3Wire SPI Help CFAL25664C0-021M-W

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black.wayne@blackboxembed

New member
I cannot seem to get this dsiplay to work in 3 wire SPI mode. I am using the CFA-10102 breakout board with all the recommended connections to connect to a cypress CYBLE-416045-02 mcu. Using the supplied arduino test code modified for 9bit spi transfers, I think I'm doing things correctly, but can't get anything to display on the screen. Fyi, I have scoped the clk and mosi signals and integrity is good. HV is 12V and LV is 3.2V. Ive tried all 4 spi modes w no difference. Here are some screen shots of my essential spi 3wire pins states and the transfers.

20230703_171844.jpg
init_9bit.png
Data_9bit.png

Any Ideas?
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CF Kelsey

Administrator
Staff member
It looks like you have the reset pin (pin 18) tied high. Try controlling the reset pin as shown in the demo code. During the display initialization, the reset pin should be toggled low and then pulled high to ensure the starting condition of the controller chip.
 
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black.wayne@blackboxembed

New member
If that is the case then this OLED is a nonstarter for our product. I need a non-I2C 4wire interface (+,-,dat,clk) to replace a dotstar matrix. Is there Any OLED that is true 3Wire (+,-,dat,clk) SPI?
 
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CF Kelsey

Administrator
Staff member
You could mimic the reset pin by connecting a resistor and capacitor between the reset pin and VCC to pull the pin low briefly on power up.

I would suggest trying the reset toggle now, just to determine if that is the issue or if there is something else wrong
 
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black.wayne@blackboxembed

New member
Yes that may be an option. What king of RC tc would you recommend? Currently I have tested toggling the RES line per the seeduino code which is a set/clr/set sequence. Ive been doing that w gpio with a 5ms activle low pulse and I am able to reset/init the display. Im currently running into an issue with the 9bit spi transfers. The PSOC TX fifo is limited to 64 bytes using 9bit so Im sorting out a way to perform full 128 byte page writes to updated the display ram.

Thanks for the RC tip, good idea...
 
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