It seems like there is always a new toy to play with in the hobbysist electronics world, and while not entirely new, if you haven’t seen the color displays based on the ST7735 and ST7789 driver chips, David Johnson-Davies’ latest Technoblogy post is worth a look just for that.
Displays using these chips in several flavors, but the 80×160 pixel variety seen at the top of the page is barely bigger than the ATtiny85 microcontroller running it. Perhaps that’s a bit of an exaggeration, but it’s 0.96” diagonal dimension doesn’t exactly dwarf the ATtiny85 either, yet with this library it’s shown displaying a rather involved graph in four distinct colors — or five if you count black.
Johnson-Davies’ library allows you to plot points, draw lines, fill rectangles, and even plot scaled text. It doesn’t require a memory buffer, so it can be run on a wide range of processors. These displays communicate via SPI, requiring four microcontroller pins to communicate, leaving one pin open if you’re running it with an ATtiny85 to read a sensor or do other tasks. Of course, more capable chips can be used if you need more IO bandwidth.
The library has been tested with several Adafruit products, and would presumably work with other options from AliExpress, Banggood, and other online parts sources. If you prefer to work with self-lit OLED displays, Johnson-Davies has published a similar library for those as well in a previous post.