I spent most of the holidays visiting relatives. and had quite a bit of time to work on something I had been thinking about doing for a while. I have been following the development of the Simple-Ceiver that Pete N6QW has been posting on his blog. N6QW.blogspot.com .
Pete spends a lot of time going through the design of a DC receiver that is later converted to a single conversion heterodyne receiver for 40 meters. He goes through the design using LTSpice to simulate each stage before he builds them. This powerful tool allowed him to optimize the circuit design before melting any solder.
I have a bunch of 12 mHz. crystals left over from the IF amplifier for the Specan, so I could use the same frequency scheme that Pete used. I plan on using a version of the SI5351 VFO I had built for the "Canned Frog" transceiver. Different from Pete's circuit I will use another clock output from the SI5351 for the BFO.
Link to schematic at https://www.dropbox.com/s/dersy23jgj6h37c/Simple-ceiver-schematic.pdf?dl=0
After drawing the schematic and getting it checked by Pete, I did a single sided board layout using mostly surface mount components. I did not have surface mount versions of the ICs for the AF amplifier so I did the layout with extended solder pads for the leaded components. Although I plan on using the SI5351 for the BFO, I decided to add the BFO oscillator to the board.
Etched the board now to start building and testing the receiver, first the audio amplifier stages.
Friday, December 4, 2015
I chose the project from http://michaelteeuw.nl/
that looked like it would be easy to port over to the hardware I have on hand. And of course it would fit in an Altoids tin.
I had an OLED like the display in my "Canned Frog", but it was two color instead of monochrome. I had a small TFT display left over from the DL Watt meter project, so decided to use that.
Looking a the schematic, it was very easy to take the board layout from that project and modify it for use for the PONG project. I was able to remove the Dummy Load and detector components from the board, and move the Arduino Pro Mini and display up towards one end of the board to give room for the two pots I needed for the game controls. Only other thing was to bring out a pin to connect a small speaker.
After etching the board and installing the components, I started on porting the software to work with the TFT display. The main advantage of the software I chose, was that it had used the Adafruit graphics library. I had a compatible library for the TFT display I was using, so it was only took an hour or so to make the necessary changes to use this display.
Main changes was in the resolution of the display, and handling the different colors available to this display. The OLED display has a clear() function that was used during the draw routine that was not available in the TFT library. I tried to replace this with a fillScreen(color) function. Unfortunately this was much too slow and there was a lot of jiter. Instead of filling the whole screen, I used the fillRectangle(color) function to only clear areas that needed to be redrawn. This was much faster, and greatly reduced the amount of jitter. Just a couple of other changes of game play and the porting was finished.
The part of the project that took the longest was cutting and aligning the holes in the Altoids tin.