Propeller Problems (Xtal and serial libraries)
Agent Cobalt
Posts: 88
After receiving my propeller and USB2SER, I went to the local electronics store to pick up a crystal and some other parts. I know it needed to be 2 pin and anywhere from 4-80MHz. Now all I have to do is just put it across pins 30 and 31, right? If so, I did that and when I compiled and ran my code, the propeller wouldn't run. Are there any certain other specifications as to what the crystal should be?
Second, I've been working on prototyping a design on the propeller and can't seem to get the serial libraries (simple and full duplex) to work right. I specified the parameters necessary, but the propeller doesn't seem to output any data on the out pin I specified. Is there some information on how to properly use the libraries because I'm thinking I have done something wrong.
Any help is appreciated. Thank you.
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Truth can be dangerous... Trust can be deadly.
Second, I've been working on prototyping a design on the propeller and can't seem to get the serial libraries (simple and full duplex) to work right. I specified the parameters necessary, but the propeller doesn't seem to output any data on the out pin I specified. Is there some information on how to properly use the libraries because I'm thinking I have done something wrong.
Any help is appreciated. Thank you.
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Truth can be dangerous... Trust can be deadly.
Comments
(it has a RC-clock built-in that it runs on until you specify something else )
Anyway, what's the specification on the crystal?
If it is more than 10MHz, DO NOT enable the PLL as it multiplies the xtal frequency with 16, and 160MHz is the max before the PLL fails. (this happens whether or not you actually USE the 16x output of the PLL, as it ALWAYS multiplies with 16, and just varies which 'tap' it takes the output from)
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Truth can be dangerous... Trust can be deadly.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Truth can be dangerous... Trust can be deadly.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I've wired the propeller up just as shown in the manual I downloaded.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
· _CLKMODE· = XTAL1 +·PLL16X
· _XINFREQ· = 4_000_000
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Jon Williams
Applications Engineer, Parallax
the proper timebase for the specified Baud.
With that said, you shouldn't be able to downlaod the code to the Propeller due to the following message...
...So I'm a little confused as to how the LED is "ON" at all.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Post Edited (Beau Schwabe (Parallax)) : 5/13/2006 4:37:12 AM GMT
Jon's suggestion as far as specifying the crystal should work.
Below is more of an FYI:
This method is not extremely accurate, but it would be comparable to the RC time.
The difference is that you can use the PLL options as well as '_CLKFREQ or _XINFREQ'.
Simply use a 10uH coil in place of where you would put a crystal.
In code, specify using a xtal3 so that the internal 16pF capacitor is selected.
The frequency comes out to be about 12.6MHz, so specify this for your '_xinfrequency' value.
F = [noparse][[/noparse] 1 / (2 * pi) ] * sqrt [noparse][[/noparse] 1 / (L * C) ]
Now, as I said, this isn't extremely accurate so don't expect to be able to use high speed baud rates with this method.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Post Edited (Beau Schwabe (Parallax)) : 5/13/2006 5:49:35 AM GMT
And you must not run the PLL for crystals over 10Mhz as the speed limit is 160Mhz?
Above that, things get funky.
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-Phil
One thing I've always had as a habit when working with such boards is to have the GND at the bottom and Vin at the top.
I find it much easier to spot errors then, as schematics are also drawn that way.
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Truth can be dangerous... Trust can be deadly.
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Not to look past the obvious, you are changing the code that specifies rc or crystal aren't you?
or
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
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Truth can be dangerous... Trust can be deadly.
"I'm leaving!"
"But I haven't set you on fire yet!"
Post Edited (Agent Cobalt) : 5/14/2006 2:18:02 AM GMT