YunSerialTerminal

Yún Serial Terminal

This example allows you to use the Yún's 32U4 processor or the microcontroller of the board attached to the shield as a serial terminal for the Linux processor.

Upload this to a Yún device via USB (not over WiFi) then open the serial monitor at 115200bps to see the boot process of the Linux processor. You can also use the serial monitor as a basic command line interface for Linux using this sketch.

From the serial monitor the following commands can be issued:

'~' followed by '0' -> Set the UART speed to 57600 baud
'~' followed by '1' -> Set the UART speed to 115200 baud
'~' followed by '2' -> Set the UART speed to 250000 baud
'~' followed by '3' -> Set the UART speed to 500000 baud
'~' followed by '~' -> Sends the bridge's shutdown command to obtain the console.

Hardware Required

Yún board or shield

Circuit

There is no circuit for this example.

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Code

Create a variable to hold the baud rate at which the processors will communicate and a variable to determine if entering command mode or not.

long linuxBaud = 250000;
boolean commandMode = false;

[Get Code]

Open the serial connection to the computer and Linux in setup()

void setup() {
Serial.begin(115200);
Serial1.begin(linuxBaud);
}

[Get Code]

In the loop() copy data from one serial connection to the other. If the "~" character is passed, enter command mode.

void loop() {
// copy from virtual serial line to uart and vice versa
if (Serial.available()) { // got anything from USB-Serial?
char c = (char)Serial.read(); // read from USB-serial
if (commandMode == false) { // if we aren't in command mode...
if (c == '~') { // Tilde '~' key pressed?
commandMode = true; // enter in command mode
} else {
Serial1.write(c); // otherwise write char to Linux
}
} else { // if we are in command mode...
if (c == '0') { // '0' key pressed?
Serial1.begin(57600); // set speed to 57600
Serial.println("Speed set to 57600");
} else if (c == '1') { // '1' key pressed?
Serial1.begin(115200); // set speed to 115200
Serial.println("Speed set to 115200");
} else if (c == '2') { // '2' key pressed?
Serial1.begin(250000); // set speed to 250000
Serial.println("Speed set to 250000");
} else if (c == '3') { // '3' key pressed?
Serial1.begin(500000); // set speed to 500000
Serial.println("Speed set to 500000");
} else if (c == '~') {
Serial1.write((uint8_t *)"\xff\0\0\x05XXXXX\x0d\xaf", 11);
Serial.println("Sending bridge's shutdown command");
} else { // any other key pressed?
Serial1.write('~'); // write '~' to Linux
Serial1.write(c); // write char to Linux
}
commandMode = false; // in all cases exit from command mode
}
}
if (Serial1.available()) { // got anything from Linux?
char c = (char)Serial1.read(); // read from Linux
Serial.write(c); // write to USB-serial
}
}

[Get Code]

Below is the complete code:

/*
Arduino Yún USB-to-Serial

Allows you to use the YunShield/Yún processor as a
serial terminal for the Linux side on the Yún.

Upload this to a YunShield/Yún via serial (not WiFi) then open
the serial monitor at 115200 to see the boot process of Linux.
You can also use the serial monitor as a basic command line
interface for Linux using this sketch.

From the serial monitor the following commands can be issued:

'~' followed by '0' -> Set the UART speed to 57600 baud
'~' followed by '1' -> Set the UART speed to 115200 baud
'~' followed by '2' -> Set the UART speed to 250000 baud
'~' followed by '3' -> Set the UART speed to 500000 baud
'~' followed by '~' -> Sends the bridge's shutdown command to
obtain the console.

The circuit:
YunShield/Yún

created March 2013
by Massimo Banzi
modified by Cristian Maglie

This example code is in the public domain.

http://www.arduino.cc/en/Tutorial/YunSerialTerminal

*/

long linuxBaud = 250000;

void setup() {
SERIAL_PORT_USBVIRTUAL.begin(115200); // open serial connection via USB-Serial
SERIAL_PORT_HARDWARE.begin(linuxBaud); // open serial connection to Linux
}

boolean commandMode = false;

void loop() {
// copy from USB-CDC to UART
int c = SERIAL_PORT_USBVIRTUAL.read(); // read from USB-CDC
if (c != -1) { // got anything?
if (commandMode == false) { // if we aren't in command mode...
if (c == '~') { // Tilde '~' key pressed?
commandMode = true; // enter in command mode
} else {
SERIAL_PORT_HARDWARE.write(c); // otherwise write char to UART
}
} else { // if we are in command mode...
if (c == '0') { // '0' key pressed?
SERIAL_PORT_HARDWARE.begin(57600); // set speed to 57600
SERIAL_PORT_USBVIRTUAL.println("Speed set to 57600");
} else if (c == '1') { // '1' key pressed?
SERIAL_PORT_HARDWARE.begin(115200); // set speed to 115200
SERIAL_PORT_USBVIRTUAL.println("Speed set to 115200");
} else if (c == '2') { // '2' key pressed?
SERIAL_PORT_HARDWARE.begin(250000); // set speed to 250000
SERIAL_PORT_USBVIRTUAL.println("Speed set to 250000");
} else if (c == '3') { // '3' key pressed?
SERIAL_PORT_HARDWARE.begin(500000); // set speed to 500000
SERIAL_PORT_USBVIRTUAL.println("Speed set to 500000");
} else if (c == '~') { // '~` key pressed?
SERIAL_PORT_HARDWARE.write((uint8_t *)"\xff\0\0\x05XXXXX\x7f\xf9", 11); // send "bridge shutdown" command
SERIAL_PORT_USBVIRTUAL.println("Sending bridge's shutdown command");
} else { // any other key pressed?
SERIAL_PORT_HARDWARE.write('~'); // write '~' to UART
SERIAL_PORT_HARDWARE.write(c); // write char to UART
}
commandMode = false; // in all cases exit from command mode
}
}

// copy from UART to USB-CDC
c = SERIAL_PORT_HARDWARE.read(); // read from UART
if (c != -1) { // got anything?
SERIAL_PORT_USBVIRTUAL.write(c); // write to USB-CDC
}
}

[Get Code]

Yún Serial Terminal

Hardware Required

Circuit

Code

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