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Forum : Digole Serial Display : Color LCD Modules :

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Max. SPI speed for LCD?

I have succesfully connected my LCD with I2C and I could run all Arduino samples.

But now I jumpered the LCD for SPI and some features don't work correctly.

1. I can't draw 262k images ( eyes )

2. the flashing / negative text doesn't work (setMode(' ~' ) )

Is it, because the ESP8266 SPI setting is too fast?

RE:Max. SPI speed for LCD?

 Most possible: Yes, the receiving buffer in display could be overflowed if data speed too fast.

RE:Max. SPI speed for LCD?

How can I reduce SPI speed?

I don't use <SPI.h>, but only <DigoleSerial.h> and I don't see a way to reduce speed.

<SPI.h> has the option to set halfspeed, quarterspeed and so on, but not when i call <DigoleSerial.h>.


RE:Max. SPI speed for LCD?

I studied DigoleSerial.h and found these three lines in the SPI version of void read1()

        digitalWrite(_SSpin, LOW); //tell display module I will read data
        digitalWrite(_SSpin, LOW); //delay about 5us to wait module prepare data
        digitalWrite(_SSpin, LOW); 

Maybe this doesn't work on faster MCUs like the ESP8266 ( 80MHz )?


RE:Max. SPI speed for LCD?

After a bit more testing, I got the touchscreen_freehands_demo working over SPI and also the font_commandset_in_flash.

But the combination of flash and touchscreen only works over i2c ( checkbox and radiobuttons_demo )

You mentioned a pulldown resistor for the SI pin to make flash and touchscreen work in SPI mode,but there already is a 4.7k resistor on the SDO pin of the LCD.

Do we have to add a pulldown resistor to the data pin?


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