Keyestudio ARDUINO maker learning kit, Manual

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97
Serial.println(" V"); // Serial port outputs character V, and begin a new line
temp = vol;
delay(1000); // Wait 1 second after the output is complete for controlling the data refresh rate.
}
}
//////////////////////////////////////////////////////////
Result
Click and open the serial port monitor; use the red line to measure battery positive pole, black line
for negative pole. Serial monitor will refresh the voltage at 1 time/second. It is normal if there is
fluctuation between two voltage values because it is, after all, a low accuracy test.
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Project 23: 74HC595
Introduction
To put it simply, 74HC595 is a combination of 8-digit shifting register, memorizer and equipped
with tri-state output. Here, we use it to control 8 LEDs. You may wonder why use a 74HC595 to
control LED? Well, think about how many I/O it takes for an Arduino to control 8 LEDs? Yes, 8.
For an Arduino 168, it has only 20 I/O including analog ports. So, to save port resources, we
use 74HC595 to reduce the number of ports it needs. Using 74HC595 enables us to use 3 digital