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From: e109282 on 13 Sep 2005 10:57
Hi,

This is an interesting issue considering the serial port communication
applications in Atmel AVR Processors.

I am using currently Procyon AVRlib C-Language Function Library for
Atmel AVR Processors to write application over Atmel Mega2560.

The library has Dual UART driver with buffer support. ( uart.c / uart.h
) files. We can set the speed of the port. Good J When a new data is
received, it receives a hardware rx interrupt and the interrupt routine
puts the new data in buffer. Right. Up to this point, there is no
problem.

What if we have a protocol that uses 1 start bit , 8 data bits , 1 stop
bit and even parity ? This makes it difficult to imagine in byte
structured buffers used in the library. Does this library handle the
start, stop and parity bits, I didn't come up with these.

So, the only option is to write extra routines into the library. But
can anyone give me information about the followings :

1 ) Does Procyon AVRlib handle the start, stop and parity bits of the
serial communication protocol ?

2 ) If not, what will we have in the buffer (lets say, buffer size is
10 bytes) after receiving a data stream like this :

1 st Data Byte : StartBit - DATA - Parity Bit - StopBit
1 - 10101010 - 1 - 0
2 nd Data Byte : 1 - 10101010 - 1 - 0

3 rd Data Byte : 1 - 10101010 - 1 - 0

Will the the last bits of the 1 st data byte go into the 2 nd byte of
the buffer? If so, do the first couple of bits go into the last bit
portions of 2 nd byte of the buffer ? And so on...


Or should I implement the protocol handling in the rx / tx hardware
interrupts?

Anyone got the idea?

B. Erbil KONUK

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