NAME
WiringPi::API - API for wiringPi, providing access to the Raspberry
Pi's board, GPIO and connected peripherals
SYNOPSIS
No matter which import option you choose, before you can start making
calls, you must initialize the software by calling one of the setup*()
routines.
use WiringPi::API qw(:all)
# use as a base class with OO functionality
use parent 'WiringPi::API';
# use in the traditional Perl OO way
use WiringPi::API;
my $api = WiringPi::API->new;
DESCRIPTION
This is an XS-based module, and requires wiringPi <
http://wiringpi.com>
version 2.36+ to be installed. The wiringPiDev shared library is also
required (for the LCD functionality), but it's installed by default
with wiringPi.
See the documentation on the wiringPi <
http://wiringpi.com> website for
a more in-depth description of most of the functions it provides. Some
of the functions we've wrapped are not documented, they were just
selectively plucked from the C code itself. Each mapped function lists
which C function it is responsible for.
EXPORT_OK
Exported with the :all tag, or individually.
Perl wrapper functions for the XS functions. Not all of these are
direct wrappers; several have additional/modified functionality than
the wrapped versions, but are still 100% compatible.
setup setup_sys setup_phys setup_gpio
pull_up_down read_pin write_pin pwm_write
get_alt gpio_layout wpi_to_gpio phys_to_gpio
pwm_set_range lcd_init lcd_home lcd_clear
lcd_display lcd_cursor lcd_cursor_blink lcd_send_cmd
lcd_position lcd_char_def lcd_put_char lcd_puts
set_interrupt pin_mode analog_read analog_write
shift_reg_setup bmp180_setup bmp180_pressure bmp180_temp
ads1115_setup spi_setup spi_data phys_to_wpi
serial_open serial_flush serial_put_char serial_puts
serial_get_char serial_close serial_data_avail
EXPORT_TAGS
See EXPORT_OK
:all
Exports all available exportable functions.
FUNCTION TABLE OF CONTENTS
CORE
See "CORE FUNCTIONS".
BOARD
See "BOARD FUNCTIONS".
LCD
See "LCD FUNCTIONS".
INTERRUPT
See "INTERRUPT FUNCTIONS".
ANALOG TO DIGITAL CONVERTER
See "ADC FUNCTIONS".
SHIFT REGISTER
See "SHIFT REGISTER FUNCTIONS"
SERIAL
See "SERIAL FUNCTIONS"
I2C
See "I2C FUNCTIONS"
SPI
See "SPI FUNCTIONS"
BAROMETRIC SENSOR
See "BMP180 PRESSURE SENSOR FUNCTIONS".
CORE FUNCTIONS
new()
NOTE: After an object is created, one of the setup* methods must be
called to initialize the Pi board.
Returns a new WiringPi::API object.
setup()
Maps to int wiringPiSetup()
Sets the pin number mapping scheme to wiringPi.
See pinout.xyz <
https://pinout.xyz/pinout/wiringpi> for a pin number
conversion chart, or on the command line, run gpio readall.
Note that only one of the setup*() methods should be called per program
run.
setup_gpio()
Maps to int wiringPiSetupGpio()
Sets the pin numbering scheme to GPIO.
Personally, this is the setup routine that I always use, due to the
GPIO numbers physically printed right on the Pi board.
setup_phys()
Maps to int wiringPiSetupPhys()
Sets the pin mapping to use the physical pin position number on the
board.
setup_sys()
Maps to int wiringPiSetupSys()
DEPRECATED.
This function is here for legacy purposes only, to provide non-root
user access to the GPIO. It required exporting the pins manually before
use. wiringPi now uses /dev/gpiomem by default, which does not require
root level access.
