New 2.2" color LCD option

[tddrummer]

Dmitri,
I have verified the wiring is correct. I will need to purchase another MD board from you.
It is the 56 input version with PS. I will only need the main board.
Thanks

[Jorns Bergenson]

I'm working on another project using these small TFT LCD displays and I've tested three models on MegaDrum. The LCD modules are all based on the ILI9340/ILI9341 controller and were purchased from eBay. I have tried 2.2", 2.4" and 2.8" display modules. There are a number of 3.2" displays that are available but the documentation I found says that they need 7.8V for the backlight LEDs - not really an option for MegaDrum Since only 5V and 3.3V supply rails are available.

Here is a 2.2" module. It includes a transistor (Q1) that allows the backlight to be controlled using a PWM.



Here is a 2.4" module. It is the largest LCD module that will fit in the enclosures I am using for MegaDrum (Box Enclosures B4-160).
It does not allow a PWM signal to control the backlight intensity directly. The "LED" pin connects to the anodes of the backlight LEDs so an external transistor is required. I found that connecting the "LED" pin to 5V through a 100-ohm current limiting resistor made the backlight comfortably bright. I measure 2.8V at the module's "LED" pin which is well under the 3.3V maximum that has been suggested for these displays.



Here is a 2.8" module. It also does not have a transistor for PWM backlight control. Everything I wrote about the 2.4" LCD's backlight applies to this one as well.

[tddrummer]

It is possible to get the 7.8V from the 5V if you use a boost power supply. Also, what 3.2" displays have you found? I have only seen displays that have a resolution of 480x600.
The ones that have the 240x320 have a different interface (pinout).
I am curious to hear what your opinions.
Thanks

[Jorns Bergenson]

It is possible to get the 7.8V from the 5V if you use a boost power supply. Also, what 3.2" displays have you found? I have only seen displays that have a resolution of 480x600. The ones that have the 240x320 have a different interface (pinout).

If you search eBay for "3.2 LCD ILI9341", you will get plenty of hits. These modules have different pinouts because they support parallel in addition to serial modes. To find out how to get the controller into serial mode, download the ILI9341 datasheet. If the LCD module actually requires a 7.8V power supply, I think you be better off using a higher voltage external power supply (9V or 12V) and then deriving the 5V and 7.8V for MegaDrum and the LCD module.

Personally, I don't think it worth the trouble - these modules have limited documentation so it might be very difficult to get them to work without much benefit over the tested modules.

Just my opinion.

[tddrummer]

Hi all,
Who has used a 2.8" TFT LCD? I am having issues with mine.
There is no SDA pin on the LCD. There is a MOSI (SDI) and a MISO (SDO)
I have wired the SDA pin from the MD board to the MOSI pin. I am getting a flicking withe screen with 4 color bars.
Is the display resolution compatible (320x240)?
If anyone has used one, could you post a picture of the wiring?
Thanks

[ignotus]

If you look at page 3 of this thread I describe how I got mine working. You just have to follow the same pin order as for the ST7735 screen shown in the manual, except for the LED pin, which goes to pin 15 instead of pin 3 on the header. You also have to bridge pins 11 and 12 instead of 13 and 14.

[Jorns Bergenson]

Hi all,
Who has used a 2.8" TFT LCD? I am having issues with mine.
There is no SDA pin on the LCD. There is a MOSI (SDI) and a MISO (SDO)
I have wired the SDA pin from the MD board to the MOSI pin. I am getting a flicking withe screen with 4 color bars.
Is the display resolution compatible (320x240)?
If anyone has used one, could you post a picture of the wiring?
Thanks

First, the assumption is that you are using a module based on the ILI9340/ILI9341 LCD controller. The SDA signal should be connected to MOSI. The MISO pin on the LCD module should be left unconnected.

Could you list the names of the pins on the LCD module's connector, or better yet provide a picture of it?

Here's how I wired up the LCD modules that I am using on my MegaDrum units. The "LED" pin can also be connected to pin 15 of the LCD connector, but I found that the backlight was a little too dim for me. Using the 100-ohm resistor between 5V power and the LED pin made the backlight just right for my situation. If you have the latest MD firmware, you can use a jumper between pins 11 and 12 instead of a 200-ohm resistor.

[tddrummer]

Hi all,
My wiring was correct, it was the jumper. I misinterpreted the post earlier in the discussion.
The manual will need to be updated. I will probably try an inline resistor for the backlight,
but the display looks pretty good as is.
Thanks all for the help.

[Perfn]

If you look at page 3 of this thread I describe how I got mine working. You just have to follow the same pin order as for the ST7735 screen shown in the manual, except for the LED pin, which goes to pin 15 instead of pin 3 on the header. You also have to bridge pins 11 and 12 instead of 13 and 14.

Hello,

I was thinking of buying the same LCD from Ebay and use it. But I'm certainly no genius when it comes to this and need some help.
Could you explain how the pinning is done more thoroughly? Because I'm looking at the instruction manual and comparing the pining on the connector, old lcd and the one on ebay and i don't understad at all. I mean, where did all the db pins go for example?

[ignotus]

If you're getting the exact same LCD as I got, I can't really explain it any clearer than what's posted 3 posts above. I don't mean to sound harsh, but if you can't understand that diagram it might not be a good idea to try it.

PS: what's a db pin?