Peter OM5ADX started making development boards for ATMEL processors. Today we will present you one of them - AVR20 designed for ATMEL with twenty pins. In addition, AVR28 (28-pin) boards are also available, and boards for MICROCHIP PIC 16F84/628 18 pi MCU, 28 pin MCU and 40 pin MCU are already in development. There will also be a board with color in the near future LCD 128*128 pixels + keys + SD CARD slot + EEPROM + BUZZER
The AVR20 is a development board designed for your wiring prototypes and firmware development for ATMEL AVR series processors with 20 pins.
Why AVR20?
The AVR20 has an RS232 connector and a circuit that can connect your AVR processor to another device or PC with an RS232 interface. At the output of the RS232 circuit there are 4 input-output lines, TX, RX, CTS and an optional RTS or DTR signal via a jumper.
The pin labeled RX is an output and must be connected to the processor pin labeled RX. The pin labeled TX is an input and must be connected to the processor pin labeled TX. The standard MAX232 circuit in the socket is for a 5V power supply, if you use the processor in 3.3V mode, it is necessary to replace this circuit with a MAX3232 type that works at 3.3V.
The ICSP connector on the board allows connecting the programmer and subsequent programming of the processor. The connector and pin connections are described below.
ATTENTION: all programmers that provide 5v power to the application can be used, but in this case we do not connect the power to the AVR20 board!
Power supply it contains a power connector, a diode bridge that allows both AC and DC voltage to be connected to the connector and at the same time protects the board against voltage reversal. The input voltage can be in the range of +7.5V - 15V DC and 6 - 12V AC.
The voltage regulator is solved with the LM317 circuit (adjustable voltage regulator), the power supply of the processor and circuits can be selected with a jumper, i.e. +5V or +3.3V.
The oscillator is designed with a 10MHz crystal for the best possible processor speed. RESET – the circuit is designed as an RC circuit with a button, if necessary, a reset circuit DS1813 can be installed for a voltage of 5V.
Doska AVR20 je osadená jedným užívateľským tlačidlom pripojeným na pin 6 procesora. Keď je vstup procesora nastavený ako vstup, potom ak je tlačidlo stlačené tak sa číta logická „0“ a logická „1“ pokiaľ tlačidlo zatlačené nie je.
The power LED signals power at the input of the board.
Board description:
- STK200 compatible ICSP 5x2 pin connector for in-circuit programming
- RS232 circuit with MAX232
- DIL20 socket for the processor
- Crystal 10MHz
- Power LED
- User button
- Reset button (optional DS1813 reset circuit)
- Power connector, AC and DC power supply 7-15V accepted
- Optional +3.3V / +5V power supply circuit (3.3V if the jumper is connected)
- Wired all processor pins to buses
- GND bus
- Vcc bus
- 4 mounting holes 3.3 mm • FR-4, 1.5 mm, green non-solder mask, blue description
- Dimensions 100×80 mm
Wiring:
ICSP connector:
RS232 cable for AVR20 board:
The boards are delivered completely assembled and tested, they contain a standard ISP connector, RS-232 interface, power 5V/3.3V, reset and interrupt buttons, packed in an antistatic bag and in a cardboard box with an SK or ENG manual. All boards are completely hand-mounted and soldered in the best quality. The circuit board is with a non-soldering mask and a description of the parts.
The price of the AVR20 and AVR28 boards is 690 Sk
Data RS232 cable for 80 Sk
Peter, OM5ADX om5adx@wmx.sk
+421 908 737 544