These Si570's appear to be available with lots of different start-up or
clock frequencies. i admit to being a bit confused about the relationships
startup vs clock here. But you can arrive at the start up frequency from
the part number. See the chip datasheet part ordering section for details.
Suggestion. Apply power to Si570 chip while disconnected from I2C. To make
sure software does not change frequency. Measure frequency output.
Change code line below to match your default power up frequency:-
#define FREQ_XTAL (114292532l)
What does it look like now?
Yes I think we are going to need a once only setup routine in firmware.
Si570 chip seems to store stuff like the startup frequency in registers.
Unclear at this point if we store offset data in NV storage in AVR or if
you can update Si570 registers. Still reading... Learning...
Hi,
I finalized the digital board tonight and was checking the output
frequency
of the si570 and I found a somewhat important error which seems to be
related to the vfo frequency.
[image: Inline image 1]
This error seems to be linear and could easily be corrected in software
but
for example when I set 14.200 on the VFO, my frequency meter counts
34.2133
mhz.
Is this something you are seeing as well? Should we add a calibration step
to measure and correct this error? Or is my Si570 just bad?
Full measures here:
https://docs.google.com/spreadsheet/ccc?key=0As9CZnZ-A5a2dEZaM1dlWVdVX3pXaUlJMXd0cHNscHc#gid=2
cheers,
thomas
