[2.0.x] LPC1768 Use flash memory to emulate eeprom

[gloomyandy]

Description

Use a sector of the LPC flash memory to emulate eeprom storage.

Benefits

This allows LPC1768 systems to store system parameters without needing an SD card present in the system. An extra benefit of this is that when attached to a Windows system the SD card is not unmounted/mounted each time the system parameters are loaded/stored (which it seems can result in a system freeze).

Related Issues

#11315

[Roxy-3D]

Good idea! Very nice!

[p3p]

beat me to it (not so difficult ;)) your implementation will more than likely need pulled into https://github.com/p3p/pio-framework-arduino-lpc176x as the arduino EEPROM implementation if that's ok

@Roxy-3D was actually the way it was originally before things were merged into Marlin, but I decided (maybe foolishly ^^) that it was better to use the sd card so we didn't have to worry about flash endurance, we had a discussion about it long ago, using the sd card has caused more problems than it's worth at this point though.

[Roxy-3D]

Yes... I remember. It probably was good and smart to use the SD-Card initially. Besides the endurance issue... Just to make sure bugs and such would not erase the bootstrap or corrupt any fuses in the part.

But now things are stable enough... It will be good to ditch the SD-Card!

[p3p]

And also don't you love it when the tool chain updates and decides to change the defines passed to the compiler, though it does remind me we need to add the F_CPU to the pins files to differentiate the LPC1768 and LPC1769 boards

[gloomyandy]

Feel free to integrate it into whatever makes most sense! I assume that the Travis issues will get fixed, or do I need to do anything for that?

[p3p]

yea that's for me to fix, just contemplating on whether to require F_CPU to be defined in all LPC176x pins files or default it to 100Mhz and only redefine for none 100Mhz boards

[GadgetNutt]

I vote define per board.

[Roxy-3D]

I vote define per board.

I think I agree. Already... 100 MHz boards are losing popularity.

[gloomyandy]

I think having it per board makes it clear that you may need to define it. Having default values is good sometimes, but it can make it hard to see exactly what you may need to define for a new board. As a good example it was not very obvious (to me at least) when I was browsing the source on the web how/where E2END was defined for the LPC1768 (easy to find using Atom or some other ide of course).

[forkoz]

lol, Oh man, right after I fixed my USB issue :0