[minima] Re: Auto-calibration of the Si570 + some refactoring
- From: Thomas Sarlandie <thomas@xxxxxxxxxxxxx>
- To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
- Date: Tue, 11 Feb 2014 01:02:43 -0800
Mac: Yes we 100% agree.
Steve/Farhan: We will make sure to keep some way to adjust the crystal
frequency manually.
I would love to get started writing this but I want to get my minima in
working conditions first and that means melting solder for a little while
instead of writing code ;) If someone else wants to pick this up, I would
be happy to review and comment pull requests!
73,
thomas
On Tue, Feb 11, 2014 at 12:45 AM, <farhanbox@xxxxxxxxx> wrote:
> Steve, a frequency counter is not a must. You can accurately set it with a
> 10 MHz receiver. It might even be far more accurate if you can beat it to
> WWV.
>
> Sent from BlackBerry® on Airtel
>
> -----Original Message-----
> From: "Steve VK2SJA" <vk2sja@xxxxxxxxxxx>
> Sender: minima-bounce@xxxxxxxxxxxxx
> Date: Tue, 11 Feb 2014 19:07:40
> To: <minima@xxxxxxxxxxxxx>
> Reply-To: minima@xxxxxxxxxxxxx
> Subject: [minima] Re: Auto-calibration of the Si570 + some refactoring
>
> Some random thoughts:-
>
> Two calibration methods exist.
>
> 1. Manually enter the start-up frequency. Software uses this value along
> with additional values retrieved from the Si570 chip to calculate the
> actual reference crystal value.
>
> 2. Instruct Si570 to output known frequency, say 10Mhz and adjust up and
> down the software crystal reference value until the output on a frequency
> counter is exactly 10Mhz.
>
> Both methods have some Pros and Cons.
>
> Method 1:-
> You don't need a Frequency Counter
> You need to know your Si570 start-up frequency (might prove awkward
> finding this out without a counter - negates not needing one)
> Accuracy is good. But Tomas's own results seem to show that +/- 300 Hz
> might not be an unreasonable expectation.
>
> Method 2:-
> You DO require a frequency counter of some sort.
> Accuracy will only be as good as the counter.
> You don't need to know the Si570 start-up frequency.
> It is probably reasonable to expect errors of only +/- 3 Hz after
> calibration
>
> Not every person owns a Frequency Counter. I will even allow that it is
> possible that someone building a Minima may not own one.
>
> So I would actually suggest having both methods available via a Firmware
> set-up routine. Since most of the extra code would deal with changing a
> value via the VFO pot. And both methods require this. A significant
> portion of the code should be able to be shared between both methods.
>
> I'm thinking something along the lines of:-
>
> Press and hold Function button while powering up Minima to enter setup
> routine. Use VFO knob to cycle through setup options. Press enter to
> select the one you want. One option can be to exit setup. Something like
> this:-
>
> Setup
> Calibrate 1 -> Calibrate 2 -> Other Options we haven't thought of yet ->
> Quit -> Back to Calibrate 1
>
> When you enter either Calibrate 1 or 2 the user interaction is much the
> same. With one you are adjusting the crystal reference frequency up and
> down until you get exactly 10Mhz on the counter. With the other you are
> adjusting the value of the start-up frequency up or down until it matches
> your known Si570 start-up frequency. In both cases you press the Function
> button to accept and save the new value. Which returns to the top level
> setup menu.
>
> There is even a logical progression in doing both calibration routines in
> order 1 and 2. While entirely non-essential Calibrate 2 could use the
> calculated value produced by Calibrate 1 as its starting point. Which
> would put it very close to the correct value.
>
>
> Anyway just some random thoughts out loud.
>
> 73, Steve.
>
>
>
>
>
>
>
>
>
> > 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
> >>
> >>
> >>
> >
> >
>
>
>
>
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