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Add option to send break to RS232 component

Posted: Sun Nov 29, 2015 8:47 pm
by kersing
The current RS232 component does not have a macro to send a break to the output. It would be useful if this feature could be added.

Re: Add option to send break to RS232 component

Posted: Tue Dec 01, 2015 6:57 pm
by Benj
Hi Jac,

Would the break simply output low for a period greater then a byte period? e.g. so the stop bit is not detected.

Re: Add option to send break to RS232 component

Posted: Tue Dec 01, 2015 7:35 pm
by kersing
Benj wrote:Would the break simply output low for a period greater then a byte period? e.g. so the stop bit is not detected.


Yes, to quote from the dsPIC33EP256MU806 datasheet:
UTXBRK: UARTx Transmit Break bit
1 = Sends Sync Break on next transmission – Start bit, followed by twelve ‘0’ bits, followed by Stop bit;
cleared by hardware upon completion


Of course different controllers use different registers/bits so it would be nice if it could be included in the component.

Some Microchip controllers like the 18F2X/45K50 series use break for auto baud or even "Auto-Wake-up on Break" (page 275 of the data sheet). The mechanism relies on the driving controller being able to send the break...

Re: Add option to send break to RS232 component

Posted: Wed Dec 02, 2015 12:07 pm
by Benj
Hi Jac,

Ok so it's something that some chips support in hardware. It certainly looks possible so I'll get it on the list and try and have a go next time I get a min. Should be easy to do with the software mode and would also come in handy for LIN based comms. We currently have an intern working for us on the compiler conversion and the PIC32 chip pack so maybe I could divert him for half a day or so to investigate.

AutoBaud would be another good feature but I would have to think about this one.