Serial port echo on boot confuses the poor empeg

Posted by: Shonky

Serial port echo on boot confuses the poor empeg - 21/12/2004 05:47

For those who haven't seen the thread about emulating a CD changer in an empeg, I have the majority of mine working.

However, due to the inherent 1-wire nature of the BMW ibus, the empeg sees everything it transmits. This is no problem for my code, since I ignore stuff not sent to the CD changer address (and thus what I send).

However all the stuff that spews out when the empeg is booting gets echoed back into the serial port. This seems to seriously confuse the poor empeg though. Particularly when it echoes the echoed character and a vicious circle ensues. I haven't actually captured the port yet, but I can guess it's not very nice.

Ideas currently are:
1) special hardware controlled by a serial port control line
2) connect to one of the other serial ports (IrDA or tuner)
3) reprogram kernel to swap serial port and tuner/IrDA.

I only thought of 3) while writing and it seems pretty good and probably quite simple to do as well. Any other suggestions?

Thanks
Posted by: tfabris

Re: Serial port echo on boot confuses the poor empeg - 21/12/2004 14:36

4) Time-delayed relay not connecting the wire for about 15 seconds after power-on.

I even solicited the BBS's help in creating just such a circuit to mute my radar detector during its POST.
Posted by: Shonky

Re: Serial port echo on boot confuses the poor empeg - 21/12/2004 22:08

Creating a delay circuit would work except if I ever rebooted (rarely). However it seems to be working fine now. Don't know why...

I have button presses figured out so I can drive the empeg including menus from the main head unit (still need to see the empeg though).

Now I just have to figure out how I'm going to mount the thing and sort out some sort of remote display (sharing the same comport ughh).
Posted by: DJZorro

Re: Serial port echo on boot confuses the poor empeg - 22/12/2004 20:20

Hey Shonky, use "our" other BMWish thread for these questions
Anyway, to resolve this thing, just:

1) Patch the kernel in order to return(0) on printk (also remove gunzip Loading........... stuff),
2) cd /dev; rm console; ln -s ttyS2 console

If you need anything (kernel, I-BUS emulor) without waiting for my web site update, just drop a message: I can send you my stuff (even if a bit dirty) that already works good .
Posted by: Shonky

Re: Serial port echo on boot confuses the poor empeg - 22/12/2004 21:48

I figured it was a sort of generic question and I didn't want to hijack yours any more.

Anyway it seems to be working fine now. The empeg doesn't seem to care about the echo anymore and I have the empeg booting up and running my program automatically. Main problem is that now the radio keeps forgetting it has CD changer so I have to wait for the broadcast. The radio doesn't seem to understand the announce message.

I already have done my Ibus code now so I won't need yours but thanks anyway. When you get yours up it might be worth comparing to see what each other did.