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Hello Folks,
I have a second problem which i think needs a seperate thread.
I got a SSD1306 OLED Display running connected to a PSOC 4.
Now i wanted to connect two. Yes I know the SPI Bus is able to control more than one Device. but the displays i have dont have a chip select input -.- its really sad. so i thought its running via SPIM_UDB so i would hook MOSI and SCK to two de multiplexer and then switch between them with a control register. The D/C and RESET pins i control already seperate.
NOPE not working. I got a dissortet Transmission and also missing bytes while Data transmit to the RAM. Then i thought i could use a analog switch but the editor dislikes my idea.
Are there any possibilities to do that ? Maybe that my port choosing is not quite effective for the demux.
Ah, if i rewire the ports in the TopDesign each Display works seperately . ( if i hookup each set of pins directly to the UDB component).
here the connection chart:
SCK_1 = 1.5
MOSI_1=1.4
RST_1= 1.3
D/C_1 = 1.2
SCK_2 = 0.1
MOSI_2=0.0
RST_2= 4.3
D/C_2 = 4.2
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The SSD1306 data sheet says that even in 3-wire-SPI mode /CS is used as chip-select. So this should work as expected.
If you module really has only the SCLK and SDIN pins: use an OR gate in each of the SCLK lines to your displays. Only the display where the second input to the OR is 0 gets a clock, for the other one it stays 1 all the time. The OR allows you to use digital signals all the time, I guess the analog mux might not be fast enough for your purposes.
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The thing with the OR gates does the trick.
Two OR for the two Wires ( SCL and MOSI ) for each Display
And then one NOT and a 1 BIT wide CONTROL REGISTER. Nice thing.
Works really well.
Ill post later some schematics and screenshots.
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