The Boot Board [Product Link] is a development board created for 8-bit AVR microcontrollers (especially AtMega8) with motor driver circuit and DTMF decoder on it.
- Atmega8 Microcontroller
- Inbuilt boot loader
- 23 general purpose I/O pins
- 3 PWM outputs
- 6 analog inputs
- 4 tactile push buttons
- 1 L293D motor driver with LED indication
- One 4 bit DTMF decoder IC MT8870
- 16 MHz clock speed
- USB connection
- Power jack
- ICSP header
- Reset button
- VCC and GND headers
Boot Board [Product Link] is low cost solution for the development of 8-bit AVR microcontroller, Atmega8. It comes with inbuilt HID bootloader so there is no need to buy any external bootloading device. it also provides commonly used motor driver IC L293D and a DTMF chip MT8870 for cell phone applications.
Boot Board also supports external USB programmer in case of internal programmer failure. It is a perfect and cost effective learning kit for hobbyist and engineers.
Motor Driver Circuit
This section involves the L293D IC for motor driving applications. The 4 input pins of this IC are connected to PB1-PB4 with individual LED indication.
The 4 output pins are mentioned on the board as MOTOR1 and MOTOR2 (on either side of the L293D chip)
DTMF (Dual-tone Multi-frequency) is a technique used by the mobile phone buttons. Each button has a unique frequency and this IC decodes it. It requires a signal input which can give by connecting a 3.5 mm jack to the cell phone and the corresponding 2 wires to the DTMF terminals (as mentioned on the board).
This gives a 4 bit decoded output which you can get from DO,D1,D2,D3 header pins (below the DTMF IC). This data can further be used to detect which button was pressed and do the corresponding job.
Note: DTMF only works with the keypad buttons on the mobile while you attend/dial a call so you either need to call someone or there are many applications available online, download them and enjoy!
There are 23 general purpose I/O pins available on this board out of which 3 pins(PB1,PB2&PB3) can also be used for PWM purposes and 6 pins (PC0-PC5) for ADC purposes.
Connect the boot board with a A-to-B type USB cable and another end to a computer. Computer will automatically recognize this board. Now download a software ,HID Boot Flash [Link], which will help in burning the HEX file into this board. Hex file can be generated from any Embedded ‘C’ coding software like AVR Studio, Eclipse, Kiel etc.
This board can be powered either by the USB cable or by a DC adapter (ranging 8-20V). The 7805 voltage regulator IC will automatically regulate the external voltage to 5V. While using the L293D IC make sure you use the DC adapter setting because this IC will then need an external voltage source to drive the motors.