P1 Hardware Vrs P1 FPGA - Oscillscope Outputs >>> Frequency Synthesizer demo v1

Bob Lawrence (VE1RLL)

Which Oscillscope output is the hardware version of the P1 chip and which output is the FPGA version?


(Just a quick test but nothing scientific or calibrated.)

Test program:


{{
*****************************************
* Frequency Synthesizer demo v1.1 *

* Author: Beau Schwabe *
* Copyright (c) 2007 Parallax *
* See end of file for terms of use. *
*****************************************
Original Author: Chip Gracey
Modified by Beau Schwabe
*****************************************



Pictures 1( RED)
Scope Output on pin 0
Scope Output: Measurements on pin 0

Pictures 2 (Yellow)
Scope Output on pin 0
Scope Output: Measurements on pin 0




I ran out of time for tonight because I had problems getting the USB driver for the scope to work. Then I upgraded the Firmware. However, when I did the firmware upgrade it reset all of the menus and text to Chinese. I suddenly realized that my Chinese is no good at all.That took about 20 minutes of stumbling around to change it back to English. LOL

Cluso99

Nice work Bob.

I was going to say yellow (real P1) because the P1 is built from slower silicon. But then thinking further, the P1 has better drive capability and therefore should stabilise quicker, and hence would point to the red.
So now I have no idea.

T Chap

I say that P1 is yellow.

Tubular

I think P1V (FPGA) is Red

pik33

Seems to be yellow for FPGA. Every period of this square wave is different.
FPGA version has no plls in cogs, only some fake counters which give good frequency but with a good amount of jitter.

msrobots

@Bob,

well said and a nice way to put it.

Bob Lawrence (VE1RLL) wrote: »

... I suddenly realized that my Chinese is no good at all...

happened to me with some other device ... I was feeling quite helpless...

Mike

Lawson

Red is the hardware P1. I've measured the rise time of the P1 pins driving 50 ohm coax to a 1GHz scope. The P1 has ~700-800pS rise/fall time which is much faster than any CMOS discrete logic chip. (the rise time of the scope is ~230pS so it's not limiting the measurements) I'd expect the cost and EMI optimized pins on the FPGA to be much slower.

Marty