Alpine bus protocols

**jics** · 01-26-2006, 04:36 PM

Hi,

Of course it's ia a differntial signal. What you see in the jpgs is the Data+ line.
The coding is RZ, not NRZ, so its no 232,423,422, 485 or CAN. That would be too simple...

The voltage levels (i dont remember the absolute values) are lower than an RS* or CAN line.

Because or the RZ coding it could indeed be possible that the datarate is variable, because the clock could be regenerated by the receiver from the rising edges of the data signal.
What speaks FOR for this theory: You observerd another datarate than I.
What speaks AGAINST this theory: More complicated receiver/transmitter design.

BTW.: Have you found a source for the AI-Net cable connectors (specially the female ones) ?

greetings,

jics

**MartyM** · 01-26-2006, 05:02 PM

Hi, I realized after my last response that you in fact intended to note a diff. bus, but your label threw me off at first.

Note: I only have a few hours worth of experimenting with this so I know my measurements were not finished and I'm probably missing a lot at this point. I can't swear on the data rate until I take some more time with it and measure again (when I figure out why the data capture isn't working everytime).

Here are my ideas based on what you said:
1. Probably not variable data rate
2. I too expect a polling network
3. I wonder if the PIE (or whatever other manufacturer) has a device that can be inspected for more info-didn't PIE or someone else make a Ai-Net compatible adapter?

I had not looked for the connectors yet; that's a good idea. I would like a "break out" cable and much more. I will look into those.

I think I'm going to examine the bus more and come up with another plan.

It kind of ticks me off about the data sheet.

**jics** · 01-27-2006, 01:53 PM

Hi,

3. I wonder if the PIE (or whatever other manufacturer) has a device that can be inspected for more info-didn't PIE or someone else make a Ai-Net compatible adapter?

Something like this would make a (relatively) cheap victim for dissection:
http://www.alpine-usa.com/products/l...h_kca-420i.htm

Who or what is PIE ? I haven't found anything related on google...

regards,

jics

**jbors** · 01-27-2006, 02:03 PM

Interesting topic. I would say that most complicated part in AiNet is not a physical layer, but rather check sum algorithm itself. That's where all other attempts are stopped

**jics** · 01-27-2006, 02:18 PM

HI,

Given the fact that most of the slave devices (e.g.: CD-Changer) have a very limited computing power, it won't be anything more complicated then a CRC-16 with an unusual initialisation vector.
If I have to make a guess: It is a cross-sum modulo X.

...If there is a checksum at all.

regards,
jics.

**MartyM** · 01-27-2006, 02:42 PM

PIE is Precision Interface Electronics, Inc., a manufacturer of OEM and aftermarket stereo component adapters, including some for Alpine units.

I was hoping that might shed some light if standard ICs were used in one of their products, but it was only a passing thought.

**jics** · 01-27-2006, 03:01 PM

From what I see, they don't have any device that communicates over the AI-Net. All cables and adapters just work on the Line L/R cables.
Even the ALP/AI-AUX adapter just switches the Line signals. It's just a better breakout box.

regards,

jics

**jbors** · 01-27-2006, 03:57 PM

Try this: iPod2Car gen2

**jbors** · 01-27-2006, 03:58 PM

Originally Posted by jics

...If there is a checksum at all.

Once you got to that point, post back your findings... I think you may be wrong...

**MartyM** · 01-27-2006, 04:04 PM

Jbors, do you know what setup was being used to monitor the bus values?

I was wondering if someone built an actually working interface circuit or only managed to monitor/capture via test equipment.

Thanks.