Re: Si570 Set Frequency

wb6ogd
 

The Si570 is a tricky beast!
Craig AA0ZZ conquered the programming using pre-calculated tables like Nick said.

Silicon Labs has an app note that has C code for one of their microcontroller chips.
I was able to port that to a PIC using Microchip's free C compiler but it took up almost
all the memory  :(

BUT Arduino's run C and pretty efficiently.  I would get the app note and port it to
Arduino.  The actual code that sets the frequency is only a few lines.  It is probably
not as fast as the integer calculation/table method.

If you could use the Si5351, there are Arduino libraries available to do it.  Is easy,
I have been using the Etherkit library and board for a few years now.

I have both an AD9851 (DDS-60) and Si5351 in my PHSNA using modified Nick code
with LCD and encoder for local standalone.  It is my favorite piece of test equipment,
thanks to Nick and PHSNA group!!
Code is posted in the Files area.
73,
Gary
WB6OGD

On 4/14/2019 1:55 PM, Nick Kennedy wrote:
For this program it might take a bit of work. The program is set up to have
pre-calculated register values for all frequency ranges within the
specified limits, so the amount of calculation required for a small change
within a band is minimized. So you would need to expand the tables of
values all the way up to your desired 440 MHz limit to continue with that
method.

There's no reason you couldn't do it, but you'd have to study the code
(and/or the AA0ZZ QEX article) a bit to understand how the tables are
constructed.

I have expanded this basic program to one that includes display, rotary
encoder, TX/RX offset and so on, but I haven't expanded the frequency
limits because the version of the Si570 that I'm using is only specified to
160 MHz.

Good luck with it.

73-

NIck, WA5BDU

On Sun, Apr 14, 2019 at 12:59 PM Alfredo Mendiola Loyola via Groups.Io
<mendiola_loyola=yahoo.com@groups.io> wrote:

Hello:

I have found this Arduino code to set the Frequency on a si570 oscillator
but it has a max frequency of 157 Mhz (#define ULIMIT 157000000UL),

Is there a way to modify the source code to make it work until 440 Mhz ?

I would like to set frequencies from 430 to 440 mhz.

http://pages.suddenlink.net/wa5bdu/Si570_New.ino

Regards
Alfredo Mendiola
OA4AJP



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