And all of the GPIO pins are conveniently broken out ... Once the UART port is identified, a single terminal command frees its status as a debugging interface. After that, use any terminal ...

The installed PiDP-11 I/O Expander Each expander board gives you 16 GPIO pins which can be accessed over I2C, including support for interrupts which has been connected to GPIO 19 on the Raspberry Pi.

Here’s how this one works. Between conversions, U1’s reset pin 4 is held active-low either by the connected GPIO pin, or by U1 itself. Using a 555 in this self-resetting mode is unusual but is very ...