Uno and Mega 2560 comptatible ?

I had project working fine on my Arduino Uno Due to lack of SRAM I swapped in Mega 2560 with all connections same Result was a) my micro SD drive failed at init b) my GSM unit failed init ( fona.begin )

SD: Only idea I had was to reformat, even though card was working fine in my laptop

GSM: Tried change to HW serial (was using Software on Uno ) No change Not sure what serial FonaTest would use, I tried all 3 HW serials I have on 2560

General: Not sure if I have power enough .. ? With both external power and USB connected I had 4.70 V on my project board (feed from 2560 +5 V ) Only external power give me 4.47 V Little suprising for me was I had less power to project board when I feed from Vin ... My external power is for 2 A

Any other known problems for GSM and SD drive when going from Uno to Mega 2560 ?

All testing was done with the Example programs. Those working on the Uno (as well as my own programs)

Any idea on this would make me happy ;)

BR Bosse

4.47 volts is a bit low. Why do you think it is so low? Is it different on your other board (Uno)?

Found a 12 v 1A external Now i got 4.8 V on the +5 v regulated

Onboard regulator is only good for 800mA - after that you are pushing its regulation ability and output voltage may drop.

Thanks guys for input, turned out it was not a power problem

SD solution: Other pins for the 2560

SPI Uno Mega SS 10 53 MOSI 11 51 MISO 12 50 SCK 13 52

Using pins 50-53 solved problem

GSM solution: Not same pins that is usable for software serial

UNO 2560 2 10 RX 3 11 TX

Solved that problem :) Hope someone else can benefit

Ha det gött Bosse