Serial Ports (Serial1, Serial2, Serial3) — Maple v0.0.9 Documentation

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# Serial Ports (`Serial1`, `Serial2`, `Serial3`)

Used for communication between the Maple board and a computer or other devices.

Contents

- Introduction
- Library Documentation
- Arduino Compatibility Note

## Introduction

The Maple has three serial ports (also known as a UARTs or USARTs): `Serial1`, `Serial2`, and `Serial3`. They communicate using the pins summarized in the following table:

Serial port | TX, RX, CK | CTS, RTS (if present)
--- | --- | ---
`Serial1` | 7, 8, 6 |
`Serial2` | 1, 0, 10 | 2, 3
`Serial3` | 29, 30, 31 | 32, 33

Thus, if you use a particular serial port, you cannot also use its communication pins for other purposes at the same time.

If you want to communicate with the Maple using the provided USB port, use SerialUSB instead.

To use them to communicate with an external TTL serial device, connect the TX pin to your device’s RX pin, the RX to your device’s TX pin, and the ground of your Maple to your device’s ground.

Warning

Don’t connect these pins directly to an RS232 serial port; they operate at +/- 12V and can damage your board.

## Library Documentation

All of the `Serial[1,2,3]` objects are instances of the `HardwareSerial` class, which is documented in this section. (This means that you can use any of these functions on any of `Serial1`, `Serial2`, and `Serial3`).

class `HardwareSerial`

  Serial port class. Predefined instances are `Serial1`, `Serial2`, and `Serial3`.

`HardwareSerial::``begin`(unsigned int baud)

  Set up a `HardwareSerial` object for communications. This method must be called before attempting to use the `HardwareSerial` object (typically, you call this in your setup() function).

`HardwareSerial::``end`()

  Disables the USART associated with this object, allowing any associated communication pins to be used for other purposes.

unsigned int `HardwareSerial::``available`()

  Returns the number of bytes available for reading.

unsigned char `HardwareSerial::``read`()

  Returns the next available, unread character. If there are no available characters (you can check this with `available`), the call will block until one becomes available.

`HardwareSerial::``flush`()

  Removes the contents of the Serial’s associated USART RX FIFO. That is, clears any buffered characters, so that the next character read is guaranteed to be new.

`HardwareSerial::``print`(unsigned char b)

  Print the given byte over the USART.

`HardwareSerial::``print`(char c)

  Print the given character over the USART. 7-bit clean characters are typically interpreted as ASCII text.

`HardwareSerial::``print`(const char* str)

  Print the given null-terminated string over the USART.

`HardwareSerial::``print`(int n)

  Print the argument’s digits over the USART, in decimal format. Negative values will be prefixed with a `'-'` character.

`HardwareSerial::``print`(unsigned int n)

  Print the argument’s digits over the USART, in decimal format.

`HardwareSerial::``print`(long n)

  Print the argument’s digits over the USART, in decimal format. Negative values will be prefixed with a `'-'` character.

`HardwareSerial::``print`(unsigned long n)

  Print the argument’s digits over the USART, in decimal format.

`HardwareSerial::``print`(long n, int base)

  Print the digits of `n` over the USART, in base `base` (which may be between 2 and 16). The `base` value 2 corresponds to binary, 8 to octal, 10 to decimal, and 16 to hexadecimal. Negative values will be prefixed with a `'-'` character.

`HardwareSerial::``print`(double n)

  Print `n`, accurate to 2 digits after the decimal point.

`HardwareSerial::``println`(char c)

  Like `print(c)`, followed by `"\r\n"`.

`HardwareSerial::``println`(const char* c)

  Like `print(c)`, followed by `"\r\n"`.

`HardwareSerial::``println`(unsigned char b)

  Like `print(b)`, followed by `"\r\n"`.

`HardwareSerial::``println`(int n)

  Like `print(n)`, followed by `"\r\n"`.

`HardwareSerial::``println`(unsigned int n)

  Like `print(n)`, followed by `"\r\n"`.

`HardwareSerial::``println`(long n)

  Like `print(n)`, followed by `"\r\n"`.

`HardwareSerial::``println`(unsigned long n)

  Like `print(n)`, followed by `"\r\n"`.

`HardwareSerial::``println`(long n, int base)

  Like `print(n, b)`, followed by `"\r\n"`.

`HardwareSerial::``println`(double n)

  Like `print(n)`, followed by `"\r\n"`.

`HardwareSerial::``println`()

  Prints `"\r\n"` over the USART.

`HardwareSerial::``write`(unsigned char ch)

  Sends one character over the USART. This function is currently blocking, although nonblocking writes are a planned future extension.

  This is a low-level function. One of the `print()` or `println()` functions is likely to be more useful when printing multiple characters, when formatting numbers for printing, etc.

`HardwareSerial::``write`(const char* str)

  Send the given null-terminated character string over the USART.

  This is a low-level function. One of the `print()` or `println()` functions is likely to be more useful when printing multiple characters, when formatting numbers for printing, etc.

`HardwareSerial::``write`(void* buf, unsigned int size)

  Writes the first `size` bytes of `buf` over the USART. Each byte is transmitted as an individual character.

  This is a low-level function. One of the `print()` or `println()` functions is likely to be more useful when printing multiple characters, when formatting numbers for printing, etc.

## Arduino Compatibility Note

Unlike the Arduino, none of the Maple’s serial ports is connected to the USB port on the Maple board (for that, use SerialUSB). Thus, to use these pins to communicate with your personal computer, you will need an additional USB-to-serial adaptor.

License and Attribution

This documentation page was adapted from the Arduino Reference Documentation, which is released under a Creative Commons Attribution-ShareAlike 3.0 License.

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