My Due is outputting 4.3V! What's happened?

Official Hardware Mega Due
1

Hello guys,

I'm in trouble.

Measuring the 3.3V pin and the 5V pin from my Arduino Due and it outputs the same 4.3V both!

I put a PWM duty cycle to full on pins 9 and 10 and it outputs 4.3V!!

I am doing something stupid or what?

I am driving a bunch of things like a 7" Touch, a RTC DS3231, a Temperature sensor DS18B20, a few Relays, and am going to control a driver for High power LEDs with PWM. That's when I found out the issue, because I need to step-up the PWM from 0-3,3V to 0-5V.

Thanks in advance for the attention.

2

Did you connect the ground of your multimeter to the Due's ground or some other ground?

Do you have anything that could be putting 5V back onto the 3.3V pin? That can easily pull up the 3.3V to a higher voltage.

3

The ground is the Due's groung.

I have disconnected everything and it went back to normal. It seems that the LCD Shield is the villain.

I just wonder how this issue has not completely destroyed everything. I didn't even noticed, everything worked well until I checked. I've even changed the batteries of my multimeter.

4

http://forum.arduino.cc/index.php?topic=276821.0

There are jumpers shorted for both 3.3V and 5V VCC on the LCD Shield. WHY???

I just unsoldered the J1 and J3 like the guys on that topic above and now its everything fine.

Thanks for the help.

Note: Never, never, never buy Sainsmart stuff again.

5

RaphaelAmin:
Due with CTE TFT LCD/SD Shield and SainSmart TFT 3.2" not working - Arduino Due - Arduino Forum

There are jumpers shorted for both 3.3V and 5V VCC on the LCD Shield. WHY???

I just unsoldered the J1 and J3 like the guys on that topic above and now its everything fine.

Thanks for the help.

Note: Never, never, never buy Sainsmart stuff again.

Sooooo.... It's Sainsmarts fault you didn't take the time to properly configure the LCD before connecting it to the Due??

6

The LCD was OK (at least on the topic's particular issue). The problem was on the Shield.

I got no information that I needed to unjump anything as there is no datasheet to the Shield.

By the way, Henning Karlsen doesn't even support Sainsmart for his libraries because he knows they make garbage. The Touch doesn't work on the side of the screen. I had to do a anti-bounce code to work around a touch issue. There is no easy way to use separate power supply for the LCD since it drinks a lot of juice. I've got no support from them on anything. And now this: Jumpers shorted for both possibilites 5V and 3V3 without any advice that it should be unshorted.

So yes, sainsmart no more.