We’ve typically used 9600 bps (or 9.6 kbps) for transmitting our debugging info. Both devices-in this case, the Arduino and the computer-need to be set to the same baud rate to communicate. The baud rate specifies how fast data is sent over serial, which is expressed in bits-per-second (bps). But what about the second function with byte config and what does this parameter mean? We’ll dig in to both below. Thus far, in our lessons, we have been using the first function- begin(unsigned long baud)-which sets the data rate in bits per second (baud). So, after Serial.begin() is called, you should not use Pins 1 and 0 (unless you’re using them for cross-device communication or to hook up your logic analyzer!). Once Serial.begin() is called, the Arduino Uno and Leonardo take over Pins 1 and 0 for serial transmission and reception, respectively, and the RX and TX LEDs light up on the board. The Serial.begin() function has two overloaded options: begin ( unsigned long baud ) begin ( unsigned long baud, byte config ) On Arduino, we initialize the serial port using Serial.begin(). However, we’ve glossed over the details and used serial primarily for debugging rather than Computer ↔ Arduino communication. We’ve been using Arduino’s serial functionality since our very first set of lessons ( e.g., 元: Serial Debugging). In this lesson, we’ll dive into asynchronous serial communication and how we can use it for bidrectional Computer ↔ Arduino communication. This has the benefit of fewer wires but does result in a bit of communication overhead for each transmitted “packet” or data frame. Unlike other popular serial communication protocols like I 2C and SPI, TTL serial is asynchronous, which means it does not rely on a shared clock signal (precisely timed voltage pulses) paired with its data lines. In this lesson, we will focus on asynchronous serial communication, specifically TTL serial (Transistor-Transistor Logic Serial)-an enduring standard that has prevailed since the beginning of personal computers and is what the Arduino Serial library uses. And beyond! Many different protocols have been created to support device-to-device communication from Ethernet and Zigbee to WiFi and Bluetooth.
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