What is in the Sunfounder IoT Shield Kit?The kit consists of two boxes, one containing a Gateway Shield and the other a Node Shield. The latter comprises an I/O shield and a small NRF24L01 wireless module. The gateway shield has an on-board NRF24L01 module and a (mobile phone) LCD; an 4×4 keypad with cable and an ESP-01 Wi-Fi module are separate.
The Node ShieldThis is an Arduino add-on board containing three relays, eight LEDs and a pushbutton. Also a bunch of 3-way pin headers are available for connecting sensors and other things: three analogue inputs (A0, A1 & A2, that can, of course, also be used as digital I/O) and two purely digital I/O ports (D6 & D7). These five ports each have two 3-way headers, one with +5V and the other with +3.3V.
The designer of the Node Shield has left no stones unturned to get the most out of the Arduino extension connectors. The LEDs are controlled by means of a 74HC595 shift register, which in turn is connected to ports A3-A5. The pushbutton is connected to D2. With D0 & D1 as serial port, this leaves ports D8-D13 for communicating with the NRF24L01 module.