My project is finished (for the present)
This is a new Moving Message Display with a LPC2138 and 8(16) x 5x7 led matrix, working.
It uses a new and fast algorithm, written in C.
It is modular: it uses one or two same 8 char display unit(s).
Online commands (via rs232, in Virtual Terminal)
- scrolling by pixel or by character or by graphic - pause/continue scrolling - on/off one pixel gap between fonts - home function (back to the begin) - max. 127 chars displayable text - - - stored in the memory - scrolling speed up/down - single step left/right - ASCII char test - multi language characters (also full American) - default settings via switches - get/store settings from/to memory
Latest addition
- - - last typed char is deletable (backspace function), this was very difficult to code.
I'm going to attach here the two projects (for 8 and 16 chars) with the hex firmware only, beacuse I wrote the program in C but with many (70%) hard and hand optimalisation in C (for the speed). It is not a human readable program, sorry...
Please study also my next posts at this thread if you want to build this!
Try it!
About the source look at my next posts here!
The standard has always defined this as only a hint to the compiler - compilers have never had to take any notice of it!
Not true. They've always been required to disallow taking the address of such variables:
The operand of the unary & operator shall be either a function designator, the result of a [] or unary * operator, or an lvalue that designates an object that is not a bit-field and is not declared with the register storage-class specifier
[C99 6.5.3.2 paragraph 1, emphasis mine]
And since defining arrays with storage class register causes undefined behaviour, you can't get around this by passing the name of an array, either.
defining arrays with storage class register causes undefined behaviour,
Ooops, that was an incorrect interpretation. It's using the name of a register-class array as an implied pointer to its first element that causes undefined behaviour, not defining such an array. OTOH, since that and 6.5.3.2 basically kill all useful things one can do with an array, there's no point defining one.