ITEAD Iteaduino Leonardo User manual

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Iteaduino Leonardo
Overview
The Iteaduino Leonardo is a microcontroller board based on
the ATmega32u4. It has 20 digital input/output pins (of which 7 can
be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal
oscillator, a micro USB connection, a power jack, an ICSP header, and
a reset button. It contains everything needed to support the
microcontroller; simply connect it to a computer with a USB cable or
power it with an AC-to-DC adapter or battery to get started.
The Iteaduino Leonardo differs from all preceding boards in that
the ATmega32u4 has built-in USB communication, eliminating the
need for a secondary processor. This allows the Leonardo to appear to
a connected computer as a mouse and keyboard, in addition to a
virtual (CDC) serial / COM port. It also has other implications for the
behavior of the board.

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Basic features
Efficient DC-DC Power supply with wide range input.
3.3V/5V Operating Voltage selection
All pins out for Sensor and Servo
UART/IIC interface breakout
All electronic brick socket are broken out
Specifications
Microprocessor
ATmega32U4
PCB size
68.58mm X 58.42mm X 1.6mm
Indicators
Power,TX,RX,L
Power supply(recommended)
7-23V DC
Power supply(limits)
23 VDC (max)
Communication Protocol
UART,SPI,IIC
Clock Speed
16MHz
RoHS
Yes
Electrical Characteristics
Specification
Min
Type
Max
Unit
Input voltage
7
-
23
VDC
Operating Voltage
-
3.3/5
-
VDC
DC Current per I/O Pin
-
40
-
mA

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Hardware
Digital/Servo Interface: D0~D13 pin
Sensor Interface: A0 A1 A2 A3 A4 A5 pin
Pin Map
Index
Name of Arduino
Alternate Function
Pin of Atmega32u4
1
D0
UART DIN
PD2
2
D1
UART DOUT
PD3
3
D2
IIC_SDA
PD1
4
D3
IIC_SCL/PWM
PD0
5
D4
External Interrupt 0/A6
PD4
6
D5
External Interrupt 1/PWM
PC5
7
D6
PWM
PD7
8
D7
A7
PE6
9
D8
A8
PB4
10
D9
PWM/A9
PB5

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11
D10
PWM/A10
PB6
12
D11
PWM
PB7
13
D12
A11
PD6
14
D13
PWM
PC7
15
A0
PF7
16
A1
PF6
17
A2
PF5
18
A3
PF4
19
A4
PF1
20
A5
PF0
Power Supply
The Arduino Leonardo can be powered via the micro USB connection or with an
external power supply. The power source is selected automatically.
External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or
battery. The adapter can be connected by plugging a 2.1mm center-positive plug
into the board's power jack. Leads from a battery can be inserted in the Gnd and Vin
pin headers of the POWER connector.
The board can operate on an external supply of 7 to 23 volts. If supplied with less
than 7V, however, the 5V pin may supply less than five volts and the board may be
unstable.
The power pins are as follows:
VIN. The input voltage to the Iteaduino board when it's using an external power
source (as opposed to 5 volts from the USB connection or other regulated power
source). You can supply voltage through this pin, or, if supplying voltage via the
power jack, access it through this pin.
5V. The regulated power supply used to power the microcontroller and other
components on the board. This can come either from VIN via an on-board regulator,
or be supplied by USB or another regulated 5V supply.
3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current
draw is 250 mA.
GND. Ground pins.
IOREF. The voltage at which the i/o pins of the board are operating (i.e. VCC for the
board). This is 5V on the Iteaduino Leonardo.

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Memory
The ATmega32u4 has 32 KB (with 4 KB used for the bootloader). It also has 2.5 KB
of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM
library).
Input and Output
Each of the 20 digital i/o pins on the Uno can be used as an input or output,
using pinMode(), digitalWrite(), anddigitalRead() functions. They operate at 5 volts.
Each pin can provide or receive a maximum of 40 mA and has an internal pull-up
resistor (disconnected by default) of 20-50 kOhms. In addition, some pins have
specialized functions:
Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data
using the ATmega32U4hardware serial capability. Note that on the Leonardo,
the Serial class refers to USB (CDC) communication; for TTL serial on pins 0 and 1,
use the Serial1 class.
TWI: 2 (SDA) and 3 (SCL). Support TWI communication using the Wire library.
External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt
on a low value, a rising or falling edge, or a change in value. See
the attachInterrupt() function for details.
PWM: 3, 5, 6, 9, 10, 11, and 13. Provide 8-bit PWM output with
the analogWrite() function.
SPI: on the ICSP header. These pins support SPI communication using the SPI
library. Note that the SPI pins are not connected to any of the digital I/O pins as they
are on the Uno, They are only available on the ICSP connector. This means that if
you have a shield that uses SPI, but does NOT have a 6-pin ICSP connector that
connects to the Leonardo's 6-pin ICSP header, the shield will not work.
LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH
value, the LED is on, when the pin is LOW, it's off.
Analog Inputs: A0-A5, A6 - A11 (on digital pins 4, 6, 8, 9, 10, and 12). The
Leonardo has 12 analog inputs, labeled A0 through A11, all of which can also be
used as digital i/o. Pins A0-A5 appear in the same locations as on the Uno; inputs
A6-A11 are on digital i/o pins 4, 6, 8, 9, 10, and 12 respectively. Each analog input
provides 10 bits of resolution (i.e. 1024 different values). By default the analog
inputs measure from ground to 5 volts, though is it possible to change the upper end
of their range using the AREF pin and the analogReference() function.
There are a couple of other pins on the board:

