===================
 Arduino Mega 2560
===================


Connection
==========

These connections are required between the Arduino Mega 2560 and the IEEE488 connector.
There are 3 different wiring diagrams, a Default one, E1 and E2:

+-----------------+-----------------+----------+
|   Arduino       | GPIB connector  | Function |
+-----+-----+-----+                 |          |
|  D  | E1  | E2  |                 |          |
+-----+-----+-----+-----------------+----------+
| A0  |  30 |  37 | 1               | DIO1     |
+-----+-----+-----+-----------------+----------+
| A1  |  32 |  35 | 2               | DIO2     |
+-----+-----+-----+-----------------+----------+
| A2  |  34 |  33 | 3               | DIO3     |
+-----+-----+-----+-----------------+----------+
| A3  |  36 |  31 | 4               | DIO4     |
+-----+-----+-----+-----------------+----------+
| D8  |  40 |  41 | 5               | EOI      |
+-----+-----+-----+-----------------+----------+
| D7  |  42 |  43 | 6               | DAV      |
+-----+-----+-----+-----------------+----------+
| D6  |  44 |  45 | 7               | NRFD     |
+-----+-----+-----+-----------------+----------+
| D16 |  46 |  47 | 8               | NDAC     |
+-----+-----+-----+-----------------+----------+
| D17 |  48 |  49 | 9               | IFC      |
+-----+-----+-----+-----------------+----------+
| D10 |  50 |  51 | 10              | SRQ      |
+-----+-----+-----+-----------------+----------+
| D11 |  52 |  53 | 11              | ATN      |
+-----+-----+-----+-----------------+----------+
| GND | GND | GND | 12              | Shield   |
+-----+-----+-----+-----------------+----------+
| A4  |  22 |  29 | 13              | DIO5     |
+-----+-----+-----+-----------------+----------+
| A5  |  24 |  27 | 14              | DIO6     |
+-----+-----+-----+-----------------+----------+
| A6  |  26 |  25 | 15              | DIO7     |
+-----+-----+-----+-----------------+----------+
| A7  |  28 |  23 | 16              | DIO8     |
+-----+-----+-----+-----------------+----------+
| D9  |  38 |  39 | 17              | REN      |
+-----+-----+-----+-----------------+----------+
| GND | GND | GND |18,19,20,21,22,23| GND      |
+-----+-----+-----+-----------------+----------+

The default layout on the Mega was chosen so as to leave pins ``A8-A15`` and the two
rows of pins at the top of the board free for expansion including for displays and other
peripherals.

Pins 16 and 17 correspond to ``Serial2``. As these have been used for controlling
signals on the GPIB bus, they cannot be used for serial communication. If
``Serial2.begin`` is added to the sketch, these pins will be enabled for serial
communication and will no longer function as GPIB control signals. In addition to the
default serial port (``RX0`` and ``TX0``), ``Serial1`` and ``Serial3`` are still
available for expansion if required. These two pins were chosen for GPIB signals as they
belong to port H along with pins 6 – 9.


Wiring diagram - default layout
-------------------------------

.. image:: /_static/wiring_mega.png


Wiring diagram - layout E1 & E2
-------------------------------

.. figure:: /_static/wiring_mega_e1e2.png
   :alt: Arduino Mega 2560 wiring diagram

   Arduino Mega 2560 wiring diagram


.. figure:: /_static/wiring_mega_e1e2_pinout.png
   :alt: Arduino Mega 2560 E1/E2 pinout

   Arduino Mega 2560 E1/E2 pinout