First post and first Arduino/uC project.
I've designed and etched my own Arduino clone based on the single sided schematic to control an espresso machine (Via solid state relay).
[u]First question is around grounding.[/u]
I run a 12v cellphone charger as a power supply into the 7805 regulator. It just as 2 prongs into the wall so no "real" earth. The negative of the power supply is the ground of the board. Does this mean I have a floating ground. Is this ok?
Next up I have a Nokia CA-42 as a USB to TTL module which connects to laptop so now the Arduino board has a ground from 2 places the power supply and the USB ground of the laptop.
Can this cause any strange ground issues? I've already killed one CA-42 module not sure how.
I have had it up and running including the 1602 LCD and uploading code but at times I feel the uC is getting warm! (not hot but warm). I've had erratic results from the LCD and uC?, garbage on the screen, crashing etc And what appears to be contrast fading away after a while.
I'm running the LCD backlight (20ma LED) direct (via 47 ohm resistor) off the uC (Arduino digital 9). This should be ok right? I wanted to do this so I could fade with the PWM.
Any help including general comments on my design would be much appreciated. I WILL start over with a new board design if I have to but really don't want to! It goes with out saying that I should have done more prototyping on the bread board before I jumped into PCB design!
Kind Regards, Rhys