I like TR-52D series IQRF, but in some cases, these modules has insufficient number of IOs (6 only). I mentioned this issue in this post. Unlike Relay board, I want 8 input pins (and more). So the simpliest way, how to do It, is port expander usage.
This article is simple demonstration, how to use popular shift register 74HC595 as output port expander for IQRF TR-52D module. I use It as simple remote switch unit for my workshop at oposite side of garden. Simply, from serial terminal or single purpose software written in C#.