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Hi all. I am working on a project using a MEGA2560 clone and a 3.2 display board. I need to move up to a 4.3 display so I purchased the NHD-4.3RTP-SHIELD-V. The problem I am dealing with is when I install the display board, the computer will not recognize the USB connection and says it is malfunctioning. I tried it with and without external power and no difference. If I remove the display and plug in the MEGA by itself, everything is fine. I can upload the example. I can then replace the display, power up the unit and it seems to work fine. I have not seen this problem at all with the 3.2 display.

Has anyone else experienced a problem like this???

Hey Matt,

If it's not a genuine Arduino you can never be quite sure what you are getting. It sounds like the MEGA2560 clone in addition to the NHD-4.3RTP-SHIELD-V is drawing to much power. To prevent damaging your computer, the USB device drawing too much power has been disabled. Other devices may have also been disabled. When you disconnect the device drawing too much power, your other USB devices will be enabled again.

You can utilize a cheap USB Power Meter to monitor how much power is being drawn. If you notice to much power is being drawn between the two devices try dimming the backlight on NHD-4.3RTP-SHIELD-V to drop the current consumption.

The backlight control pin is a pulse width modulated (PWM) signal controlled by two registers: REG_PWM_HZ and REG_PWM_DUTY. REG_PWM_HZ specifies the PWM output frequency, the range is 250-10000 Hz. REG_PWM_DUTY specifies the duty cycle; the range is 0-128. A value of 0 means that the PWM is completely off and 128 means completely on.

Hope this help!

Hi Paul,
Thank you for a quick reply. Power draw was the first thing I thought of because of the larger display, so I put the assembly on a 7.5V @1A external supply and made sure it was running OK before plugging it in. The regulator got warm, so I think it was taking at least most if not all of the load, but I got the exact same error message.
The one thing you mentioned which might be the actual reason is the fact that it is a clone. It was pretty cheap, and made by someone I didn't recognize. I think at this point it might be a better use of time to order a genuine Arduino board, that way I will know what I have before spending a lot of time.
I will let you know how it works when the new board arrives. If anything else comes to mind, I'm all ears.
Thanks for your help!

Problem Solved!! Got my board in and plugged it in. Works like a champ!! It even uploads and works fine with only USB power.

Lesson learned - stick with the genuine article. You may not be saving anything with the cheaper ones.

Thanks for the help!!


Thanks for the update, enjoy the rest of your evening  :o


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