VMUSIC2 question

[fmr300]

Most of the VMUSIC2 interface schematics show the CTS line tied to ground (signalling the VMUSIC2 that the Stamp is always ready for characters), and RTS not connected (so no way for VMUSIC2 to tell Stamp that it is 'not ready').

I'm ok with the CTS, as the PicAxe can be designed to be always ready for the next char, but what about the RTS line - does anybody know if the VMUSIC2 ever tries to signal 'not ready', and the PicAxe should hold off on sending chars then?

I have seen one snippet of code where the author connects RTS and allows the VMUSIC2 to flow-control the PicAxe transmitter.... but in my own experimentation I've yet to see the VMUSIC2 actually assert the RTS line to throttle the PicAxe, so I hate to add the hardware connection, use up an input on the PicAxe, and add flow-control code in the PicAxe, if the VMUSIC2 never asserts RTS.

Anybody know?

-mark

 

[hippy]

I don't know ... but you could try connecting a LED to RTS or buffering it through some logic if unsure of what current the RTS can source or sink. A LED which flickers on is easier to see than one which blips off. You can wind the R right down to get maximum brightness from the LED with max current through the inverter / buffer.

 

[fmr300]

Good idea - kinda did this but with a scope set to trigger on RTS going high. I did a bunch of commands, including writing a file, and the scope never triggered.

Just not feeling real safe about relying on that experiment.... I asked FTDI tech support and got a somewhat braindead reply.... person trying to be helpful but no knowledge on this topic.