TFT long cable issue

Hi,

I am having weird issue with running TFT display over 1,5 meter cable with esp32, as once a few days display hangs and can't refresh display content. The cable I am using are wires taken out from UTP cat 5, not twisted.
When display hangs, esp controller is operating normally and I still can connect to it through wireless network.

Can you please confirm my doubts that it is related to wire thickness and I should use more solid cables? Or maybe need to add some resistors between TFT and ESP?
I was testing the display on short cables and didn't have any issue.

Hardware:

  • TFT 2.8" SPI
  • esp32-wroom-32u devkit

Attaching picture and connection diagram.

Thanks for any suggestions

Hi ...

I dont know its suitable for you or not ! but its better to have a another
MCU boards and ESP32 (i.e: UNO with ESP) for your SPI LCD,
then remove the wires and using wireless communication ...
(also parallel LCDs is faster than SPI LCDs, but needs 8/16 line for data transfer)

another test, use twisted pair cable with Shield (STP cable) instead of separated wires

SPI is not intended to go through wires. Your answer might be the Analog Devices LTC4332 SPI Extender it designed for operation in high noise industrial environments over long distances. The LTC4332 can transmit SPI data, including an interrupt signal, using a ±60V fault protected differential transceiver up to 2MHz over two twisted-pair cables.
The extended common-mode range and high common-mode rejection on the differential link provide tolerance to large ground differences between nodes. Additionally, the LTC4332 SPI Extender also supports external galvanic isolation on the link. The device offers a control interface using a separate slave select for configuration and fault monitoring.

SPI is not designed for long distant communication. It uses synchronous signal_._ 1.5M cable is antenna for EMI.

Thanks for reply and very useful comments. I am wondering however, why display is working for a few days and then it hangs. I would expect it not working at all.
On the other hand, when designing prototype I used this reference that says:

"The SPI interface is made up of three lines: SDI, SDO, and SCK. While the SPI communication method is generally suitable for distances up to approximately 10 m, to bridge longer distances, a repeater is often needed because of attenuation due to the increased line resistance of long cables"

https://www.analog.com/en/technical-articles/isolated-spi-communication-made-easy.html

moonspell79:
Thanks for reply and very useful comments. I am wondering however, why display is working for a few days and then it hangs. I would expect it not working at all.

Run your circuit with a high-amp Power Supply ...
(this need some testing for find problem :slight_smile: )

@gilshultz
LTC4332 SPI Extender is a good idea ...

@marteen1337, I am running on "big brick" high-amp power supply (104W, 15A). I used smaller PS at the beginning and that was also my first though, to verify if I deliver enough power and switched to "big brick".

My next plan is to use thicker cables and cut the distance to 120cm, as this is max what I need. Will let you know if that solved problem.

This topic was automatically closed after 120 days. New replies are no longer allowed.