OLED display with graphing
I replaced the 2-line LCD display with a 128x64 OLED. The attached pic shows the results of a 1-30 MHz sweep. The antenna is a 16.2 meter wire being fed into a 9:1 unun. The tick marks at the bottom of the screen show the location of the 10 bands. The vertical line can be scrolled using the MODE button so I can review the SWR at various freqs; the pic shows a SWR of 1.0 at 21.844 MHz.
There is also a screen that displays the SWR at the center frequency of each band.
BTW, people are loving this on the Ham Radio 360 Facebook page.
The display was $50 at Adafruit ( https://www.adafruit.com/products/2674 ). I'm sure they are available from China for less but I didn't want to wait for the shipping. I used an Perma-Proto board to build an adapter to convert from the header pins on the board to the ones on the OLED. I used software SPI on the Arduino and was able to reassign the LCD pins to SPI. This weekend I'm going to add a rotary encoder so I can quickly scroll through frequencies. I'll post my notes and the code as well.
Here are some pictures of the adapter that converts between the LCD and OLED pinouts. Both the AA board and the OLED module are fitted with male headers and the adapter fits between them. The OLED requires 5 pins for SPI so I repurposed Arduino pins 8, 9 , 10, 15, and 16 as SPI DC, CS, RESET, SCLK, and MOSI. The chip is a level shifter that converts between the AA's 5V and the OLED's 3.3V (it came with the OLED module).
I also attached the Arduino code. I haven't cleaned it up yet so it is pretty rough.