[minima] Re: Auto-calibration of the Si570 + some refactoring
- From: Thomas Sarlandie <thomas@xxxxxxxxxxxxx>
- To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
- Date: Mon, 10 Feb 2014 10:24:16 -0800
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> 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>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
>>
>
>
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