Multiple oled displays on spi without cs pin?

Other Hardware Displays
1

Hello,
i bought 4 oled displays but they came without the cs pin. I wanted to use al 4 on the same arduino over spi, is this possible without the cs pin?
Pins on the display GND, VCC, SCL, SDA, RES and DC

Here is a picture of the display

3264×1836 1.27 MB

Hope someone can help me out

that is my code, but its not working i get strange things like display 1 shows nothing, and display 2 shows "display 2" but flickering or something erlse.
If i comment one of the picture loops it seems to work but, i cant use both displays at the same time

#include <U8glib.h>

#include "U8glib.h"
U8GLIB_SSD1306_128X64 FR(13, 11, 10, 2, 8);
U8GLIB_SSD1306_128X64 FL(13, 11, 10, 3, 8);

void draw(void) {
FR.setFont(u8g_font_unifont);
FR.drawStr( 0, 22, "Display 1");
}

void draw2(void){
FL.setFont(u8g_font_unifont);
FL.drawStr( 0, 22, "Display 2");
}

void loop(void) {
// picture loop
FR.firstPage();
do {
draw();
} while( FR.nextPage() );

FL.firstPage();
do {
draw2();
} while( FL.nextPage() );
delay(50);
}

Regards

2

Hi

Maybe it work if you use another full set of pins for the second OLED.

Oliver

3

I really can't believe that anyone would make an SPI device without a CS pin.

Your module does have a RST pin and it does have a D/C pin on the male header.

I would see if you could route the chip /CS pin to replace one of those.

I am not at a PC. Most controllers have a 9-bit serial mode that avoid the D/C pin.
Some controllers have a Software Reset command. So you could avoid the RST pin.

I would prefer the RST replacement because the AVR can do 8-bit SPI in hardware.

I suspect that Oliver has some better ideas.

David.

Edit. After a swift glance at the data sheet. There is no Software Reset command. 3-wire is selected with BS0=1.
The 3-wire 9-bit SPI mode says that D/C should be tied low, CSn synchronises the transmission.
It may be worth trying the D/C pin as a "chip-select".

The thought of a SPI device without a hardware chip-select is frightening. The SSD1306 has a NOP command (0xE3). I do not see how that would be able to re-synchronise after a glitch on the SCK.

This display looks a better choice http://www.ebay.com/itm/0-96inch-OLED-Display-Module-A-128-64-SSD1306-SPI-I2C-with-horizontal-pinhead-/251610028827?hash=item3a95205b1b:g:ft0AAOSwxCxT4e84

4

I fully agree with David. To myself it was almost unthinkable that a SPI device could exist without chip select. But they are actually sold.

According to this thread, there might be a solder pad, which could be used, once the 0 ohm resistor is removed:

oled-1.jpg
oled-1.jpg640×541 75.1 KB

(Picture from Caltoa)

Oliver

5

Hi I was just wondering if you managed to get multiple screens working independently over spi I'm looking to run 4-5 small colour screens independently. Coming from a software background I'm not sure of the right hardware selection and wiring it all up.. Would you be able to give me some pointers??