ITT AVR Laboratory Node Hardware Reference

Controller module ATmega2561 v1.x

The main module is a controller development board (controller board) equipped with the AVR ATmega2561 microcontroller. In addition to the microcontroller, the board consists of several peripherals, voltage stabilizer, connectors, JTAG programmer, Ethernet, SD memory card slot. The controller board has the following features:

  • ATmega2561-16AU microcontroller
    • 8-channel 10-bit A/D converter
    • 256 kB Flash memory (program memory)
    • 4kB EEPROM memory (data memory)
    • 6 channel programmable PWM
  • Integrated JTAG programmer (based on FTDI2232)
  • 14,7456 MHz clock
  • Ethernet module with RJ45 connector
  • SD memory card slot
  • Status LED (PB7)and Power LED
  • Programmable button (PC2) and reset button
  • All Atmega signals available on three connectors (1: ports D, B, E; 2: ports G, C, A; 3: port F with ADC I/O lines)
  • 2,1 mm power socket
  • Automatic power switch USB or external power supply
  • Built-in voltage stabilizer, with 5 V and 3,3 V output
Controller module

The module is equipped with a AC/DC rectifier circuit and a LDO voltage stabilizer (with low dropout) -an external feeder with voltage stabilization is not needed. The module can be powered with a step down transformer with an output voltage which is greater than 6 volts and lower than 15 volts. In order to reduce power losses it is recommended to use power supply between 6-9V. The POWER LED signalizes a connected feed (“POWER” description on the board). All ATmega2561 signals are available on three connectors on the edge of the board. Connectors pin assignment is described in the next part of this instruction. It includes full descriptions of ATmega2561 pins and their alternative functions. The module is equipped with a microprocessor reset circuit (when power on) and a reset button for a microprocessor restart. A microprocessor can be programmed with an on-board JTAG programmer over USB or with an ISP interface. To the seventh pin of port B (named as PB7) the status LED (described as PB7 on the board) is connected. This LED can be used as a status indicator of application software. Low state on PB7 pin causes the status LED to be lit. The module is equipped with SD memory card slot, where it can be used as a standard microSD memory card. The memory card is connected to the microcontroller via the ISP interface and can be used to store data where data must be maintained even if the power supply is removed.

Components on the Controller board

Connector Pins and Functions

NrPinAlternative function / Description
1VCC- +5 V
3REFAREFAnalog Reference Voltage For ADC
5PF0ADC0ADC Input Channel 0
7PF1ADC1ADC Input Channel 1
9PF2ADC2ADC Input Channel 2
11PF3ADC3ADC Input Channel 3


NrPinAlternative function / Description
1 PD7T2 Timer/Counter2 Clock Input
2 PD6T1 Timer/Counter1 Clock Input
3 PD5XCK1 USART1 External Clock Input/Output
4 PD4IC1 Timer/Counter1 Input Capture Trigger
5 PD3INT3/TXD1 External Interrupt3 Input or UART1 Transmit Pin
6 PD2INT2/RXD1 External Interrupt2 Input or UART1 Receive Pin
7 PD1INT1/SDA External Interrupt1 Input or TWI Serial Data
8 PD0INT0/SCL External Interrupt0 Input or TWI Serial Clock
9 VCC- +5V
11PB7OC0A/OC1C/PCINT7Output Compare and PWM Output A for Timer/Counter0, Output Compare and PWM Output C for Timer/Counter1 or Pin Change Interrupt 7
12PB6OC1B/PCINT6Output Compare and PWM Output B for Timer/Counter1 or Pin Change Interrupt 6
13PB5OC1A/PCINT5Output Compare and PWM Output A for Timer/Counter1 or Pin Change Interrupt 5
14PB4OC2A/PCINT4Output Compare and PWM Output A for Timer/Counter2 or Pin Change Interrupt 4
15PB3MISO/PCINT3SPI Bus Master Input/Slave Output or Pin Change Interrupt 3
16PB2MOSI/PCINT2SPI Bus Master Output/Slave Input or Pin Change Interrupt 2
17PB1SCK/PCINT1SPI Bus Serial Clock or Pin Change Interrupt 1
18PB0SS/PCINT0SPI Slave Select input or Pin Change Interrupt 0
19PE7INT7/IC3/CLK0 External Interrupt 7 Input, Timer/Counter3 Input Capture Trigger or Divided System Clock
20PE6INT6/T3 External Interrupt 6 Input or Timer/Counter3 Clock Input
21PE5INT5/OC3CExternal Interrupt 5 Input or Output Compare and PWM Output C for Timer/Counter3
22PE4INT4/OC3BExternal Interrupt4 Input or Output Compare and PWM Output B for Timer/Counter3
23PE3AIN1/OC3AAnalog Comparator Negative Input or Output Compare and PWM Output A for Timer/Counter3
24PE2AIN0/XCK0Analog Comparator Positive Input or USART0 external clock input/output
25PE1PDO/TXD0 ISP Programming Interface Data Output or USART0 Transmit Pin
26PE0PDI/RXD0/INT8 ISP Programming Interface Data Input, USART0 Receive Pin or Pin Change Interrupt 8

