debugging a soundless EMIC-2
Poundy
Posts: 15
Hi folks, first time poster and somewhat not-a-prop-guy, sorry
Got my EMIC2 the other day, sent Down Under, which was not from the "first batch" (ie it was only ordered a few days before the scheduled in-stock day after the first lot ran out). Anyway, all good, it arrived with no visible damage to the box, double bonus.
So here's my dilemma. I have the thing connected to a PC, with a CP2102 USB-serial connector. The EMIC2 comes up, initialises correctly, and I can talk to it using a terminal program (in my case, I am using TeraTerm). I can ask it to say things, I can ask it to play the demos, I can see and set properties correctly; all that works. The LED changes colour as expected (red when busy), and the serial response works as expected (":" returned once finished a command). But what doesn't work, is sound out. I have tried everything, commercial 8ohm speaker (old PC set that still seems to work), home brew speaker on a plug, but nothing seems to give me a sound out. Volume changes across the entire range, again nothing seems to work.
Now I don't know too much about the electronics of a speaker output, and I don't have a heap of tools (no o'scope) to help track down what might be going on, so I am hoping someone can give me some pointers, like watching voltage across a point with a DMM, or some other suggestions. One thing I am trying now (posting this before I try, hoping to also get some other suggestions to try in this diagnostic session) is a more capable input power supply, in case the CP2102 onboard 3v3 can't give enough current to the EMIC2, but I don't even know for sure if the behaviour that I see is reflective of that (Joe?)
here's hoping for some thoughts - thanks in advance !
Got my EMIC2 the other day, sent Down Under, which was not from the "first batch" (ie it was only ordered a few days before the scheduled in-stock day after the first lot ran out). Anyway, all good, it arrived with no visible damage to the box, double bonus.
So here's my dilemma. I have the thing connected to a PC, with a CP2102 USB-serial connector. The EMIC2 comes up, initialises correctly, and I can talk to it using a terminal program (in my case, I am using TeraTerm). I can ask it to say things, I can ask it to play the demos, I can see and set properties correctly; all that works. The LED changes colour as expected (red when busy), and the serial response works as expected (":" returned once finished a command). But what doesn't work, is sound out. I have tried everything, commercial 8ohm speaker (old PC set that still seems to work), home brew speaker on a plug, but nothing seems to give me a sound out. Volume changes across the entire range, again nothing seems to work.
Now I don't know too much about the electronics of a speaker output, and I don't have a heap of tools (no o'scope) to help track down what might be going on, so I am hoping someone can give me some pointers, like watching voltage across a point with a DMM, or some other suggestions. One thing I am trying now (posting this before I try, hoping to also get some other suggestions to try in this diagnostic session) is a more capable input power supply, in case the CP2102 onboard 3v3 can't give enough current to the EMIC2, but I don't even know for sure if the behaviour that I see is reflective of that (Joe?)
here's hoping for some thoughts - thanks in advance !
Comments
The datasheet 30016-Emic2TextToSpeech-v1.1.pdf says
I suspect your voltage is too low. The audio output is only 300mw - try earphones...
First though, have you ever noticed how when you change two things at once, you're invariably going to fix the problem, and then have a 50:50 chance of picking which one was right?
So all my previous tests were with the board connected with .1" header wires straight from my CP2102 to the module and speaker connected via the socket. This time I decided I'd drop the module onto a breadboard so I could firstly supplement the power, and I had a breadboard mountable connector on a speaker so I plugged that in too.
Fire up the terminal and tell it to play the demo. Yep, it worked first time. Bugger. No, no, I mean yay, don't I?
Anyway, so I know this now works - unplug breadboard speaker and whack the plugged one back in, play demo, nada, not a sound. So I undo the power-boost and connect the breadboard speaker again and we're still working.
So, it's the socket on the EMIC-2 board that isn't working. I've looked under a magnifying desklamp and head mounted magnifyer, can't see any obvious solder problems on the three connectors, but they don't have a lot of solder visible - it's still got a small fillet ul the side ofthe leg, so not something I immediately think is worth hitting with the soldering iron. Can anyone confirm what I should see resistance wise between what pads on the socket or some other way to see if I cna figure out if there's a short or something?
Oh, and thanks for the suggestion @Ron. I had run it on 5v and 3v3 before with the same result, and have done so now and both seem to work fine - on my more permanent mounting solution I will make sure I juice it up from the 5v rail though just to be sure.
