B&B Electronics Asynchronous to Synchronous Converter 2010 Manual do Utilizador descarregar pdf (Página 30)

Department of Computer Science and Electronics

that one uses the latest Win AVR release (after 2007-01-02). However, the either

analogue or UDR register simulation has not yet been supported, and that was not

sufficient to ensure the correct operation of the code.

Urged by the need to communicate and send the sensors’ state, Atmega16 offers

the USART or the SPI serial communication. But normally the SPI bus is used for very

short distance communication with peripherals or other microcontrollers that are located

on the same circuit board. This is different from the UART, which is used for

communication over longer distances, such as between units or between microcontroller

and PC. The SPI was developed to provide relatively high-speed, short distance

communication using a minimum number of microcontroller pins. That is why the

USART was chosen. [6]

4.3. Solution

The schematic, the layout and the code can be found in the appendices. The time

spent in this project was enough to make the program work as expected, thus the

purpose of this thesis has been almost achieved. Nevertheless, much more things could

have been achieved in a longer period of time, as the use of the microcontroller provides

us with certain abilities.

It seems that all things mentioned above are working as they were expected. The

report focuses on one single board, although the author’s strongest aim was to make 3

cards and the PPC work in the same network. Given that a correct performance in the

system consisted of the PC and the simulation kit has been verified by tests, the entire

network is highly likely to work.

5. Results, analysis of results, recommendations, future

work

As the STK500 responds right to the PC orders, it is verified that, at least, the

code is correct.

The code mainly includes a while loop which, depending on what data it

receives from USART, will call the respective function. It is also evident that the non-

interrupts provided by Atmega16, are not used. The reason is that the microcontroller

has no other task to perform; therefore there is nothing wrong in waiting an order. For

this specific application, the interrupts are not potentially useful. However, both ADC

and USART are somewhat slower than the processor; thus, the latter waits for each

analogue conversion or USART data transmission, and this results in a waste of time in

some occasions. The use of interrupt-driven mode, nevertheless, would solve this

problem.

The reason for choosing the single ADC mode is that this was the most suitable

one for this application.

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