Thomas,
Just to be clear, what I am suggesting is that the calibration
procedure would initially present on the display a 'common'
start-up frequency for the Si570. As an example, the CMOS
Si570 that is sold by KM5H
http://km5h.softrockradio.org/index.php?route=product/product&product_id=49
has a start-up frequency of 56.32 MHz. If it is agreed upon that
that start-up frequency is commonly used, then that would be the
frequency value initially presented to the operator. If the
Si570 actually being used has a different start-up frequency,
then the operator can use the potentiometer to change the initial,
value to the actual value. For example, the CMOS Si570 that I
have has an initial start-up frequency of 10 MHz, so I would
adjust the frequency setting displayed accordingly prior to
pushing the function button to accept the value displayed. I
hope this makes sense to you.
73,
Mac AE5PH
On 02/10/2014 12:24 PM, Thomas Sarlandie wrote:
Dan,
Latest version of my code will always be available in my github
repository:
https://github.com/sarfata/radiono
The code I was mentioning yesterday has already been merged by Farhan
and so you will get all my changes in the official version which is
available here:
https://github.com/afarhan/radiono
The rest of the discussion is about what is the best way to calibrate:
1 - Using factory calibration settings in the chip - but we need a
way for the user to find out this frequency and give it to the program
(maybe through a menu like what Mac suggested)
2 - Starting with no calibration and a fixed output frequency
(10Mhz). Ask the user to adjust until it is perfectly 10mhz.
Both method will play nicely with my changes. Nothing was lost ;)
best,
thomas
On Mon, Feb 10, 2014 at 9:50 AM, Dan Reynolds <on30ng@xxxxxxxxx
<mailto:on30ng@xxxxxxxxx>>wrote:
Thomas, I would still like to see your code if possible.
73
Dan -- KB9JLO
https://sites.google.com/site/on30ng/
On Sun, Feb 9, 2014 at 8:27 PM, Thomas Sarlandie
<thomas@xxxxxxxxxxxxx <mailto:thomas@xxxxxxxxxxxxx>>wrote:
Hi everyone!
Spent some time this week-end on the Radiono software. I found
out earlier this week that my Si570 had a very large error
that grew linearly with frequency. We quickly found out that
each module is different and you need to use calibration
information that is saved in the module. The current source
code has Farhan's si570 calibration hardcoded in. That will
most likely not work for you.
I have updated the Radiono source code to automatically get
the calibration information and calculate the crystal
frequency every time we start the program. The only
information that needs to be defined in the source code is the
default frequency programmed by the factory. In my case it was
56.320 but your mileage may vary.
There are two ways to find this frequency:
- Spec: Look on the marking on your Si570 (mine says
CAC000141) and lookup some tables online to find which
frequency corresponds to your marking (I cant find this table,
if someone has it, please share!)
- Experimental: just remove the Arduino and apply power to
the control board. Measure the frequency at the output of the
Si570.
I have updated the wiki:
http://www.hfsignals.org/index.php/Si570
The updated source code has been submitted to Farhan in a
pull-request:
https://github.com/afarhan/radiono/pull/4
Full list of changes:
Split the Si570 code in a separate class.
In the Si570 class:
* Use the factory-calibrated output frequency to automatically
calculate the internal crystal frequency and use that instead
of hard coded values.
* During initialization detect errors talking to the Si570.
* Use multi-bytes i2c reads and writes when possible (ie:
read/write multiple bytes without re-starting a transaction).
Only works for read/writes in consecutive registers.
* Use types with explicit size where that makes sense (uint8_t
instead of char, uint64_t, etc)
* Added some debugging on the serial console through a "debug"
function
In the main sketch:
* Show a message on the LCD if the Si570 is unreachable.
* Initialize the serial port for debugging
* Fix some compilation warnings with string litterals being
casted to char*
* Removed unused variables
And now, back to the soldering iron!
73,
thomas
