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Need help on getting 10Mhz crystal to work. — Parallax Forums

Need help on getting 10Mhz crystal to work.

MahonroyMahonroy Posts: 175
edited 2015-01-26 12:56 in Propeller 1
Hi guys,
I am using this 10Mhz crystal:
http://www.mouser.com/ProductDetail/ABRACON/ABM3C-10000MHZ-D4Y-T/?qs=%2fha2pyFaduiXg%252bfADAvCicUyned7xDoAWF9kjnvkw7SlDe4TrsZHtg%3d%3d
Part number: ABM3C-10.000MHZ-D4Y-T

From reading on these forums, it looks like I could just set these 2 constant variables and I should be good to go:
_clkmode = xtal1 + pll8x
_xinfreq = 10_000_000

I tested it using the Parallax Serial Terminal, and I get a screen full of random characters on the terminal. (and the program does not work). I swapped the crystal out for the original 5Mhz version, changed the constant variables back, and it works perfectly. So it seems that I either don't have the settings correct, or it seems that maybe I have an incorrect pinout for this part? What do you guys think?

By the way, I was having a hard time figuring out which pad is what based on the datasheet. The datasheet shows that pin 2 has a little angle on the pad to indicate that its pin 2. If this is the case, then the "top view" of the crystal is incorrect. Assuming that the indent pad is pin 2 (which is ground), and the opposite pad is pin 4 (also ground), I just used the other 2 pins for the crystal connection.

Thanks and any help is greatly appreciated!

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2015-01-26 11:28
    Typically, the "angled" corner will correspond to pin 1. Also, with the nomenclature reading right-side up, left-to-right, pin 1 will usually be in the lower left-hand corner.

    -Phil
  • LeonLeon Posts: 7,620
    edited 2015-01-26 11:33
    Use a DVM to find the two ground pads (they will be joined). The other two pads must be the crystal connections.
  • DomanikDomanik Posts: 233
    edited 2015-01-26 12:04
    The datasheet drawing takes some getting used to. The photo helps. Pin 1 has the angled pad cut and pin 3 is diagonal from it. Once the land pattern has the ground pins (2 & 4) diagonal from each other, it should work even if it's soldered in backwards. This makes me wonder if it was working (random characters were displayed) and the serial settings were off just a little bit. Seems like if an LED blinking at one second intervals (30 times in 30 seconds) it must be running at the right frequency.
  • MahonroyMahonroy Posts: 175
    edited 2015-01-26 12:29
    Thanks for the help guys. Sure enough after I took a voltmeter to this thing, the pad with the angle on it is pin1 (so the datasheet is completely wrong then?).... the datasheet shows from multiple diagrams that the angled pad is pin 2.
    I soldered this thing in with the changes and it works perfectly.
  • DomanikDomanik Posts: 233
    edited 2015-01-26 12:56
    Mahonroy wrote: »
    so the datasheet is completely wrong then?
    Yes, both top and bottom drawings are wrong.
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