This little LCD Controller is the first I ever purchased back in 2011 and I’ve bought a few more over the years for various projects, suffice to say that it’s been my workhorse.
It features a common Realtek 8051 CPU (RTD2120L) and a less common scaler, the RTD2525 (or RTD2545 for the higher resolution R.RM5451).
It also comes in a variant with no DVI input (R.RM3xxxx) as well as a TV variant (R.RM6xxxx) which I’ve never touched.
The majority of Realtek based LCD monitors ever made had the RTD2120S CPU coupled with the RTD2553V or similar scaler, so the R.RMxxxx family are a bit unusual, but from a hardware perspective, there’s not much between them, it just runs different firmware.
Anyway, back to the subject at hand… In terms of its firmware, its OSD looks and feels a little more budget than what you’d normally find on a big name LCD Monitor, but it’s still the best available for hobbyists in my opinion. I don’t know for absolute certain, but from my poking around in the code running on these boards, it appears to be the handy work of this company.
The board comes in four versions, aside from the obvious variations (Audio and no audio) and here’s a breakdown of the less obvious differences:
|Max pixel clock
Max pixel clock
This effectively limits the refresh rate and resolution. Sellers often state this as “Max resolution” but this is the isn’t the right way to look at it.
Let’s take a common panel (LP141WP4) with a native resolution of 1440×900, and we’re using a refresh reate of 60Hz. It’s specified to have a blanking periods of 160 pixels horizontally and 26 pixels vertically, so we end up with 1600×926 pixels that have to be transmitted for each frame, which is 1,481,600 pixels
Now just multiply that by the refresh rate:
1,481,600 * 60(Hz) = 88,896,000 (88.8MHz)
So by that calculation, LP171WP4 would be slightly over the limit of what the R.RMx251 boards could handle, by my observations they can handle a little over, but I wouldn’t bank on it.
If we went to 70Hz on that same panel, now we end up with:
1,481,600 * 70(Hz)= 103,712,000 (103MHz)
At this point it would fall over, and the higher rated board would be required.
Most of this relates to the VGA input as the ratings are for the Analogue to Digital converter. With DVI input, higher pixels clocks are easier attained for both boards.
The boards with the higher rated pixel clock have switching regulators to support larger panels. +5V is switching on both boards.
I was told by NJYTouch that AT070TNA2-V1 wasn’t supported by this board, which officially may be true, but, eh, I’ve written a program to edit its firmware, so I can use it with any panel I please 😉
Conclusion: Having done quite a few LCD projects with different boards, this is the one to go for. It’s a good package for serious users (who buy the programmer), It’s fully supported by my ROVATools suite, and for those buying the pre-programmed board, it’s got about the best chance of working as expected 😉