If you have been following the TTL board posts you probably have read most of this already.
I am proposing to test the Mega2560 board (here after called Mega) using an L7 Eleks Maker board as a "Sheild". I will use bread board wires to make connections from the headers on the Mega to the the headers on the L7 board. The Arduino Nano board will be removed from the L7 board. This means that the stock cabling in our Laser kits will be able to be used without modification. The Stock Laser will operate just as it does with a Stock L7 board. I hope!https://www.adafruit.com/products/153
As an aside the L1, L2, L7, L8 or L6 boards should all work exactly the same. https://www.arduino.cc/en/Products/Compare
This is not a "permanent" solution. This is a test as to the performance of the Mega versus the Nano controllers. Hopefullly I can come up with a "sheild" that uses the advanced features available on the Mega as an upgrade for our machines. This would mean drawing up a board designed for these laser kits.
The real goal would be to get a ARM powered solution that will really improve performance over these Arduino boards. Grbl is headed that way but not there yet. The Mega would be an intermediate step to better performance and the firmware is available now. It is in BETA but has been out for about 5 months and is based on grbl edge, the precursor to grbl 1.0, the end step of the Nano/Uno work. Grbl 1.0 is supposed to be out "soon" and supposed to support a Laser mode that will enhance laser performance. these updates will also be applied to the Mega branch.
As you can see from this comparison chart both have the same clock speed of 16Mhz. The Nano, with 328P, has 1KB EEPROM, 2KB SRAM and 32KB Flash storage. The Mega has 4KB EEPROM, 8KB SRAM and 256KB Flash storage. There is a lot more resources available on the Mega. Many will see the 16Mhz and think you will not see any speed advantage from the Mega. This is not the case, grbl firmware allocates twice the the Block Buffers on the Mega and 40% more Segment buffers. This means that the Mega accepts more code into memory at each read. So less time is spent reading and writing to memeory. So less of a load on the processor for the same amount of code. This "comparison" will not compare the added "pins" that are available to be used by the Mega. We will use exactly the same number of pins as the L7 board uses, though they may not be the exact same pins!
In my earlier ramblimgs I had thought that re-doing the cpu_map for the Mega firmware;https://github.com/gnea/grbl-Mega/
was the way to go. meaning re-allocating the mega pins the same as the Nano pins used. This would have worked. I now believe for simplicities sake the better route is to use the default mega pin mapping to run the tests. This means people will not have to fool with cpu_map at all. And if we find a solution to using the Mega in our machines people will not have to remember what they changed. I would like everyones thoughts on this!
I plan on posting plenty of pictures of this Frankensteins mess in case any of you wish to follow along.
@Zax pointed out to me that T2Laser does not necessarily need grbl to operate.
"T2Laser supports G-code, it doesn't need to be Grbl in particular. I can write an interface module for a different hardware setup if there's enough interest. The concept of being modular allows me to have a different sender / controller for other systems.
I'm also very interested in the other ports (ARM) that seems to be the future for Grbl. It sounds like the Nano version is dead once 1.0 is released."
BenCutLaser I believe does need grbl to operate, but I am decently sure @Ralph could change that if need be.
To Do List:
Remove Nano from L7 board, leave everything plugged into the board, Motors, drivers and Laser. (sshhhh,,, I have an extra if it catches on fire!)
Compare the cpu_map.h from grbl Nano to cpu_map Gnea/Grbl-Mega and draw up a map of where to run wires from and to.
Use bread board wires to make connections from the Mega's headers to the headers on the L7 board.
Double check everything.
Power it up!
Watch for any Magic Blue Smoke being let out!
Run timed tests between boards at engraving.
Many of the 3D Printer firmawares could be used to make our Laser kits work. And that opens up many boards that could be used. But most people want something that they know will work. Not something they have to fool around with to make it work. We know Grbl works for the software (BCL and T2Laser) and for the hardware that we are currently using.
There is no "Benbox" version for the Mega. If you like using Benbox software, then this post is not for you. Benbox is it's own little world. I have been playing with it on the 500mw machine and it actually works ok. I kind of ignored it at first. But it does work even if it has very few features and is relatively simple. There is no source code for the firmware to make adjustments to use the resources available on the Mega. You would get similar if not exactly the same performance as the Nano, if you could make it work!
NOTE 2: The Mega will not be here until at least Tuesday from Amazon.https://www.amazon.com/gp/product/B00PD92EJ8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1