pin. They have D/C, RST, SDA, and SCL. Six pins in total. No CS. Please post an image or link.

...I just did an image search. It might be that the displays that are half yellow half blue have the CS pin. I have only used the solid color ones. No CS pin. And neither RST, nor D/C can be used as CS.

Oops. I have not bought an SPI OLED recently. Now that you mention it, there are some with 6-pins.

I have always bought 7-pin displays. i.e. with CS

It is a mystery why anyone would make or sell a 6-pin board. Life is very difficult without a CS pin. The SSD1306 chip behaves impeccably with CS.

However the old ST7920 chip (LCD) does not behave in SPI mode.

David.

MK1888, aren't you describing an I2C bus? What kind of Bus does this guy have?

-jim lee

(deleted)

Try it and find out? A true SPI has a different interface: MOSI, MISO, SCK, and SS/CS. The library you use, of course, matters. If you're displaying graphics you need a buffer for each screen. That's a LOT of RAM. If just text, no buffer is needed. I have done buffer-less test-only code for Microchip PIC, I don't know what's available for Arduino.