Reply by Jim Granville●December 14, 20052005-12-14
diggerdo wrote:
> Don't use a 8051. Takes 12 clocks to execute one instruction.
> Use a modern micro that has a "capture" function.
>
> Something like an Atmel ATmega88.
>
> If you must use the 8051, use a variant. Dallas Semi (now Maxim)
> makes a tripler that executes instructions every 4 clock cycles.
> Crystal makes the only 8051 that executes an instruction in one clock cycle.
You should update your info :
I think you meant Cygnal, now Silicon labs ?
Their C51's clock to 100MHz
Atmel also make 1 cycle AT89LP2052's; clocks faster than the Mega88.
Maxim have 1 cycle 89C51's, also clock faster than the Mega88....
Others are also doing 1 cycle 80C51's....
Pretty much everything above the lowly 89C52, has Capture ability.
-jg
Reply by Ian Bell●December 14, 20052005-12-14
diggerdo wrote:
> Don't use a 8051. Takes 12 clocks to execute one instruction.
This is irrelevant unles very high speeds are necessary in which case there
are plenty of modern 8051s that execute in 6, 4 or even single cycles
> Use a modern micro that has a "capture" function.
>
'Modern' 8051 variants have capture functions. The advantage of the 8-51 is
a wide range of hardware and performance variants to choose from but a
common instruction set and development tools.
Ian
Reply by diggerdo●December 14, 20052005-12-14
Don't use a 8051. Takes 12 clocks to execute one instruction.
Use a modern micro that has a "capture" function.
Something like an Atmel ATmega88.
If you must use the 8051, use a variant. Dallas Semi (now Maxim)
makes a tripler that executes instructions every 4 clock cycles.
Crystal makes the only 8051 that executes an instruction in one clock cycle.
"zotdall" <kabacik@gmail.com> wrote in message
news:1134317937.058382.117790@g43g2000cwa.googlegroups.com...
> is there any body knows how i can build ''6-digit frequncy meter'' by
> using 8051 (or 8052).?
>
>
Reply by Everett M. Greene●December 13, 20052005-12-13
"zotdall" <kabacik@gmail.com> writes:
> i have to build it for my microcontroler lesson, and i will not use it
> for money ofcourse. it should have LCD screen.
You could always connect a controller to a frequency
meter via GPIB.
Reply by zotdall●December 12, 20052005-12-12
i have to build it for my microcontroler lesson, and i will not use it
for money ofcourse. it should have LCD screen.
Reply by Rocky●December 12, 20052005-12-12
zotdall wrote:
> is there any body knows how i can build ''6-digit frequncy meter'' by
> using 8051 (or 8052).?
> is there any body knows how i can build ''6-digit frequncy meter'' by
> using 8051 (or 8052).?
It's only possible if you want a fairly low spec unless you use an
external counter/timebase and just use the micro to control it.
Reply by Paul Keinanen●December 12, 20052005-12-12
On Mon, 12 Dec 2005 10:43:15 +1300, Jim Granville
<no.spam@designtools.co.nz> wrote:
>you can get 7/8+ digits of result at 1MHz Fin.
While you can get a large number of (meaningless) digits, you really
need an accurate time base/clock source. To get 6 meaningful digits,
you need a clock better than 1 ppm, for 7/8 digits, you would need
some kind of TXCO or run the crystal in a temperature compensated
oven. With a typical microprocessor crystal, you would expect to get 4
or 5 meaningful digits, unless you lock your time base to an external
accurate source such as GPS or NTP (with long integration times).
Paul
Reply by Jim Granville●December 11, 20052005-12-11
zotdall wrote:
> is there any body knows how i can build ''6-digit frequncy meter'' by
> using 8051 (or 8052).?
What is your target Fmax ? & Gate times ?
A generic old 89C52 is not the ideal device;
Look at AT89C51ED2, (newer, better peripherals),
or maybe the AT89LP2052, or C8051F3xx series.
The simplest scheme is to use the uC HW as much as possible;
for Freq you want Cycles/FixedTimeSample.
The 89C51ED2 allows true HW, where you use Timer2+T2OE, in FREQ_OUT
mode, to trigger a CAPTURE of the Externally [Fu] Clocked PCA
[Needs external wire T2 -> CEX0], on a fixed capture timebase.
Those hard-sampled cycle values are then further added/averaged in SW.
A 22.1184MHz Xtal and Timer2, reload value of 55296, will give 10ms
snapshot edges on T2 output pin, to capture the Fu counts.
Then total 10,50,100 of those, for 0.1, 0.5, 1.0 second gate times.
Fmax in is just over 5MHz, as the PCA counts at <= Pclk/4.
You want to avoid gated topologies, as they can have aperture effects,
and do not naturally scale.
With the capture design above, you can have a smart decimal point mode,
that gives a quick answer in the first 10ms, then another digit after
100ms, and another after 1 second (etc) - no edges are lost, so this
is possible : you can get 7/8+ digits of result at 1MHz Fin.
Once you have this mastered, you can really impress your tutor
by also doing a Reciprocal counter design - that gives high
resolutions, independant of input frequencies.
-jg
Reply by Donald●December 11, 20052005-12-11
zotdall wrote:
> is there any body knows how i can build ''6-digit frequncy meter'' by
> using 8051 (or 8052).?
>