A20_olinuxino_LIME rev. H gerber files

[pac]

Hi All,
I have opened the A20-OLinuXino-Lime_Rev_H file using EAGLE 9.1.0 free.
On the Left margin of the picture are indicated many errors.
Can anyone tell me what they refer to, and especially if the layout is final?
I guess the errors are related to the insulations, but I don't understand if the file is the final to generate gerbers,
Is there any parameter to change?
Thank you in advance,
Paolo

[LubOlimex]

The errors are normal and expected. These are mainly caused by the wire clearance around the main chip. We use Eagle 4.16r2 and there is a global PCB setting for the distance between wires and components. However, different parts of the board allow different clearance. For the rest of the board we have clearance of 5mil but we have lower clearance around the chip - usually 4.2mil. So there are errors around the chip. We can increase the global clearance distance and that would remove the errors around the main chip but this would make catching error around the rest of the wires harder.

The files that you get from GitHub are the files that we use to generate gerbers. The files are directly taken from our production so they are good.

[PaddleStroke]

Hi there,
I have another question about the A20 layout, as there's a topic open right there about it, I thought I would ask it here too.

Do you have an impedance control reference file for the olinuxino-Lime ?
Especially I was wondering if the SD card reader traces have impedance control?

Another question is about your 4.3" LCD module that I just got from the shop. I can't find how to modify brightness. I checked the schematic and it seems that the +28V chip do not have anything to control it so I guess the brightness can't be changed?
How would you add something to control the brightness? With a PWM maybe? Is there one specifically for this purpose?

Thanks for your awesome work!!

[LubOlimex]

Another question is about your 4.3" LCD module that I just got from the shop. I can't find how to modify brightness. I checked the schematic and it seems that the +28V chip do not have anything to control it so I guess the brightness can't be changed?
How would you add something to control the brightness? With a PWM maybe? Is there one specifically for this purpose?

Umm, LCD_BKL should serve this purpose. It is routed to LCD pin #36 which is connected to a PB2/PWM0. I am looking at this: https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/LCDs/LCD-OLinuXino-4.3TS/Hardware%20revision%20C/LCD-OLINUXINO-4.3''TS_Rev_C.pdf - and also check the LCD connector of the LIME board.

Do you have an impedance control reference file for the olinuxino-Lime ?
Especially I was wondering if the SD card reader traces have impedance control?

I looked but it seems we didn't keep it. Looking at the PCB for the mini SD card connector it seems like the data lines are made nearly equal in length and the clock is made longer.

I also have some wire lengths for RAM and eMMC, which are more interesting for us, hence we keep it.

[PaddleStroke]

Thanks for the feedback.

About impedance I heard it is calculated based on several things : trace lenght, trace width, spacing between traces and substract dielectric and thickness.

I found some data about USB, it seems that USB lines should be 90 ohms calculated on the different element above. In order to achieve correct impedance, pcb factories will vary the trace width in order to match required impedance.

But on SD card I can't find similar data yet