B&B Electronics Asynchronous to Synchronous Converter 2010 Manuel d'utilisateur télécharger pdf (Page 25)

Department of Computer Science and Electronics

In this section the algorithm of the program is going to be explained. The

resultant C code can be found in Appendix A.

Main function

Call to init_function

While (forever)

Reset watchdog

Do nothing until data have been received and is ready to be read from UDR

Read UDR

If (address=uc’s address or broadcast) do:

If (calibration) do:

Call calibrate function

Call to the function that sends calibration results to EEPROM

Else do:

Call to the function that sends through USART the sensors’ state

End if

End while

Initialize function

Enable watchdog (2seg)

Set microcontroller address

For (8 steps) do:

Read calibration results from EEPROM

Reset watchdog

End for

Initialize PORTB. Pin 2 and 3 as output

Initialize USART. 16MHz and 9600 bps

Initialize ADC. Enable ADC and prescaler 125kHz

Ignore the first conversion of the ADC

Disable transmission

Calibration function

Before illustrating the algorithm, an explanation of how the threshold of a single

sensor is calculated, is taking place.

First of all, as figure 4-10 shows, xprima value is calculated, being the half-sum

of the biggest and the smallest value read during the first half time period of the

calibration. However, this is not the optimal sensor’s threshold, thus in the next half

period of the calibration, a more concrete value is calculated taking advantage of

knowing the value of xprima.

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B&B Electronics Asynchronous to Synchronous Converter 2010 Manuel d'utilisateur Page 25