Sunday, March 4, 2018

Sweeprino Jr revisited Update 3/16/18

Well after three weeks of feeling terrible and not having the ambition to do anything, I finally got over what ever version of the 'flu' I had.  This has put me quite a bit behind in working on the next article in the series of Arduino building blocks for QQ.  Over a year ago I had started on a version of Farhan's Sweeperino project. at  I knew this would make a great basis for the next article

Since this was  to be a stand alone instrument or connect to a PC to use Farhan's  'Specan.exe' software, I made some changes to my Arduino/display building block.  I changed from a pro-mini to a Arduino Nano.  This gave me the USB interface to a PC, brought out the I2C lines that do not have dedicated pins on the pro-mini.  The Nano also has a heavier duty voltage regulator on the 5 volt line.  This will allow me to run a Adafruit SI5351 board with out having to add additional voltage regulation. I also added a rotary encoder with push button to use as the interface to the software.

Doing the board layout for these changes was very easy.  Mainly because except for the form factor, it is very near to what I did to make the stand alone VFO/BFO board for Pete's Simpleceiver project.  Instead of making my own boards this time, I took advantage of a promotional offer by one of the Chinese board houses.  For a limited time they had offered 10 boards for a little over $5 and free shipping. 
 I couldn't even buy the raw pcb material for that price.  After they arrived and I built one up, I found a small error I had made in the board layout.  One end of a resistor was grounded that should not have been.  After discovering the error, about 30 seconds with a hobby knife took care of the problem.  Also modified the 3D printed case I had designed for earlier projects in the series to fit the new board

I pulled a copy of Farhans sketch, and made changes to use a tft display instead of the 2 line LCD he had in his original unit.  The first cut of the software worked with the PC interface, and a simulated two line  LCD display on the TFT display.  

After making sure everything was working I decided to use the graphic capabilities of the TFT display.  In previous projects, I had used simple bar graphs to give a analog representation of values, to make tuning easier than just a digital value.  I was real happy with the simulated analog meter I came up with for the uBITX, so I incorporated it in the new display screen for the manual operation mode.   I made a few changes to the basic code  so I could also display the actual value as a number along with the analog meter.    Still trying to decide if I want to add a sticky needle in a slightly different color to indicate the peak reading for the last few seconds.  Will only take a couple lines of code, but not sure if it will be necessary.  For the frequency setting display, I decided to show the digit that is changed by the rotary encoder in a different color than the rest of the value.  So a short push on the encoder button moves the active digit around in a circular manor.

Need to do a little more checking of the software so far. Then the only other thing I want to add is a graphic sweep waveform very similar to what I have on my SNA Jr.  Just going to be very basic, so everyone can add any additional functions they want.

Will keep you informed, but I also have to hurry up and write the article for QQ to have it ready for the next issue.  Maybe this time they can get the author correct.

Update 3/16/2018

Finally finished the QQ article on the Sweeperino Jr so far.  I decided to make this two articles instead of just one.  The first one will have the Sweeperino Jr with the same basic functionality as the original.  In the next article, I will add a graphical sweep function similar to the SNA Jr.  I have the latest Eagle file Gerber files , and Arduino sketch in a dropbox folder for any one interested in building one of these.

It works quite well, if you understand that there are going to be some issues with harmonics because of the square-wave output.  I am working on a method to get rid of that problem, and mostly finished with the preliminary design for the SNA Jr. version III.  Hope to get around to finishing that in the near future.