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10 February, 2020

Si5351 GPS corrected VFO up and running

Arduino Nano, Si5351A clock generator, I2C LCD display, and rotary encoder. The GPS signal is connected to the plug to the lower left.
I got the Si5351A Arduino controlled GPS corrected VFO designed by W3PM, Gene Marcus, up and running the other day. It gets its timing information from a QRPLabs GPS and all the functions in the original article function as they should. The main change I made was to use an LCD display running over the I2C bus, thus saving a bunch of wires from the Arduino Nano to the display.

The software worked fine except that my locator was one off in the last letter, i.e. JO59fs rather than JO59fu. I hacked the original code by adding "1" to the variable GPSlocator[5] in the calcGridSquare routine. This is not a tested fix and it may possibly have other unknown and undesirable consequences, but it works in my location.

My plan is primarily to make a 10 MHz reference oscillator out of this, as a replacement for my "Just good enough 10 MHz GPS reference" which turned out to generate too much noise in the 14 MHz band.

Now on to decide what I want to show on the 2-line display for my use and then play with Arduino code. What I definitely want is some form of indication of correction factor and thus accuracy as in the version that F2DC built.


This blog post first appeared on the LA3ZA blog.
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3 comments:

  1. JACK06 August, 2020 00:21

    Sverre,
    I modified Gene's code once to use a 1602_12c but now it won't compile. Would you kindly share your script with me. I would really appreciate it
    Jack W6VMJ

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    Replies
    1. Sverre Holm11 September, 2020 09:16

      In the end I gave up on that code and built on the F2DC code instead, see follow-up here https://la3za.blogspot.com/2020/09/gps-corrected-10-mhz-reference.html and check his website for the latest version.

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  2. Anonymous09 December, 2022 03:06

    Hello. If still interested, I modified his original code to work with i2C displays. I have also over the last couple of years heavily modified his code to work on an ESP32 which I am using a TFT color display. Ive had a few boards made but have not built one yet to test. It has the si5351 built on the board. I am currently creating my blog about the build to use with my Kenwood TS-520. K7ILO@outlook.com

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