Sets the pin numbering scheme to GPIO.
pin_mode($pin, $mode)
Maps to void pinMode(int pin, int mode)
Puts the pin in either INPUT, OUTPUT, PWM or GPIO_CLOCK mode.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$mode
Mandatory: 0 for INPUT, 1 OUTPUT, 2 PWM_OUTPUT and 3 GPIO_CLOCK.
pin_mode_alt($pin, $alt)
Maps to the undocumented void pinModeAlt(int pin, int mode)
Allows you to set any pin to any mode. ALT modes allowed:
value mode
------------
0 INPUT
1 OUTPUT
4 ALT0
5 ALT1
6 ALT2
7 ALT3
3 ALT4
2 ALT5
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$alt
Mandatory, Integer: The mode you want to put the pin into. See the list
above for the relevant values for this parameter.
read_pin($pin);
Maps to int digitalRead(int pin)
Returns the current state (HIGH/on, LOW/off) of a given pin.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
write_pin($pin, $state)
Maps to void digitalWrite(int pin, int state)
Sets the state (HIGH/on, LOW/off) of a given pin.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$state
Mandatory: 1 to turn the pin on (HIGH), and 0 to turn it LOW (off).
analog_read($pin);
Maps to int analogRead(int pin)
Returns the data for an analog pin. Note that the Raspberry Pi doesn't
have analog pins, so this is used when connected through an ADC or to
pseudo analog pins.
Parameters:
$pin
Mandatory: The pseudo pin number, in the pin numbering scheme dictated
by whichever setup*() routine you used.
analog_write($pin, $value)
Maps to void analogWrite(int pin, int value)
Writes the value to the corresponding analog pseudo pin.
Parameters:
$pin
Mandatory: The pseudo pin number, in the pin numbering scheme dictated
by whichever setup*() routine you used.
$value
Mandatory: The data which you want to write to the pseudo pin.
pull_up_down($pin, $direction)
Maps to void pullUpDnControl(int pin, int pud)
Enable/disable the built-in pull up/down resistors for a specified pin.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$direction
Mandatory: 2 for UP, 1 for DOWN and 0 to disable the resistor.
pwm_write($pin, $value)
Maps to void pwmWrite(int pin, int value)
Sets the Pulse Width Modulation duty cycle (on-time) of the pin.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$value
Mandatory: 0 to 1023. 0 is 0% (off) and 1023 is 100% (fully on).
get_alt($pin)
Maps to int getAlt(int pin)
This returns the current mode of the pin (using getAlt() C call). Modes
are INPUT 0, OUTPUT 1, PWM_OUT 2 and CLOCK 3.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
BOARD FUNCTIONS
gpio_layout()
Maps to int piGpioLayout()
Returns the Raspberry Pi board's GPIO layout (ie. the board revision).
wpi_to_gpio($pin_num)
Maps to int wpiPinToGpio(int pin)
Converts a wiringPi pin number to the Broadcom (GPIO) representation,
and returns it.
Parameters:
$pin_num
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
phys_to_gpio($pin_num)
Maps to int physPinToGpio(int pin)
Converts the pin number on the physical board to the GPIO
representation, and returns it.
Parameters:
$pin_num
Mandatory: The pin number on the physical Raspberry Pi board.
phys_to_wpi($pin_num)
Maps to int physPinToWpi(int pin)
Converts the pin number on the physical board to the wiringPi numbering
representation, and returns it.
Parameters:
$pin_num
Mandatory: The pin number on the physical Raspberry Pi board.
pwm_set_range($range);
Maps to void pwmSetRange(int range)
Sets the range register of the Pulse Width Modulation (PWM)
functionality. It defaults to 1024 (0-1023).
Parameters:
$range
Mandatory: An integer between 0 and 1023.
LCD FUNCTIONS
There are several methods to drive standard Liquid Crystal Displays.
See wiringPiDev LCD page <
http://wiringpi.com/dev-lib/lcd-library/> for
full details.
lcd_init(%args)
Maps to:
int lcdInit(
rows, cols, bits, rs, strb,
d0, d1, d2, d3, d4, d5, d6, d7
);
Initializes the LCD library, and returns an integer representing the
handle (file descriptor) of the device.
Parameters:
%args = (
rows => $num, # number of rows. eg: 2 or 4
cols => $num, # number of columns. eg: 16 or 20
bits => 4|8, # width of the interface (4 or 8)
rs => $pin_num, # pin number of the LCD's RS pin
strb => $pin_num, # pin number of the LCD's strobe (E) pin
d0 => $pin_num, # pin number for LCD data pin 1
...
d7 => $pin_num, # pin number for LCD data pin 8
);
Mandatory: All entries must have a value. If you're only using four (4)
bit width, d4 through d7 must be set to 0.
