From: [IDC]Dragon <idc-dragon_at_gmx.de>
Date: Thu, 1 Apr 2004 13:43:32 +0200 (MEST)

> >Did you succeed to do IBUS directly, or are you communicating to an
> external
> >controller via RS232?
> >
>
> Someone designed a bidirectional level shifter using just normal NPN
> transistors and resistors. I can send you the schematic if you like.

Yes please, sounds like something worth keeping.

> This
> interface is capable of sinking all the current needed to bring the car
> bus
> down to around 0V. We are still facing some reception/transmission errors
> when the radio volume is loud. It is strange but the louder the volume the
> more errors we get in the comunication. However, interfacing a notebook
> with
> an RS232-IBUS interface gives us no problems. No reception errors. But we
> can also see some transmission errors coming from the archos. So, if the
> radio volume is low enough everything is ok. If we turn the volume up, the
> archos starts seeing lots of parity errors. And sometimes it also fails to
> transmit...
> I don't have a scope but Richard (the person that designed the circuit)
> will
> probably take a look at this issue during the weekend.

A scope should be able to solve that mystery.

> I tried to modify the archos to have a full duplex uart but I faced a very
> strange situation. I wired the wires to the line-in plug but I started
> having noise in the comunication. I tested this at the simulated bus at
> home
> and I couldn't make the trasmission to the archos reliable. Would I need
> to
> cut the traces from the line-in plug to the audio input pins on the mixer
> chip?

Yes, better do that. I've put resistors inbetween, so I have some residual
line-in functionality for test purposes.

> The wires passed quite near some coils inside the archos. Could this
> be the problem?

I don't think so.

> >My Alpine interfacing is not intelligent, because I abandoned the
> external
> >microcontroller approach. The AJB has to do the interfacing, protocol and
> CD
> >changer emulation in an own module, the benefit is that I don't need
> external
> >hardware. But despite this, it will also be useful to have a common
> internal
> >API for remote commands, I'd be just bypassing the RS232 command parser
> part.
> >
>
> That's right, the rockbox code could provide that super remote control API
> and all that our emulators/gateways would need to do was to handle
> input/output and protocol translation... Perhaps it could even be in the
> form of a loadable plugin...

My far-away dream, too. For the time being, I'd be more than happy if we
have an internal control API. This could then be used by the Archos remote code,
or a BMW/Alpine module, or the RS232 command processor for external
controller boxes. Selectable at compile time which module to bring in.

> >Yes, I'm interested.
> >
>
> Do you want it right now (it's full of ugly test code) ? If yes, please
> let me know where to send it...

Just send it to this address.

Jörg

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Received on 2004-04-01