Multifunction adapter board for Raspberry Pi 4B

The board has provision for 3 pulse inputs (into 50 Ohm, any level from about 1 V to 5 V will work) and two buffered (50 Ohm, ~ 1.5 V) pulse outputs. It also has provision for a character LCD display and a small (4 key) keypad. Two UARTs (4 & 5) are buffered (choose between TTL and RS232 levels), and the primary UART is made available (buffered) with a 5V supply line. The idea is to attach an external microcontroller with a graphical display to act as a simple human-machine interface. I'm working on something with the Raspberry Pi Pico for this purpose. The boards were made quickly and precisely. As always (I'm a long time user of PCBWay) the service was excellent.