Breathing new life into an old LCD shield
Background The latest generation of inexpensive microcontrollers have some capabilities that can be utilized in a variety of ways. One of them is the ability to quickly write parallel data with optional DMA ( direct memory access ) to drive the operation. The Raspberry Pi Pico not only has lots of exposed IO, but it contains a very flexible IO state machine that can run simple 'PIO' programs to manipulate IO with precise timing. The good folks at Pimoroni reminded me of this recently with the release of their Tufty2040 product. The board features a RP2040 MCU along with a lovely ST7789 IPS 240x320 color LCD. The bold move they made was to take the extra effort to connect it on an 8-bit parallel bus instead of the usual 1-bit SPI. This change allows the LCD to rewrite its entire content more than 60 times per second. To clarify, the RP2040 has no video output, but inexpensive LCDs like the ST7789 have their own internal video RAM and can be told what to display with a serie