Original Arduino Leonardo ETH
Arduino Leonardo ETH is an Arduino board based ATmega32u4 microcontroller and W5500 ethernet controller. Arduino Leonardo ETH has 20 digital I/O pins(7 of them can provide PWM out). There are a 16 MHz cyristal oscilator, a micro USB connector, a micro SD card socket, ICSP headers, an adapter input and a reset button placed on the board.
Leonardo ETH board is seperated from other Arduino boards by using ATmega32u4 microcontroller thus it needs an USB - Serial converter. Thanks to these features, Leonardo ETH can be introduced to computer as not only virtual COM port but also as peripherals such as console and mouse too. There is a Wiznet W5500 ethernet controller on the board just like Ethernet Shield 2. You may consider as this cards is like Arduino Leonardo + Ethernet Shield 2.
Features:
- Microcontroller: ATmega32u4
- Operating voltage: 5 V
- Supply voltage (recommended): 7-12 V
- Supply voltage (limits): 6-20 V
- Number of digital I/O pins: 20
- Number of PWM pins: 7
- Pins in use: 4 (SD kart CS) and 10 (W5500)
- Number of analog input pins: 12
- Max DC current for each I/O pins: 40 mA
- Max DC current for 3.3 V pin: 1 A (if supplied with an external adapter)
- Flash memory: 32 kB (ATmega32u4, 4 kB is used by bootloader)
- SRAM: 2.5 kB (ATmega32u4)
- EEPROM: 1kB (ATmega32u4)
- Clock speed: 16 MHz
Circuit Schematics of The Board and EAGLE Files:
Power:
The Leonardo ETH board can be supplied with an external power adapter, USB or optionally offered PoE (power over ethernet). When it is supplied with an external adapter or battery, using 2.1 mm width, center-positive, 7-20 V power supply is recommended. Moreover, the connectors of the power socket on the board, Vin and GND pins are short circuited in beckend.
- Vin: When an external adapter is used, the voltage of the adapter is on this pin. You can supply the board by applying 7-20 V among this pin instead of the on-board power connector.
- 5 V: The 5 V pin on the board is directly connected to the output of the regulator. To supply the board directly from this pin is not recommended due to that this way will not activate the 3.3 V and 5 V regulators on the board.
- GND: Ground pins on the board.
- 3.3 V: 3.3 V out pin from the regulator. Max. current is 50 mA.
- IOREF: It is possible to change the referance voltage of the board.
Arduino Leonardo ETH board has restarable high current protectors. Even if your computer has its own protectors for its USB ports, the protectors on the board is adjusted to reject more than 500mA. If this amount of current is reached, protectors will keep open - circuit the connection untill the short - circuit disappears.
I/O and Communication:
- Serial: 0(RX) and 1(TX) pins are used for firmware serial communication of ATmega32u4. Serial commands on Arduino Leonardo ETH is used for virtual COM port communication. You may use Serial1 commands if you want to use RX and TX pins.
- TWI: It is possible to establish a TWI / I2C commununication by using 2 (SDA) and 3 (SCL) pins and Wire library.
- External Interrupts: By using the pins 3 (Interrupt 0), 2 (interrupt 1), 0 (interrupt 2), 1 (interrupt 3) and 7 (interrupt 4) you may activate interrupts respect to logic-1 and logic-0 levels and/or rising edge or falling edge.
- PWM: Pins 3, 5, 6, 9, 10, 11 and 13 can provide 8-bit analog out using analogWrite() function.
- SPI: Can be found on ICSP headers. Unlike ATmega328p based boards like Arduino UNO, digitals pins should not be used together with SPI pins. If you have a shield using SPI communication and if there is not headers on it for ICSP pins, your shield will not work with this board.
- LED: There is a LED connected to digital pin 13. When a logic-1 signal applied, the LED blinks.
- Analog Inputs: A0 - A5 and A6 - A11 (digital 4, 6, 8, 9, 10, and 12 pins) can be used to read 10-bit analog signals. As default, the referance range of analog inputs is between 0-5 V. This range can be changed by using AREF pin and analogReferance() function.
- Reset: If logic-0 voltage level applied to this pin, the board resets itself.
The ATmega32u4 microcontroller on the board is able to communnicate via UART TTL trough 1(RX) and 1(TX) pins on 5 V logic level. Furthermore, it is possible to make a CDC (virtual COM port) communication via USB. RX and TX leds on the board blink while the board is communicating via USB. It is also possible to establish a serial communication by using SoftwareSerial library in the Arduino program and using any 2 of the digital pins on the Leonardo ETH board.
At the same time, the boards is totally compatible with the Ethernet library. Micro SD card reader is totally compatible with the SD library too. SS pin is digital pin 4.
Arduino Leonardo ETH board has automatically reset feature. Consequently, after uploading the code or before, it is not needed to push the reset button on the board. Reset function will be triggered when the virtual COM port (CDC) of the board at 1200 baud rate. When this process comes true USB connection between the board and the computer will be disconnected, microcontroller will reset itself and the bootloader works. The bootloader allows to begin uploading code to the board for approximately 8 seconds. If the automatic reset process did not start, you will need to push the reset button on the board.