That means "Not a PC", right?
Interesting to me that it works this way. Not that I'll be trying it, I still find it interesting.
:cool:
So yes, while it may say for embedded systems, this way I could eliminate the "unknowns" of micro controller serial ports etc. Now I know what was going on I'll connect to the micro like intended :thumb:
So again, anyone who has insight into what I can test on the socket would be great !
TRS Wiki here
Check the connections from SP+ to the connector. C38 may be open.
EDIT: SP- does NOT go to the connector.
The SP+ and SP- are differential output from the chip, and per the data sheet that's the normal mode of operation. The jack that Joe implemented should work also.
The Tip and Ring are connected together on the EMIC-2 board, so a mono plug should work just fine.
I would check continuity from the SP+ to C38, and then continuity from the other side of C38 to the Tip or Ring on your mono cable.
BTW, did you try some powered speaker from the jack?
I guess I could check connectivity, but tracking down C38 is virtually impossible, there's no silk marking on the bottom of the board, and it's a 4-layer board at least and all the routing is internal and therefore not visible on the surface under the soldermask.
Edit: tornado warning - wow. Glad to hear things are ok.
Is this a surface mounted socket? If so and you can not get to all pins on it with a soldering iron, maybe reflow with an air soldering tool.
FF
(added above with an edit, had not intended to reply but somehow hit the wrong key. Rather than leaving a blank "Duh??" .......)
However, using one of the button speakers from parallax, wiring sp+ and sp- to the matching pins on the button speaker only produces clicks, but no output of sound.
I thought maybe this was a result of the basic stamp not having enough power left to power the speaker, but since it's powered by a 9-volt battery, this shouldn't be an issue.
I do need to remove power from the emic2 while reprogramming the bs2, apparently the draw on the bs2 from the emic2 is too much to allow the programming to take place, but a simple unplugging of the 5V wire solves the problem.
I'm not sure if the speaker pins (on the emic2) are incorrect or not, no way for me to tell, but if anyone else has tried this configuration (bs2/emic2/button speaker) and gotten it to work, I'd be interested in knowing how it worked out for you.
If anyone has any suggestions on what I can try to make this work, I'd sure appreciate it, I was hoping to use the button speakers, to remove the need for earphone jacks being plugged and unplugged, but perhaps there's just not enough volume for the button speaker to pick up the output.
I had my wife doublecheck the wiring for me before applying power (don't want to toast my shiny new emic2),, and (after changing locations of a couple of wires, off by one row) all was in order, but no sound out of the button speaker, but again, earphones/external speakers work just fine.
Thanks for any suggestions.
If you can get sound out of the socket, but not the SP+/SP- pins, then I actually suspect the speaker is the problem not the EMIC2. Do you have a 3.5mm plug you can solder the wires from the speaker onto, so you can eliminate the pins as the issue? Or an old set of headphones you can cut the wire on and splice&solder the speaker onto?
The SP+/- wire polarity isn't super critical for a speaker to operate. It should still work if you have it reversed, although it likely won't be at an optimal volume. So there is little harm in reversing the connection from your speaker and seeing if that makes a difference to your experience.
My last comment is that 9v batteies are really poor things to use, they don't have a very large current capacity which may be why you see issues, your battery may be sagging below a usable voltage during programming. I'd certainly try to eliminate that too.
Unfortunately, 9-volt battery is the only power I have to use other than the usb port on the board (it's a bs2 homework board usb version) If someone can suggest another way to give it more power, I'm all for trying it out, but afaik, there's nothing else I can feed power into the board with in it's current configuration.
I of course do have a bs2 module (compliments of the mystery bag) so I could move the code to that, but I'm not yet sure how to wire that one up, since I've not delved into it's documentation to see which pins are what.
On the other hand, I do have a quickstart board, but my understanding is that they provide even less power outputs on their vin connection, so I don't think that would help in this case.
Any other suggestions will of course be greatfully accepted.
I was kind of figuring the output power might be too low to drive the speaker in combination with the emic2, but here's a question.
Can I move the power wire over to the vin port on the bs2, and obtain more power output that way? Would that help?
If so, that's a Piezo, not a "real" speaker so isn't going to work.
Would't a short between Tip and Ring render the plug useless? I't only a two conductor plug.
So, if the board you're plugging into (like this one) short Tip and Ring together to make stereo, then a mono plug (where ring and sleeve are the same) will short the output to ground.
thanks everyone for the chat !