Maple Language Reference¶
The Maple can be programmed in the Wiring language, which is the same language used to program the Arduino boards.
C or C++ programmers may wish to skip to the Note for C/C++ Hackers or the Unix Toolchain Quickstart.
Contents
Looking for Something Else?
- See the Maple Library Reference for extra built-in libraries.
- If you want to use C or C++, see the Unix Toolchain Quickstart.
- If you’re looking for something from the C standard library (like atoi(), for instance, see this FAQ.
- Low-level details are in libmaple and this page’s Recommended Reading.
Maple Language Reference¶
This table is a summary of the most important language features. See the Complete Language Index for a complete listing.
| Structure | Variables | Functions |
|---|---|---|
|
Control Structures Further syntax
Arithmetic Operators Comparison Operators
Boolean Operators Pointer Operators Bitwise Operators Compound Operators
Keywords |
Constants Data Types
Conversion Variable Scope & Qualifiers Utilities |
Digital I/O
Analog I/O
Advanced I/O
Time Math Trigonometry Random Numbers Bits and Bytes
External Interrupts Interrupts Communication |
Missing Arduino Features¶
analogReference()
It is not possible to implement this function on the Maple hardware. It will be possible on the upcoming Maple Native.
word
Readers familiar with the Arduino environment may notice that the word datatype is missing from the above table’s list of data types. We chose not to provide the word data type on the Maple. If you want a 16-bit unsigned integer, use the uint16 type instead.
While the Maple has 32-bit words, the word size on an Arduino board is only 16 bits, and code that uses the word type is likely to rely on that fact.
By not supporting word, you’ll get a compile error when porting Arduino code to the Maple instead of potentially weird, hard-to-debug runtime behavior.
If you really must have word, you can include the following typedef in your program:
typedef uint16 word;
Unimplemented Arduino Features¶
The following Wiring/Arduino features are currently unimplemented on the Maple.
C++ for Maple¶
If you haven’t programmed in C++, or if you just need to jog your memory, you may want to check out our Language Index. It provides some introductory coverage of programming ideas and C++.
Note for C/C++ Hackers¶
This is a note for programmers comfortable with C or C++ who want a better understanding of the differences between C++ and the Wiring language.
The good news is that the differences are relatively few; Wiring is just a thin wrapper around C++. Some potentially better news is that the Maple can be programmed using a standard Unix toolchain, so if you’d rather stick with gcc, make, and friends, you can. If you’re using the Unix toolchain and want to skip past the Wiring conveniences and get straight to registers, you are encouraged to move on to the libmaple documentation.
A sketch is the IDE’s notion of a project; it consists of one or more files written in the Wiring language, which is mostly the same as C++. The major difference between the two is that in Wiring, it’s not necessary to declare global functions before they are used. That is, the following is valid Wiring, and f() returns 5:
int f() {
return g();
}
int g() {
return 5;
}
All of the files in a sketch share the same (global) namespace. That is, the behavior is as if all of a sketch’s files were part of the same translation unit, so they don’t have to include one another in order to access each other’s definitions. The only other major difference between Wiring and C++ is that Wiring doesn’t support dynamically allocated memory – that is, new and delete won’t work. As of May 16, 2012, Maple only has 20 KB RAM, anyway, so it’s doubtful that static allocation is not what you want.
The Wiring language also does not require you to define your own main method (in fact, we currently forbid you from doing so). Instead, you are required to define two functions, setup and loop, with type signatures
void setup(void);
void loop(void);
Once a sketch is uploaded to a Maple and begins to run, setup() is called once, and then loop() is called repeatedly. The IDE compilation process proceeds via a source-to-source translation from the files in a sketch to C++.
This translation process first concatenates the sketch files, then parses the result to produce a list of all functions defined in the global scope. (We borrow this stage from the Arduino IDE, which in turn borrows it from Wiring. It uses regular expressions to parse C++, which is, of course, Bad and Wrong. In the future, we’ll do this correctly, using a better parser. Until then, you have our apologies.) The order in which the individual sketch files are concatenated is not defined; it is unwise to write code that depends on a particular ordering.
The concatenated sketch files are then appended onto a file which includes WProgram.h (which includes the wirish and libmaple libraries, and declares setup() and loop()), and then provides declarations for all the function definitions found in the previous step. At this point, we have a file that is a valid C++ translation unit, but lacks main(). The final step of compilation provides main(), which behaves roughly like:
int main(void) {
// Call libmaple's built-in initialization routines
init();
// Perform the user's initialization
setup();
// Call user loop() forever.
while (true) {
loop();
}
}
(The truth is a little bit more complicated, but not by much).
As an example, consider a sketch with two files. The first file contains setup() and loop():
int the_pin;
void setup() {
the_pin = choose_a_pin();
pinMode(the_pin, OUTPUT);
}
void loop() {
togglePin(the_pin);
}
The second file contains the (not very useful) implementation for choose_a_pin():
int choose_a_pin() {
return random(5, 15);
}
Then the results of the concatenation process might be
int the_pin;
void setup() {
the_pin = choose_a_pin();
pinMode(the_pin, OUTPUT);
}
void loop() {
togglePin(the_pin);
}
int choose_a_pin(void);
int choose_a_pin() {
return random(5, 15);
}
Which could plausibly be turned into the final source file
#include "WProgram.h"
void setup(void);
void loop(void);
int choose_a_pin(void);
int the_pin;
void setup() {
the_pin = choose_a_pin();
pinMode(the_pin, OUTPUT);
}
void loop() {
togglePin(the_pin);
}
int choose_a_pin(void);
int choose_a_pin() {
return random(5, 15);
}
int main() {
init();
setup();
while (true) loop();
}
Recommended Reading¶
Your board’s Board Hardware Documentation page
- ST Documentation:
- Reference Manual RM0008 (PDF). This is the most important reference work on the STM32 line, and covers the low-level hardware capabilities and interfaces in great detail.
- Programming Manual (PDF). This is an assembly language and register reference for the STM32 line.
- ARM Documentation:
- Cortex-M3 Technical Reference Manual, Revision r1p1 (PDF). This ARM manual specifies much of the the Cortex M3 Architecture, including instruction timings.
