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Custom board with CharDisplay module or a TE35


#1

I plan to build a custom board based on G400D and 3 samtec 1.27 connector.
I would like to have the choice to connect a CharDisplay Module or a TE35 according to the application.

I plan to put 3 Samtec connector for RGB. Those are refered as Y on the G400 breadboard. My question is how to connect the CharDiplay module? Documentation says it needs a Y socket. May I connect it to R, or G or B without taking care? how the code knows on wich connector it is connected when I am using plain netmf?


#2

For char display you need a connector that has 7 GPIO’s.
4x data
1x Backlight
1x R
1x E
All are used as digital outputs.
So if all 7 non power pins of the R G or B connector are GPIO’s, then you’re fine.
None of them needs to have any special capabilities.


#3

Thanks Reinhard

I need also other informations regarding TE35 and T43 wiring.

On the G400-D module specifications, LCD dedicated pins are associated with green colors. However on G400HDR PA28 is connected to pin 9 of socket G. Unfortunately, I reserved PA28 for an other purpose and all IOs are already used. Pin 9 of socket G is supposed to control backlight or SHDN.

I suggest GHI team to recheck the documentation, Pin 9 is refered as SHDN while it’s SHDN# in the schematic. Without this info I would have pulldown this pin whereas it has to be pull up… Pin 139 of G400D should also be refered as LCD backlight or LCD SHDN in the brochure of G400.


#4

Gadgeteer specifications do indicate that Pin 9 on G socket is to control the backlight of an LCD screen. Why do you say “backlight or SHDN”?

To which documentation and schematic are you referring that pin 9 is refered as SHDN while it’s SHDN# in the schematic?

As for the brochure referring Pin 139 [which i think you mean Pin 138 PA28], this would single out this pin as a special purpose pin which would not be accurate. The backlight pin for an LCD screen can be any GPIO pin. In the case of the G400HDR, PA28 was chosen. However, if you look at the FEZ Raptor schematics, PC21 was chosen, which also has PWM_3 as a secondary function, which will allow the backlight to be dimmed.


#5

This is described here:
https://www.ghielectronics.com/catalog/product/387

Here:https://www.ghielectronics.com/catalog/product/421
versus here: http://www.ghielectronics.com/downloads/schematic/Display_T43_Module_SCH.pdf

[quote=“Aron”]

[quote=“leforban”]
As for the brochure referring Pin 139 [which i think you mean Pin 138 PA28],
[/quote][/quote]
Yep You’re right…:-[

OK so LCD pins on G400 are reserved (they can be GPIO) but if I instantiate an LCD all of them will be reserved for this purpose. Then I can control the backlight or use touch surface using other IO…

The only thing I need to know is the voltage level needed on pin 9 of socket G to switch ON the screen


#6

@ leforban - In order to drive the backlight on the T43 and TE35, a signal of high is required. Measuring the voltage of the Spider’s output of Pin 9 on socket 13 (Type G) indicates ~3.2V. A signal of low will shut off the backlight.

As for the schematic SHDN and SHDN#, that is regarding the driver chip that is powering the LCD backlight. The driver chip has a shutdown pin (which is connected to pin 9) and setting that pin to low will turn off the LCD.

The labels on the socket listings are both technically correct depending on which way you look at them, however they are inconsistent. The T43’s description is indicating the driver function on the module while the TE35 is indicating the NetMF function from mainboard.

We will correct the T43’s pin description to reference the NetMF function. Thank you for helping us find this error. We always wish to provide the most consistent and correct information.