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| Synchronous RS232 communication. |
 Posted: Wed Dec 22, 2004 6:15 am |
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Hello,
Why doesn't the CCS compiler support syncrhounos transmission, like half-duplex?
Greetings
Joris |
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Ttelmah
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| Re: Synchronous RS232 communication. |
| Posted: Wed Dec 22, 2004 10:00 am |
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| Anonymous wrote: | Hello,
Why doesn't the CCS compiler support syncrhounos transmission, like half-duplex?
Greetings
Joris |
Half duplex, and synchronous, are two very different things. Half duplex, purely implies that communcation is only in one direction at a time, and is commonly used on interfaces like RS485, with just one 'set' of signal wires, and only down to handling the timings of the transmission, and the control of the data direction pins on the transceivers, to reverse the bus direction as needed. Synchronous, can be either full duplex, or half duplex, but the USART in the PIC, only supports half-duplex. You can use the normal serial code in CCS, to drive, or receive from a half-duplex synchronous bus, using the USART, all you have to do, is manually set the 'SYNC' bit of the USART, and the CSRC bit to control the direction. Again, since this is a half-duplex mode, you need to control the direction control lines for the transceiver. remember also that you have a seperate synchronous bus available in the SPI, and depending on the nature of the other devices connected, this may be the 'better' peripheral to use. This allows duplex transmission/reception.
Best Wishes |
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LytseFlap
Joined: 22 Dec 2004
Posts: 6
Location: Leeuwarden
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| Posted: Fri Dec 24, 2004 2:46 am |
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Guest is me.
The syncrhonous communication is als used for communication between microcontrollers. In this case with a joystick/power module of a wheelchair from Penny & Giles' Pillot+ system. In this case syncrhonous transmission is possible for RS232.
There's one difference betwee synchronous an asynchronous. The values of the stopbit and startbit are inverted!
And I'm very decadent. I use the CCS compiler to make quick a solution and polish the code up with registers and sometime assembley (in case of low memory, putc() easily puts a value three time on a stack). So in this case it was time saving for me that the CCS-C code could setup a Odd-parity synchronous transmission for me.
A real engineer never spoils time, but learns from it. ;) |
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