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AREF. Reference voltage for the analog inputs. Used with analogReference().
Reset. Bring this line LOW to reset the microcontroller. Typically used to add a reset
button to shields which block the one on the board.
Communication
The Iteaduino Leonardo has a number of facilities for communicating with a
computer, another Arduino, or other microcontrollers. The ATmega32U4 provides
UART TTL (5/3.3V) serial communication, which is available on digital pins 0 (RX)
and 1 (TX). The 32U4 also allows for serial (CDC) communication over USB and
appears as a virtual com port to software on the computer. The chip also acts as a
full speed USB 2.0 device, using standard USB COM drivers. On Windows, a .inf file
is required. The Arduino software includes a serial monitor which allows simple
textual data to be sent to and from the Arduino board. The RX and TX LEDs on the
board will flash when data is being transmitted via the USB connection to the
computer (but not for serial communication on pins 0 and 1).
A Software Serial library allows for serial communication on any of the Iteaduino
Leonardo's digital pins.
The ATmega32U4 also supports I2C (TWI) and SPI communication. The Arduino
software includes a Wire library to simplify use of the I2C bus. For SPI
communication, use the SPI library.
The Iteaduino Leonardo appears as a generic keyboard and mouse, and can be
programmed to control these input devices using the Keyboard and Mouse classes.
Programming
The Iteaduino Leonardo can be programmed with the Arduino software . Select
"Arduino Leonardo from the Tools > Board menu (according to the microcontroller
on your board).
The ATmega32U4 on the Iteaduino Leonardo comes pre-burned with
a bootloader that allows you to upload new code to it without the use of an external
hardware programmer. It communicates using the AVR109 protocol.
You can also bypass the bootloader and program the microcontroller through the
ICSP (In-Circuit Serial Programming) header.

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Automatic (Software) Reset and Bootloader
Initiation
Rather than requiring a physical press of the reset button before an upload, the
Iteaduino Leonardo is designed in a way that allows it to be reset by software
running on a connected computer. The reset is triggered when the Leonardo's
virtual (CDC) serial / COM port is opened at 1200 baud and then closed. When this
happens, the processor will reset, breaking the USB connection to the computer
(meaning that the virtual serial / COM port will disappear). After the processor
resets, the bootloader starts, remaining active for about 8 seconds. The bootloader
can also be initiated by pressing the reset button on the Leonardo. Note that when
the board first powers up, it will jump straight to the user sketch, if present, rather
than initiating the bootloader.
Because of the way the Iteaduino Leonardo handles reset it's best to let the Arduino
software try to initiate the reset before uploading, especially if you are in the habit
of pressing the reset button before uploading on other boards. If the software can't
reset the board you can always start the bootloader by pressing the reset button on
the board.
USB Over-current Protection
The Iteaduino Leonardo has a PTC that protects your computer's USB ports from
shorts and over-current. Although most computers provide their own internal
protection, the fuse provides an extra layer of protection. If more than 500 mA is
applied to the USB port, the fuse will automatically break the connection until the
short or overload is removed.
Physical Characteristics
The maximum length and width of the Leonardo PCB are 68.58 and 58.42 milimeter
respectively, with the USB connector and power jack extending beyond the former
dimension. Four screw holes allow the board to be attached to a surface or case.
Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even
multiple of the 100 mil spacing of the other pins.

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Links and References
-ITead Studio Site: iteadstudio.com
- Arduino site: arduino.cc
- Getting started with Arduino: arduino.cc/en/Guide/Windows
Revision History
Rev.
Description
Release date
v1.0
Initial version
2012-07-17