NrPinAlternative function / Description
1 GND- Gnd
2 VCC- +5 V
3 PA0AD0External memory interface address and data bit 0
4 PA1AD1External memory interface address and data bit 1
5 PA2AD2External memory interface address and data bit 2
6 PA3AD3External memory interface address and data bit 3
7 PA4AD4External memory interface address and data bit 4
8 PA5AD5External memory interface address and data bit 5
9 PA6AD6External memory interface address and data bit 6
10PA7AD7External memory interface address and data bit 7
11PG4TOSC1RTC Oscillator Timer/Counter2
12PG5OC0BOutput Compare and PWM Output B for Timer/Counter0
13PG2ALEAddress Latch Enable to external memory
14PG3TOSC2RTC Oscillator Timer/Counter2
15PC6A14External Memory interface address bit 14
16PC7A15External Memory interface address bit 15
17PC4A12External Memory interface address bit 12
18PC5A13External Memory interface address bit 13
19PC2A10External Memory interface address bit 10
20PC3A11External Memory interface address bit 11
21PC0A8 External Memory interface address bit 8
22PC1A9 External Memory interface address bit 9
23PG0WR Write strobe to external memory
24PG1RD Read strobe to external memory
263V3- +3,3 V

User Interface module

The User Interface module is designed for simple tasks and basic process control. Module has three push-buttons and three LEDs, which can be used as digital inputs and outputs of microcontroller. Additionally to simple LEDs the module is equipped with 7-segment indicator, graphical LCD display, alphanumeric LCD outputs and a buzzer. User Interface module is handy to use along with other modules enabling to control the output device behavior, like motors and display the sensor readings.

Module features:

  • Three LEDs: green, yellow and red;
  • Three push-buttons;
  • 7-segment indicator;
  • Graphical LCD;
  • Alphanumeric LCD connector;
  • Buzzer;

Electrical connections

User Interface module is connected to Controller module to ports PA/PC/PG, which includes the 8-pin ports PA and PC and 6-pin port PG.

User Interface module is equipped with three buttons S1, S2, S3 which are connected to ports PC0, PC1, PC2 accordingly. The other end of buttons are connected through the resistors to ground (logical 0). LED1, LED2 and LED3 on the module are connected to the ports PC3, PC4, PC5 accordingly. The anodes of LEDs are connected to the supply (logical 1).

Schematics of buttons and LEDs

User Interface module is equipped with 7-segment indicator, which is connected to the microcontroller ports through the driver A6275. Driver data bus (S-IN) is connected to pin PC6, clock signal (CLK) to the pin PC7 and latch signal (LATCH) to pin PG2.

