Flash Magic 3.59.227 can´t communicate

[Andy Ayre]

Flash Magic configures the COM port to disable handshaking, otherwise it wouldn't be able to control DTR and RTS.

Andy

[rbtamd]

It´s ok, but when "Use..." is unchecked there is no reason to use DTR. In this case, Flash Magic must control DTR and leave it asserted to permit max3221 be enabled in the MCB900 circuit.

Roberto

[Andy Ayre]

The MCB900 is designed to use DTR and RTS to control RST and VDD. I would say that any other use w.r.t. ISP entry will require you to modify the circuit because you are no longer using it in the intended way.

Andy

[rbtamd]

Why the difference between the versions? FM 3.50 holds DTR, why 3.59 doesn´t?

Thanks

Roberto

[Andy Ayre]

Version 3.50 lets DTR stay at the default level that Windows sets it to. Version 3.59 explicitly deasserts DTR when the COM port is opened. This is part of a workaround we had to implement to get around a bug in the DTR and RTS handling in the Windows USB COM port driver.

As more and more people are resorting to using USB to RS232 cables it is important that DTR and RTS function correctly, despite a bug in the Windows implementation of the COM port driver used for these cables.

Andy