SMAKN&reg; DIY Ds1302 Rotation LED Electronic Clock Kit 51 SCM Learning Board Size: 81 mm x 81 mm x 1.6 mm. PCB thickness: 1.6 mm. Materials: FR4 military level. PCB color: blue. Digital Tube display: red. Power supply voltage: miniUSB, external connection 5V ,3V button battery for clock chip on the board of the standby power supply. Key Function: PLUS key, for years, months, days, hours, minutes, seconds add operation. According to the numerical sum 1 at a time &lt;br&gt;MODE key, can be in display clock, switch to the year, month, day, hours, minutes, alarm clock, the adjustment of outer ring LED display state. To use add key to the year, month, day, hours, minutes, seconds, and display mode to adjust RST key, press the reset button, then the MCU reset. Package included: 1 x Rotation LED Electronic Clock Kit. Many mode display function. Outer LED display has four modes, can cooperate to add key implementation, through the model key Mode 0: is also the default display mode, all the 1-12 hours red digital tube light, when the clock through a second, is the green digital tube is take turns to light up a. Mode 1: as the clock through a second, outer ring LED lit one by one, that is 60 seconds, outer ring all the LED light. The next minute, all leds light up, and through the clock for a second, put out one by one. And the next minute, leds light up one by one again, so alternates. Mode 2: when the clock through a second, outer ring take turns to light up a LED. The first seconds, only the first LED light, 2 seconds only the second LED light. Mode 3: when the clock through a second, outer LED turns off a. The first seconds, only the first LED out, only the second LED out 2 seconds.