I recently purchased an LCD shield off of eBay where the seller forgot to tell me it worked with the Mega1280 and not the Mega2560. I of course have a Mega2560. I've spent some time reading about both and for the life of me I cannot figure out why it won't work?
All the Arduino literature I have found has said they are the same basically with the main difference in the chips being the amount of flash memory.
The only thing I heard anyone speak of about difference between both the 2560/1280 is that timing registers were not set the same way. I am not specifically sure what the timing registers would be used for since this shield uses the analog pins as digital outputs and not as analog inputs. But, I can think of no other reason why it wouldn't work.
Anyone have any ideas as to what could be different between the two that isn't apparent?
If you are curious which shield I am talking about, search for 2.6" TFT Arduino on eBay, it's 18.99 BIN.
grimepoch:
I recently purchased an LCD shield off of eBay where the seller forgot to tell me it worked with the Mega1280 and not the Mega2560. I of course have a Mega2560. I've spent some time reading about both and for the life of me I cannot figure out why it won't work?
If you are curious which shield I am talking about, search for 2.6" TFT Arduino on eBay, it's 18.99 BIN.
Being a bit more specific about the shield, like quoting an eBay number, would be helpful. The only 2.6" TFT I can see is sitting on a Uno. I am considering getting one of these for my Mega2560. The accompanying blurb discriminates between Unos and Megas, but not between Megas. When I moved from Uno to Mega, I understood there was no operational difference between a 256 and a 128, indeed it was recommended that I grab a couple of 128s while I can.
I have no idea about the half-speed operation on Megas. I don't think it is relevant.
Maybe the confusion is with a Uno sketch. The sketches work the same way but the pin calls are different, and I immediately had grief with my LCD shield. This was actually self-inflicted because I had a jumper to A2, but I see your shield is using the analogue pins. If your sketch is calling those pins for Uno, e.g pins 14 to 17, try adding 40 to those numbers.
I have an Uno R3 running 1.0.2, and have wasted 10-20 hours trying to get it to work. I can't. The ebay reseller tells me it works under 0023 and 1.0. So, I try it....No Bueno!
The reseller changed his description after I complained, now saying it only works on the Mega.
So because it will cost me more to send the fershlugginer thing back to China, and before reading this post, I buy a Mega 2560.
It doesn't work either. I suspect that the shield pins are off.