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Diffstat (limited to 'source/compatibility.rst')
| -rw-r--r-- | source/compatibility.rst | 48 |
1 files changed, 25 insertions, 23 deletions
diff --git a/source/compatibility.rst b/source/compatibility.rst index 848a3d3..0d6319f 100644 --- a/source/compatibility.rst +++ b/source/compatibility.rst @@ -13,17 +13,17 @@ Overview -------- The biggest difference between the Maple and most Arduino boards is -that the Maple uses a 32-bit ARM Cortex-M3 architecture chip while the -Arduinos have 8-bit Atmel AVR chips. The different instruction set -means that machine code (executable binary programs) is incompatible -between the two, and a different compiler (actually just a different -version of `gcc <http://gcc.gnu.org/>`_) is required. - -The compiler for the regular Arduino IDE is the popular -:command:`avr-gcc` package; the compiler for the Maple version of the -IDE is CodeSourcery's edition of gcc for the ARM EABI target -(:command:`arm-non-eabi-gcc`). A (preliminary) reference on -:ref:`using arm-none-eabi-gcc <arm-gcc>` is available. +that the Maple uses a 32-bit ARM Cortex-M3 architecture chip, while +the Arduinos have 8-bit Atmel AVR chips. The different instruction set +means that machine code (which makes up executable binary program) is +incompatible between the two, and a different compiler (actually just +a different version of `gcc <http://gcc.gnu.org/>`_) is required. + +The compiler for the regular Arduino IDE is the popular `avr-gcc +<http://www.nongnu.org/avr-libc/>`_ package; the compiler for the +Maple version of the IDE is CodeSourcery's edition of gcc for the ARM +EABI target (:command:`arm-non-eabi-gcc`). A (preliminary) reference +on :ref:`using arm-none-eabi-gcc <arm-gcc>` is available. The bitwidth of the processor means that the Maple can process 32-bit operations (like adding two 32-bit integers) in a single instruction, @@ -31,12 +31,12 @@ while an Arduino processor would have to split up large operations into several smaller ones. In a lot of cases 8-bit operations are plenty (integers 0-255, single characters of text, etc.), but if you're dealing with higher resolution data, the speed up could be -significant. A trade-off is that code could be larger as well; program -instructions and memory locations can be up to 32-bits each, which in -the worst case would quadruple program size. In reality, the removal -of extra instructions and fancy packing together of simple -instructions means that programs aren't much larger (or are even -smaller). +significant. + +A trade-off is that code could be larger as well; program instructions +and memory locations can be up to 32 bits each. However, removal of +extra instructions and fancy packing together of simple instructions +means that programs aren't much larger (or are even smaller). Header Numbering and Incompatibilities -------------------------------------- @@ -63,9 +63,9 @@ The incompatible hardware differences are: peripheral internally using low level configuration, but we haven't looked in to it. -* **No External Voltage Reference**: The Arduino has an Aref pin which +* **No External Voltage Reference**: The Arduino has an AREF pin which allows the use of an external ADC voltage reference; the Maple has - an extra GPIO pin (14) with PWM capability in this spot, and does + an extra GPIO pin (D14) with PWM capability in this spot, and does not allow an external voltage reference to be configured. * **EEPROM**: the Maple does not have any internal EEPROM. This @@ -93,11 +93,13 @@ differences, most of which are improvements: * :ref:`pinMode() <lang-pinmode>` **types**: any :ref:`GPIO <gpio>` (including analog pins) can be configured into one of the following - modes with a single call to ```pinMode()``: ``OUTPUT``, + modes with a single call to ``pinMode()``: ``OUTPUT``, ``OUTPUT_OPEN_DRAIN``, ``INPUT_FLOATING``, ``INPUT_PULLUP``, - ``INPUT_PULLDOWN``. Additionally, the PWM and Analog Input pins can - be configured as ``INPUT_ANALOG`` and ``PWM`` respectively. See the - :ref:`GPIO documentation <gpio>` for more information. + ``INPUT_PULLDOWN``. Additionally, the PWM pins (labeled "PWM" on the + Maple's silkscreen) can be configured in ``PWM`` and + ``PWM_OPEN_DRAIN`` modes, and the analog input pins (labeled "AIN") + can be configured in ``INPUT_ANALOG`` mode. See the :ref:`GPIO + documentation <gpio>` for more information. * :ref:`Serial port <lang-serial>` **syntax**: like the `Arduino Mega <http://arduino.cc/en/Main/ArduinoBoardMega>`_, the Maple has |