Schematics of 7-segment indicator

The graphical LCD display on the module is connected to port PA. In parallel the same port has external connector where all pins are aligned according to the standard 2 x 16 alphanumeric LCD 4 bit control. The user can choose whether to use the graphical or alphanumeric LCD. It is not possible to use both at the same time. The graphical LCD's background lighting can be logically controlled by the software. The back-light intensity of the alphanumeric LCD is regulated with on-board resistor and graphical LCD back-light can be controlled by the software. Both LCD displays are connected to port PA but only one at a time can be used. When selecting the alphanumeric LCD the jumper should be removed to avoid random control of graphical LCD background light.

Schematics of LCD

The buzzer is connected with controller board's pin PG5 and with Vcc. It's possible to generate sound with Robotic Homelab library or with your own software.

Schematics of buzzer


Combo module

Combo module is used in this remote Laboratory to power the motors and connect external sensors.

Combo module is able to drive following motors:

  • 4 x DC motors
  • 1 x Stepper
  • 2 x Servomotor

Connect following sensors:

  • 4 x analog
  • 4 x digital
  • 2 x coder
  • 8x digital inputs trough parallel to serial converter

Use the following communication interfaces:

  • UART (3,3 or 5 V )
  • ZigBee / Bluetooth / RFID / WiFi / GPS wireless communication module
Combo board with XBee module

Electrical connections

Combo board is connected with controller using PA-PB-PC-PD-PE-PF ports. DC and stepper motor feeds come from external power cord, servo motors feed comes trough 5V voltage regulator also from external power cord. Motors power circuit is separated from controller's power circuit. If external power feed is correctly connected to the Combo board the green PWR led will lit.

DC motors

DC motors is connected to the DC group of pins. Every pair of pins can control 1 dc motor, thus it's possible to manipulate 4 dc motors. Combo board uses bd6226fp H-bridge to control dc motors. It's possible to manipulate some other device, what can be controlled digitally and it's current is smaller than 1 A and voltage does not exceed 18 V, beside dc motor with DC pins (Piezoelectric generator, relay etc).

DC motor connection scheme
AVR pin Signal AVR pin Signal
PB4 Motor 1 A PD6 Motor 3 A
PB7 Motor 1 B PD7 Motor 3 B
PD0 Motor 2 A PD4 Motor 4 A
PD1 Motor 2 B PD5 Motor 4 B

Stepper motor

Stepper connection scheme


Servo is connected to Servo group of pins. Ground wire is connected to the GND pin which is the pin nearest to the board edge. It's possible to use 2 servomotors at once. Signal pins on the Combo module is directly connected to the controller's timer's output pins.

Servomotor connection scheme
AVR pin Signal Socket
PB5(OC1A) PWM1 Top
PB6(OC1B) PWM2 Bottom


ADC sensor inputs

Combo module has 4 ADC input pins, every ADC input pin forms a group with Vcc (+5 V) and ground which is marked as GND, that makes them ideal to use to connect analog sensors.

Analog sensor inputs scheme
AVR pin Signal Socket
PF0(ADC0) ADC0 Top
PF1(ADC1) ADC1 Bottom
PF2(ADC2) ADC2 Top
PF3(ADC3) ADC3 Bottom

Digital inputs

Combo module has 4 groups of pins where to connect digital sensors. Every group consist of +5 V also called Vcc, ground also called GND and signal pin.

Digital sensor connecting scheme
AVR pin Signal Socket
PE2(XCK0/AIN0) PE2 Top
PE3(OC3A/AIN1) PE3 Bottom
PE4(OC3B/INT4) PE4 Top
PE5(OC3C/INT5) PE5 Bottom

Digital serial input

Combo module has with 8 input pins parallel in serial out shift register 74HC/HCT165, what is able to read in 8 digital signals and convert it to 8 bit digital number. Those inputs are suitable for line follower applications.

Shift register connection scheme, odd pins are on top
AVR pin Signal
PA7(AD7) Q7
PC7(A15) CP


Coder connection scheme
AVR pin Signal
PE6 Coder 1
PE7 Coder 2
en/iot-open/practical/hardware/ittgroup/atmel.txt · Last modified: 2024/04/20 07:41 by pczekalski
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