[time-nuts] Frequency Dividers
SAIDJACK at aol.com
SAIDJACK at aol.com
Thu Aug 10 02:47:35 EDT 2006
In a message dated 8/9/2006 20:29:22 Pacific Daylight Time, didier at cox.net
yes, its great fun to use, and much easier as well (SRAM addressing in 8051
BTW: I measured the 1PPS output jitter (generated by an LPC "Match" output
pin driven by an internal 60MHz PLL) on my Wavecrest DTS-2070C Jitter
analyzer: it's about +-100ps. This is equal to +-1E-010 per second stability.
Then I measured the 1PPS output of my SRS PRS-10 Rubidium standard: it has
about +-120ps jitter! Wonder what the best CMOS dividers can do.
On Digikey, the LPC2101 Arm is $3.15 for a single piece, and the SIL
8051F310 is >$6 for one! Tough choice. The 8051 does have one big advantage: it is
cycle accurate, and fun to program in assembly. The Arm is really a "C"
device, somewhat tough to program in assembly.
There is a lot of public domain info and software on the Yahoo LPC2000
discussion group: _http://groups.yahoo.com/group/lpc2000/_
Keil also supports the LPC Arm out-of-the-box with ready-made examples; I
think you can get an eval version for free.
For timing apps, the Arm has much better timer/counters/Capture-and-Match
units than the 8051's.
Thanks for the info, I did check the Philips (and Sparkfun) web site(s)
and I must admit the ARM chip is cheap and has impressive
specifications. With the GNU tools, I know it will work and it will fit
my homebrewer's budget :-) I used to consider $99 for a development kit
cheap, but $29 beats it with good margin.
At that price, I don't see how I could pass on a chance to evaluate it,
if not for the fact that I have so much 8051 code (and a Franklin
compiler, wich is similar to the Keil)
I agree that the Silab chips are somewhat expensive, at least for high
volume consumer stuff. However, I do not consider 64k of Flash memory
(and several kB of RAM for most parts) as small for an 8 bit micro, but
there again, if you are considering applications that require large
buffers, such as data compression, you probably would not want to use an
8 bit chip anyhow. Also, on the 8051, addressing RAM above the customary
128 bytes of DATA space (XDATA) takes a lot longer. On the 8051, RAM is
not always equal :-)
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