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Cross-posting from the 8052.com forum http://www.8052.com/forum/index.phtml A while back (http://www.8052.com/forum/read.phtml?id=23083), I asked about how to get a PC to read the 9th bit in Mode 2/3: Multiprocessor Serial bus format. I need to be able to detect the state of the 9th bit for each received byte. Mahmood Elnasser suggested the cport library: http://www2.arnes.si/~sopecrni/downloads/CPort263.zip I've downloaded this, and it doesn't look like it'll do the job :-( (It looks like it'll have the same problem as AsyncPro) The OnRxChar Event could return any number of characters, but the LastErrors Method - as its name suggests - only tells me what the last error was; ie, I can't tell which of the received bytes had the 9th bit set (Parity error). Any help would be greatly appreciated. I'm currently looking around at direct IO drivers for Windows (yes, I know it'd be a doddle in MS-DOS).
"I'm using the ComPort component in BCB from Dejan Crnila," Yes, that's the one I mentioned above. As I said, from the description in the Help file, in sounds like it's no good. "it includes the full source code." Yes, the source code is included, but it's not documented! :-( A quick look at CPort.pas shows that it relies upon the Win32 API - using CreateFile, etc Therefore it is doomed - the problems mentioned are inherent in the Win32 API. :-(
With multiprocessor serial bus configuration of 8052, I understand that one-to-many communication is possible (like a tree).
Master <--+------> Slave 1 | +------> Slave 2 : : +------> Slave N
"It is impossible to make a many-to-many communication with this mechanism" (my emphasis) Yes, that's right, because there is no way to stop multiple devices writing to the bus at the same time & corrupting each other's data; By have 1 Master and many slaves, the Master ensures that only 1 slave may transmit at a time, and collisions are avoided.