QCX Firmware change request: XON/XOFF flow control for CAT. #qcx #firmware #cat

Sheldon Hartling

Knowing the answer is probably "there's no room" :-) I'll ask anyways ...


It'd be nice to have XON/XOFF implemented for the CAT serial port as an option to facilitate sharing of the IC2 pin 2 and 3 lines.  Currently, in V1.5, a CAT command received by the QCX during an LCD write is ignored.


Before driving IC2 pin 25 high at the start of an LCD write operation, you'd need to send an XOFF character (DC3, 0x13, ctrl-S) to the CAT port.  Then, when the LCD write operation was complete, after restoring IC2 pin 25 low, you'd need to send an XON character (DC1, 0x11, ctrl-Q) to the CAT port.  To be most effective, the XOFF would have to be sent as early as possible during the LCD write operation.  Unlike CTS it takes a little time to work effectively.  The XOFF character has to be sent over the serial line at 38400 baud, received by the computer, decoded, and acted on by the computer's driver software.


Not all computers/applications will support XON/XOFF so this would likely need to be included as a new menu item.


Thanks and 73, Sheldon VE1GPY


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