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Rockbox mail archiveSubject: Re: ANNOUNCE: Rockbox emulates M-Bus car CD changer (Alpine and OEM)Re: ANNOUNCE: Rockbox emulates M-Bus car CD changer (Alpine and OEM)
From: [IDC]Dragon <idc-dragon_at_gmx.de>
Date: Fri, 13 Feb 2004 18:05:17 +0100 (MET) > If I understood correctly, there is a PIO connected to the remote pin. Yes. > I dont know if it is possible in the archos, but it might be possible to > trigger an interrupt at each transition. No, unfortunately the pin is not interrupt-capable. And this is where the nice general concept collapses, sorry. Under some circumstances it is possible to abuse the UART RX feature to have an interrupt, like I do. RX waitts for a start condition (falling edge), then with the set baudrate captures the start bit which must be low, some data bits and optional parity, then the stop bit which must be high again. Is any of the "must" is violated, it generates a framing error. For my Alpine protocol this is usable, I can set the baudrate in a way that start and stop condition are always fulfilled, but not in general. Dirk-Andreas did the IR like this: a) set RX to highest baudrate, so that it generates RX or error interrupt if anything moves b) if above comes, enable a high-speed "polling" timer interrupt for a while, to sample the remote pin > When the high level protocol decides to transmit data, it just disable the > interrupt for the input and then it can drive the remote pin. > This technique of setting the interrupt handler for each transition is > used > in the universal infrared receiver design. I think that it is generic > enough > to provide a general purpose remote control api. For IR, yes. But I'm not following as far as generalizing CD changer protocols, serial keyboards, etc. into that as well. Each should have it's own low-level driver. > I've read about the sony s-link, which seems very similar to the M bus > encoding (pulses to encode 0 and 1) it is also compatible with this > generic technique. > > The sony S-link seems more interesting to me because sony pilot changer > are > cheap and widespread. The protocol is also well documented. It is even > possible to display song names. I like that, but happen to have an Alpine. Jörg -- GMX ProMail (250 MB Mailbox, 50 FreeSMS, Virenschutz, 2,99 EUR/Monat...) jetzt 3 Monate GRATIS + 3x DER SPIEGEL +++ http://www.gmx.net/derspiegel +++ _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockboxReceived on 2004-02-13 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |