ST7735S

[MagTer]

Hi,

I just received a display module with a ST7735S that I am trying to light up with the ST77xx module.
Since I am having issues getting anything on the display I started looking for problems.

One thing I found was that the chip was a ST7735S instead of a ST7735 that is mentioned in the documentation.
Could that be the issue?

I'm am so far just connecting VCC, GND, MOSI --> "SDI", CLK --> "SCL" and nothing happens except that that backlight turns on.

[Ath]

Aren't there CS (chip select) or Enable and DC (data/command) pins available on the display? That's used to enable the display and for receiving data or commands. There may be some units that don't have the CS pin available, but DC should always be connected to the ESP for it to work as intended. The RES/RST (reset) pin is optional.

[MagTer]

Thanks for your response Ath.

I tried that, as well. Right now, I have all cables connected between the Lolin S3 Mini and the ST7735S.

I have tried moving the SPI interface(MOSI,MISO,CLK) to custom GPIO ports, changing the optional pins to new GPIOs. Still nothing.

Connections from S3 mini --> ST7735S

CLK: GPIO-36 --> SCL
MISO: GPIO-37 --> SDO
MOSI: GPIO-35 --> SDI
CS: GPIO-14 --> CS
DC: GPIO-38 --> DC
Bckl: GPIO-40 --> BLK

If I put an update interval on the device, I see that the screen flickers every three seconds but other than that only the backlight config works.
Seems like I must be missing something very basic, or both the displays are broken/not compatible.

Amazon link for the displays: https://www.amazon.se/dp/B0B1Y3GBJ6?psc ... ct_details

[Ath]

Have you tried swapping the MISO and MOSI pins? Most devices interpret the In/Out from their own perspective...

[MagTer]

Yep, I have tried that too.

I found an arduino example for using SPI towards a display that used resistors for bringing down the voltage as it defaults to 5V and the displays need 3.3V.
Not only for the VCC but also for the SPI connections. Is that something that is needed with the ESP's as well?

In that case, I might have fried my display and that is then the reason for it not working

I am using 3,3V for VCC but the others are just straight connections from the S3 to the display.


Ref: https://www.youtube.com/watch?v=4DtuOeeYHys&t=577s

[TD-er]

The "old" Arduino platform is 5V.
Meaning the logic levels are also at 5V when "high".
ESP processors run at 3.3V and thus should be compatible with your display.

Just make sure to connect the 3V3 pin to power the display if it only accepts this voltage and not the V_in pin of the ESP board as that's 5V.

[Ath]

I assume you have checked the actual wiring at least 3 times? I've seen too many cases where just the wiring was faulty (mostly local) causing stuff not to work as expected...

[Ath]

Hmm, I see you have used GPIOs 35-37 for SPI use, but according to this Espressif ESP32-S3 documentation, these pins should better be avoided. Can you use other SPI GPIO pins instead? (they are to be configured at the Hardware tab, but you probably found that already).