Since it's cold and icy outside, I wanted to do some empeg hacking this weekend, specifically, I want to narrow down why I'm getting a *huge* volume spike on my audio overlay patch when my empeg is in the car and the tuner is active.

So to do this, I need some way of seeing debug serial output in the car. I can't get my car close enough to my computer for a serial cable, and I dont have access to a laptop.

What I do have, however, is a Casio Cassiopeia E-100 palm-sized PC running Windows CE. It's got a serial connection on it which ends in a female DB-9 conector. I downloaded a little terminal program for it, and I figured I can use that.

So the docking sled connector has a female end, and so does my WinCE palmtop. So I guess I need a gender changer with 2 male DB-9's. But my question... Do I also need it to cross over? The null modem cable that comes with the empeg is a cross-over null modem cable, but it's got female connections on both ends. Usually having too many females around isn't a problem, but in this case, I've got a bunch of female connectors and no male counterparts. (Write your own joke there.)

Here's what it looks like:

 _____________                       _____________

| Female DB9  |                     | Female DB9  |

| (Palmtop)   |  ---> ????  -->     |(sled serial)|

 \___________/                       \___________/

.
So my question is, when I go to Radio Shack ("You've got questions, we've got ridiculously expensive cables") tomorrow, what do I buy? Just a DB9 gender changer? Two gender changers for each end? I have at my disposal a regular serial cable with male and female ends (non-crossover) and the empeg-supplied null modem crossover cable with the two female ends. What's the least amount of crap I can buy at Radio shack to make this thing work?

So my question is, when I go to Radio Shack ("You've got questions, we've got ridiculously expensive cables") tomorrow, what do I buy?

ROFL, good one.

If it were me, I would buy the necessary parts to assemble my own cable with the necessary male and/or female connectors. This would allow me to use trial-and-error with the TX and RX pins until it worked.

Remember that you only need to connect three pins total: Pin 5, which is ground, and pins 2 and 3 which are RX and TX (and are the ones you swap with trial and error until it works right).

Only way to be sure.

Waitasec, why is it trial and error? Do I *have* to make my own cable? What's so special about the empeg's serial that I can't use off-the-shelf parts?

And the pin numbering is confusing me here. If I'm looking at the sled serial connector (with the row of 5 pins on the top), are pins #1 and #6 on the left side or the right side?

Pins are labeled directly on the connector. In tiny tiny numbers. "Left" and "Right" are arbitrary notions to a connector system that can be either male or female and can be viewed from either side. Always go by the numbers on the connector itself so you can be sure.

Trial and error isn't really needed, no. It's just that I never remember which is which so I just mess with it until it works.

For example:

Connecting PC serial port to empeg main-body-casing serial port: Crossover cable needed.
Connecting PC serial port to empeg docking sled serial port: Straight through cable needed.

I don't know what the port is like on the handheld device you're planning to use. Is its port designed to connect to a host PC? If so, it might be crossed over already and therefore would need the opposite cable of what a PC would need.

So:

Connecting unknown device X to empeg serial port X: ? Cable required?

There's also the issue of... if you're using the docking sled serial port, some of those pins are goofy because they aren't part of the serial spec and you'd probably need to make your own cable anyway, as described here.

No, strictly you don't need to make your own cable, but having the parts handy will ensure that you don't get stuck with a ridiculously expensive pre-made cable you can't use. At least if you have the parts, you only need to swap pins instead of driving back to ratshack to exchange the cable.

Hmm yeah I guess the serial on the palmtop is designed to go to my PC. When I sync stuff to it, I just connect it to the PC with no other cables.

So I guess he's got a crossover. And your'e saying if you connect a PC serial port to the docking sled, you need it to be straight-through. So I guess I have to do ANOTHER crossover just to "uncross" the crossover that's being done on my palmtop's serial cradle? Wow...

Hmm...I've had too many ciders to really work out what has already been said wrt to cross-overs etc, so I'll just add my own input, secure in the knowledge that Tony probably beat me to it

The empeg port is the same as a PC.
The sled port is the opposite.

But don't forget the caveat about the extra signals on the sled port. In particular, pin 4 has 12V on it, which may or may not have some effect on serial comms... so in this respect, making your own cable might be prudent.

Tony, I'm going to throw a wild guess here, and suggest that the overlay patch might need some work done on it to make it truly volboost compatible. Do you have any volboost parameters set?
(This would typically only be seen in tuner/aux modes - although IIRC volboost allows mp3 playback to be boost or cut, I could never see any motivation for doing so - the point of volboost was to allow tuner/aux volumes to be boost/cut to match the mp3 volume, not the other way around, so I doubt anyone would actually set volboost_mp3)

I don't know about how you are testing, but you could try setting ;@AC fake_tuner=1 (check syntax!), and seeing if that helps nay in debugging.

Wow...

Don't feel bad about being confused on this, I am as well. I just got the empeg installed in my new car today, and tossed in the GPS antenna I bought 2 years ago for the empeg (now that it can do something beyond sit on the dash), and managed to get the pins backwards on my cable. I'm tearing the dash apart tomorrow morning to fix it.

Cool, the fake_tuner was helpful in finding the problem. I ended up getting a DB9 gender changer just so I can debug future in-car issues. Seems to be working fine.

The volume spike actually wasn't related to the volume boost stuff. It was my own stupid bug.

I am going to put up a new thread in the Programming forum to discuss the audio overlay thing, I have a few thoughts on how we can do it better. There are some weaknesses in its current incarnation.

If you do much at all with serial connections, you might want to invest in a Smart Cable. Best cable purchase I've ever made.

NOW you tell me!

Blame the power company.

Or old man Winter, I suppose. You guys do know that snow is just frozen precipitation, right?

Nah. Nothing quite beats a proper RS232 breakout box And it's cheaper! Not quite as convienent tho...

- Trevor

I've used breakout boxes for various things, but, assuming that it's really RS232 on either side, the Smart Cable wins each time. The cheaper one fixes most things (that is, swapped TX/RX and swapped DTS/RTS, IIRC) with two toggle switches indicated by two LEDs. It's very simple. A monkey could do it in seconds. The more expensive one can be used to do pretty much anything that you'd reasonably want to do with a breakout box, again, assuming that it's RS232. If you've got some bizarre pinout, though, a breakout box is invaluable.

The description of the Smart Cable's are a bit strange. It all mentions that it's intelligent and that it will analyse the interface but then it tells you to set the switch to what you want??

The Smart Cable is definately still simpler though. A breakout box would need you to know what pins to connect and where. I may see if somebody sells something similar over here in the UK. Annoying having to wander about with a bag of gender changers and adapters.

- Trevor

Basically, there are a few LEDs on it, that just light up when data is passed over certain lines. It then becomes apparent how to toggle the switches in order to get the TX, DX, RTS, and DTS lines lined up. I suppose that their argument for its ``intelligence'' is overstated.