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Rockbox mail archiveSubject: Re: Still Problems with AJB RemoteRe: Still Problems with AJB Remote
From: sophana <jobarjo78_at_yahoo.fr>
Date: Fri, 16 Jul 2004 14:31:17 +0200 [IDC]Dragon wrote: >>Sophana told me once to simply use a 10k resistor and connect it directly >>from my uC's UART pin to the JB's remote pin. >> >> > >I can't recommend that, because it weakens your ability to pull the pin low. >The Archos has an internal pull-up on the remote input, which I have seen >being either 1 kOhm or 10 kOhm. >If you use the pin just as an input (not bi-directional), I'd recommend to >use a schottky diode to "emulate" an open collector. The diode will allow >your Atmel to pull the pin low, current flowing out of the remote pin. But >it will prevent your Atmel from driving it high up to the 5V level. Instead, >the internal pullup will take care of the signal going up again. > > > Hmm, I didn't know there were an internal pull up. In this case you are right, the low offset (schottky) diode is the best solution. (although I don't know a wide schootky diode reference like 1n4148) If you don't have a schottky, a 1n4148 could work but you will be near the voltage limit. >>Does anybody know, what are the differences of the remote input circuit >>inside the Studio Player's, old Recorder's and newer Recorder's (like V2) >>? >> >> > >Thare should be none, except for the strenght of the pullup. > > > >>Maybe anybody has a schematic ? >> >> > >See the ducumentation pages. > > > >>Does anybody know a universal circuit to drive the remote pin, that works >>with ALL models ? >> >> > >The universal bidirectional solution is that circuit with a MOSFET >inbetween, preventing the voltage to rise above 3.3V. I once posted that, am >too lazy to dig it out right now. > > > the mosfet will not do the open collector behaviour. It is indeed usefull for adapting the voltage for a bidir pin. But his uart Tx pin is not bidir. >Jörg > > > _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2004-07-16 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |