sx48 go to sleep
stef
Posts: 173
Hi
I have been working on one off my projects. I created first on a testboard with some hardware my setup. I made my program in sx/B and after some succesful test I made my own circuit bord. I downloaded the same program as I used on my testboard· and everything is working fine. At that point I have still the sxkey connected and generating the clock (50MHz). When I now disconnect the sxkey and insert the resonator (50MHz) the program is running for about 20sec and then stops running. I also see that when I 'm running on the sxkey the whole curcuit is consuming +/- 100 mA. That is normal by my calculation. On the resonator I see that during the first 20 sec it is the same 100 mA. But then it is dropping to 40 mA.It seems like the sx48 is going to sleep but I did not program/want it. It is not going to sleep on the sxkey. If I give hime a reset It is back running for 20 sec.
I don't understand wy it is working with the sxkey and not with the resonator.
Some info
I use an sx48.
Program in sx/B
resonator 50MHz.
Has someone a clue to what can cause this problem??
Thanks in advace
Stef
I have been working on one off my projects. I created first on a testboard with some hardware my setup. I made my program in sx/B and after some succesful test I made my own circuit bord. I downloaded the same program as I used on my testboard· and everything is working fine. At that point I have still the sxkey connected and generating the clock (50MHz). When I now disconnect the sxkey and insert the resonator (50MHz) the program is running for about 20sec and then stops running. I also see that when I 'm running on the sxkey the whole curcuit is consuming +/- 100 mA. That is normal by my calculation. On the resonator I see that during the first 20 sec it is the same 100 mA. But then it is dropping to 40 mA.It seems like the sx48 is going to sleep but I did not program/want it. It is not going to sleep on the sxkey. If I give hime a reset It is back running for 20 sec.
I don't understand wy it is working with the sxkey and not with the resonator.
Some info
I use an sx48.
Program in sx/B
resonator 50MHz.
Has someone a clue to what can cause this problem??
Thanks in advace
Stef
Comments
I also hear some tikking at the moment the programe stops. Don't know if it is importand. I hear it not when sx48 is running on sxkey. It is comming from the sx48 because when I power the circuit without the sx on it I never hear it.
stef
If you are using OSCHS3, try using OSCHS2.
Bean.
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I tried what you sugested but with no changes. The program is stil running for some seconds on the resonator but eventualie it stops. On the sxkey I left it running for more than an hour without any problem.
Can you think of something else ???
I attached the sx/b code if it helps. I don't know if thier are error's in it. I'm juist a beginner.
·stef
Does the SX48 get really hot before it shuts down ?
Is this on the SX-Tech board ? Or is it on your own PCB ?
Bean.
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No i did not try OSCHS1. I will try it this evening. What is the diffrence between the tree settings??
No the sx48 is not getting hot. It stays normal in all conditions.
It is on my pcb.
Il keep you informed of my test.
Stef
Sorry it took me so long to answer but I hade a raod show to do for my company that took a lot off my time.
I also tried now OSCHS1 with the result that also that nothing changed.
Is thier some other things I can do. I realy need the sx48 up and running.
Stef
Did you tried a different 50MHz resonator ?
Have you tried a different SX48 ?
Do you have bypass caps at the SX48 ?
Can you post a schematic of your board ?
Bean
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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I already have some answers to the questions.
1) Yes I have a 10K to vdd from MCLR. Thier is also a NO contakt from MCLR to GND. I use it as reset kontakt.
2) Yes I tried already several diferent resonators. same result on all.
3) Yes I tried divrent SX48. same result on all.
4) What do you mean with bypass caps. I have an 0.1µF cap betwien vdd end gnd close to the sx48. I do that with all my projects and ic. Is that what you mean with bypass cap. Else please explain.
5) I have my hand draw schematic. I 'm going to scan that so I can post it. Give me some time because I don't have a scanner. I get it to you as soon as possible.
stef
In attachement you can find two scans of my schematics. I hope you understand my drawings.
I made a smale supprint with only the sx48 on. You can find de pin numbering in img2. That print I can plug on the main print (img1). This way I can swap sx48 without much soldingwork.
One thing I'm not shure off. Thier are several pins gnd and vdd on the sx48 ship. (see ex pin 1,7,21,35 for vdd) I made for all the connection to my power supplie. Same for gnd. Is that necassery??? Is that casing the problem?? I don't know.
Can you give mee a look at the schematic and give me your findings/remaks ....
Thanks in advance.
Stef
Stef
It is good and in some cases necessary to connect all of the VDD and GND connections. They are especially helpful in allowing the chip to conduct its full current capabilities as tiny wires and connections are able to handle less current. The multiple connections help overcome this effect.
As for the problem you described, can you run a simple test program on the same circuit without experiencing this problem? It can be any simple program that is easy to tell if it is still running or not such as flashing an LED or toggling an output. The purpose is to try to determine if this is strictly a hardware problem you are experiencing that will affect every program you run or if it seems to be dependant upon something in the DTMF software you are using.
I hope this is helpful.
- Sparks
It is a bit hard to read the schematic but I was wondering what you've done with the RTCC pin on the SX48 chip. Did you leave it unconnected? If so you should connect it to something or at least tie it high or low.
Can you try a different resonator? I just ran into an odd problem this weekend while using one of my SX48 DIP modules and it ended up being a bad resonator. Once I swapped it my program started working fine again. I confirmed that the resonator was the problem by trying it on another module. This is the first time i've ever run into a bad one but it is worth checking. If you look at some of the schematics out there that use the SX48 w/resonator you may notice that some add a small ~ 5pf cap on one side of the resonator. Depending upon how you laid out your board you may have to try adding a cap like this. You should also try adding a small cap .1mf across the supply lines right at the SX48 chip.
Another thing that you would want to try is a 50Mhz oscilator instead of the resonator. One important thing to note if you do this is make sure the oscilator is in a socket so you can remove it for programming!! It can not be in the circuit like a resonator can.
Good Luck,
Robert
Thanks for all the help. First off all I left the RTCC open (unconected). How do I correct this problem? Do I connect it to 0V or to 5V?? Does it need a resistor? I never use the RTCC. If I connect it do I also need software added for that (I'm using sx/b) even if I 'm not wanting to do something with it.
Second, I already tried a diferend resonator. With the same result. So I can exclude that option for the mallfunctioning resonator. The 5pf cap. Can you explain a bit more of that? How to connect exactly and what has it as purpose?
The 0.1 mf caps across the supply al already thier. I always do that.
I already tried a lot. Different sx48, resonators, programs and power supply's. It is giving me always the same reaktion. Tomorrow I'm going to recheck everything. Perhaps I oversaw something. Is thier something I can see swith a scoop to check. Perhaps on the resonator pins??? What choud I expect to see?
stef
I usually just tie the RTCC pin to gound on my projects. An easy way to do it is just create a small solder bridge from the RTCC pin to the groud pin next to it. This is what I normally do on my SX48 DIP module:
http://forums.parallax.com/showthread.php?p=627108
In regards to the resonator it may not be the problem since you've tried another with the same results. On the other hand if you've tried the exact same brand perhaps it is something odd with that and perhaps a different brand of resonator might give better results.
When using the resonator besides a small cap there is often a 10K resistor used as well. You can clearly see this as it is used on the Parallax BS2p40 Stamp module:
www.parallax.com/dl/docs/prod/schem/BS2p40SchematicRevD.pdf
What board do you have the SX48 chip mounted on? Is the Parallax SX48 Protoboard or some board that you designed? If it is your board is it one that you've etched yourself or one that you designed and had fabricated? The layout of the traces can adversely effect performance and cause erratic behavior. Is the resonator close to the CPU? Speeds like 4Mhz are far more forgiving than 50Mhz. The faster you go the more critical the board layout becomes. At high speeds you need to start thinking more along the lines of RF and analog design than purely digital.
Just a few things to consider.
Robert
Thanks for the advice. Problem is solved by ading th 5pf and the 10K like you sugested. I still not sure wy this solved the problem an because I 'm a technichan I always want to know wy. I never had this problem in my previus designs. Still it is solved now and I thank you all for this nice forum and information.
stef