So Me and statepkt are doing a Phase Lock Loop evaluation board for the company we co-op at (we're hiring co-ops btw send me your resume again)

I decided that since very few people would understand what a phase lock loop did, that the demo version for design day needed a little something extra...

So I installed a whole bunch of Blue LED's around the perimeter hooked up to GPIO lines on the FPGA... the final version will have an FPGA load that steps through the LEDS clocked by an input signal fed from a frequency generator... So running at ~4hz it'll be kinda slow, then you can speed it up where it starts PWMing the whole thing... "Executive Demo" aka Riced out

11/16/2005 10:17:20 PM

11/16/2005 10:31:20 PM

engineers would whore out their own mother for a flashing LED, i tell you what

11/16/2005 11:23:53 PM

blue nice, BUT CAN YOU ADJUST BRIGHTNESS


do you have to have a local oscillator to match, or no

teach us

[Edited on November 16, 2005 at 11:35 PM. Reason : . i mean resistors and diodes are cool too ]

11/16/2005 11:33:15 PM

PWM will adjust the brightness Padawan, you must believe in the force and use it wisely

its a full PLL, there is a local 155Mhz high precision VCXO (yes oscillator) it is phase aligned (with a standard offset to avoid deadzone effects) to an input signal. that was the actually design

however, with the functionality available on the board, I can take the reference signal (variable) and devide it down to nothing (I.e audio range) and then percieved brightness of the LED's will vary according to speed, all the way down to being able to see them chase each other

[Edited on November 16, 2005 at 11:39 PM. Reason : PLL = Phase Detecor + Charge Pump + Loop bandwidth filter + VCXO + feedback ]

11/16/2005 11:36:14 PM

flicker brightness adjustment?

^thanks for the update, nice

[Edited on November 16, 2005 at 11:42 PM. Reason : .]

11/16/2005 11:42:22 PM

yup... although I did actually write a module to do true PWM on each LED before moving to the next one... this would cause each one to "glow" before stepping to the next one... not sure if I'll have time to fully characterize it before design day... the filcker adjust is quick dirty and easy

11/16/2005 11:45:10 PM

^

yeah, it gets the job did.

triac of doom

i think i get asked every single month why you cant use a 120vAC dimmer switch on a fan with a full linear adjustment range >.<

11/16/2005 11:47:50 PM

did I mention that was a controlled impedance board

but once again that goes back to... normal people don't understand that took 1337 design for the high speed terminations including burried capacitance and a faraday cage style design

so they will smile and goo at the flashing blue LEDs

11/16/2005 11:55:47 PM

hey Dumbass, i'm curious how you soldered that main chip in the center of your board - it looks like its got those tiny surface mount pins.... if so, did you get someone else to solder it?

11/17/2005 9:54:30 AM

Its easy to do.

11/17/2005 9:57:45 AM

I don't understand half the jargon in this thread.

11/17/2005 11:04:10 AM

The board was built production style... too many components to put on in the time frame we had... however, we did put that chip on in house, there is a machine that does it... however we do from time to time have to lift pins for debug purposes that are that small, its not difficult to do with the proper equipment (metcal soldering iron, wellers wouldn't stand a chance, and a razor knife). I've put on 20pin chips that had smaller leads than that numerous times when I was working on the last main board project... (I kept blowing them up and having to replace the same chip :beatup

11/17/2005 11:09:22 AM

^ cool that's what I was thinking... do you have a microscope?

who'd you have install your components? we ended up having to go with a company out in Garner due to time constraints

[Edited on November 17, 2005 at 11:25 AM. Reason : s]

11/17/2005 11:24:03 AM

What is the technical name for the LEDs you used? They don't appear to be the standard 5mm, but more like the basically flat ones (I obviously don't know what they are called beyond "LED").

If they are 5mms, then what kind of LED is used in a cell phone for instance?

[Edited on November 17, 2005 at 8:55 PM. Reason : clarity]

11/17/2005 8:52:45 PM

^ surface mount, SMT ?

11/17/2005 10:55:12 PM

standard 0603 SMT package...

the fucking PLL won't lock... I spent 12 hours on it today... however the blue LED's dance happily around the board...

11/17/2005 11:56:30 PM