Cable length limitations for RGB sockets

Can anyone comment on the maximum distance that reliable signal quality could be maintained when connecting any of the GHI LCDs using the RGB Gadgeteer sockets? My challenge is to use a TE35 display on the handlebars of an e-bike with the MCU mounted down near the bottom bracket of the bike (approximately 4 feet in total cable length and likely using 18ga multi-conductor wire for hookup).

I actually don’t know if you can easily get an answer for this, but my take is that this would be too far. You could however custom make cables that would work, with extra GND wires protecting the other cables and shielding as a whole.

I have a feeling that it will not be reliable. The DOT clock is sensitive to noise and the current socket configuration has no GND protection on either side of the clock line.

The other issue if you plan to use touch is that the touch lines will be very noisy with this.

Your only real way to do this is to convert the RGB levels to LVDS at the CPU end and then back again at the LCD but this will require a custom PCB to do this. You can then run several feet between them. I use the DS90C385AMT for the transmitter and DS90CF386MTD at the LCD end. If you use touch, you’ll need to consider an I2C long line driver for this and a suitable I2C touch interface driver. All of that will be able to run on a 20 core cable. I use FPC with that design.

There is also a few SERDES devices that will allow you to put the 16 bit RGB over a CAT5 cable. 1 pair for data, 1 for clock and 1 pair for power. DS92LV16TVHG is one such option.

Either way, I think you are going to have a bit of work getting it reliable without any additional hardware.

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I would say limit it to a meter; that’s 3 feet.

Edit: Wow, I just realized how unscientific that comment of mine was.

I have a doubt it will even go that far. The TE35 clock is slower than the bigger LCD’s but it still 16MHz. With no GND on both sides this is pushing it. I have an issue with a 30Mhz LCD going even 100mm on ribbon cable because the designer didn’t include any GND protection. You need a clean clock edge to ensure good LCD timing.

If they have the resources and the parts, they could try but I have a feeling it will fail for sure at the required 4 feet, and even at a quarter of this.

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What if I instead used an SPI LCD? I do not need fast refresh rates so the inherent lagginess is not a problem. A Google search shows a few references to SPI being reliable up to 10ft. Anyone have experience with this? Any cable concerns?

@ dekes1 - What NETMF hardware and what SPI Display.

I have tested the G120 and Newhaven NHD-0220D3Z-NSW-BBW-V3 which works.

What about these? I’ve heard they are pretty good and serial so your 5ft will be a doddle.


Dave thumbs up my friend
I have a number of generic spi touch displays, but learning about those Nextion dislays has me excited. With their onboard GPU they can manage UI rendering internally. And there’s already a library here on codeshare. Time to order a few of those to experiment with

@ dekes1: Nextion is very interesting solution with some limitations you have to aware. The most important one I know is rendering dynamic images.
Otherwise it is very easy to use.
Driver on codeshare is very old so I suggest you to take one from here: