ATMEGA8A Tutorial Board A

Revision	Description
1.0	Completed initial design of evaluation board.
1.1	Added series resistor to external reset for MCU. Added series resistor to potentiometer for short-circuit protection. Added series resistor to NE555 output for short-circuit protection. Updated ISP-10 footprint to ISP-6. Updated resistor footprint.
1.2	Added company logo to top silkscreen. Changed vertical DIP switch to horizontal.

Getting Started

Prerequisites

# install build tools
sudo apt-get install binutils gcc-avr avr-libc uisp avrdude flex byacc bison

Building

Execute the following commands in the software-design folder,

USBasp

# Windows 10
cmake --preset default
cmake --build . --preset default
# Ubuntu
cmake --preset default
cmake --build --preset default

AVRISP MKII

# Windows 10
cmake --preset avrispii
cmake --build . --preset avrispii
# Ubuntu
cmake --preset avrispii
cmake --build --preset avrispii

Targets

After building the default preset the following targets will be made available in the generated makefile,

# flash command for a simple blink program
make flash-blink-sync
make disassemble-blink-sync

# enables the use of an external 16MHz clock source
make fuse

Modules

7 Segment

Diagram	Description
	The 7-segment display uses all of Port D for setting the individual segments The lower nibble of Port C is used to multiplex the currently active digit The digits are numbered from left to right when the decimal point is positioned correctly relative to the users point of view All segments and selection pins are active low

Microcontroller	D0	D1	D2	D3	D4	D6	D7	C0	C1	C2	C3
7-segment	F	C	A	G	B	E	DEC	Digit 1	Digit 2	Digit 3	Digit 4

Value	D7	D6	D5	D4	D3	D2	D1	D0	HEX
0	1	0	0	0	1	0	0	0	0x88
1	1	1	1	0	1	1	0	1	0xED
2	1	0	0	0	0	0	1	1	0x83
3	1	1	0	0	0	0	0	1	0xC1
4	1	1	1	1	0	1	0	0	0xE4
5	1	1	0	1	1	0	0	0	0xD0
6	1	0	0	1	1	0	0	0	0x90
7	1	1	1	0	1	0	0	1	0xE9
8	1	0	0	0	0	0	0	0	0x80
9	1	1	1	0	0	0	0	0	0xE0

LED

Two active high LEDs located on pins B1 and B2 of the microcontroller.

Potentiometer

A 50k linear potentiometer connected to pin C4. The potentiometer has two 1K resistors in series for current limiting & protection. It is expected that the analog readout on the potentiometer will never reach GND or VCC (but will come close).

Timer

The NE555 chip feeds into the input capture pin (B0) of the microcontroller. The output frequency ranges from 100Hz~1000Hz by setting the individual DIP switches.

Specifications

Rev 1.0

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Rev 1.1

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Rev 1.2

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