Note: When in 4-bit mode, the d0 through 3 parameters actually map to
pins d4 through d7 on the LCD board, so you need to connect those pins
to their respective selected GPIO pins.
NOTE: There is an upper limit of the number of LCDs that can be
initialized simultaneously. This number is 8 (0-7). Always check the
return of this function to ensure you're under the maximum file
descriptors. If you receive a `-1`, you're out of bounds, and any
functions called on the LCD will cause a segmentation fault.
lcd_home($fd)
Maps to void lcdHome(int fd)
Moves the LCD cursor to the home position (top row, leftmost column).
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
lcd_clear($fd)
Maps to void lcdClear(int fd)
Clears the LCD display.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
lcd_display($fd, $state)
Maps to void lcdDisplay(int fd, int state)
Turns the LCD display on and off.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$state
Mandatory: 0 to turn the display off, and 1 for on.
lcd_cursor($fd, $state)
Maps to void lcdCursor(int fd, int state)
Turns the LCD cursor on and off.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$state
Mandatory: 0 to turn the cursor off, 1 for on.
lcd_cursor_blink($fd, $state)
Maps to void lcdCursorBlink(int fd, int state)
Allows you to enable/disable a blinking cursor.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$state
Mandatory: 0 to turn the cursor blink off, 1 for on. Default is off
(0).
lcd_send_cmd($fd, $command)
Maps to void lcdSendCommand(int fd, char command)
Sends any arbitrary command to the LCD.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$command
Mandatory: A command to submit to the LCD.
lcd_position($fd, $x, $y)
Maps to void lcdPosition(int fd, int x, int y)
Moves the cursor to the specified position on the LCD display.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$x
Mandatory: Column position. 0 is the left-most edge.
$y
Mandatory: Row position. 0 is the top row.
lcd_char_def($fd, $index, $data)
Maps to void lcdCharDef(int fd, unsigned char data [8]). This function
is
This allows you to re-define one of the 8 user-definable characters in
the display.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$index
Mandatory: Index of the display character. Values are 0-7. Once the
char is stored at this index, it can be used at any time with the
lcd_put_char() function.
$data
Mandatory: Array reference of exactly 8 elements. Each element is a
single unsigned char byte. These bytes represent the character from the
top-line to the bottom line.
Note that the characters are actually 5 x 8, so only the lower 5 bits
are of each element are used (ie. `0b11111` or 0b00011111`). The index
is from 0 to 7 and you can subsequently print the character defined
using the lcdPutchar() call using the same index sent in to this
function.
lcd_put_char($fd, $char)
Maps to void lcdPutChar(int fd, unsigned char data)
Writes a single ASCII character to the LCD display, at the current
cursor position.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$char
Mandatory: The character byte to print to the LCD. Note that 0-7 are
reserved for custom characters, as defined with lcd_char_def(). To
print one of your custom chars, $char should be the same integer of the
$index you used to store it in that function.
lcd_puts($fd, $string)
Maps to void lcdPuts(int fd, char *string)
Writes a string to the LCD display, at the current cursor position.
Parameters:
$fd
Mandatory: The file descriptor integer returned by lcd_init().
$string
Mandatory: A string to display.
INTERRUPT FUNCTIONS
set_interrupt($pin, $edge, $callback)
IMPORTANT: The interrupt functionality requires that your Perl can be
used in pthreads. If you do not have a threaded Perl, the program will
cause a segmentation fault.
Wrapper around wiringPi's wiringPiISR() that allows you to send in the
name of a Perl sub in your own code that will be called if an interrupt
is triggered.
Parameters:
$pin
Mandatory: The pin number, in the pin numbering scheme dictated by
whichever setup*() routine you used.
$edge
Mandatory: 1 (lowering), 2 (raising) or 3 (both).
$callback
Mandatory: The string name of a subroutine previously written in your
user code that will be called when the interrupt is triggered. This is
your interrupt handler.
ADC FUNCTIONS
Analog to digital converters (ADC) allow you to read analog data on the
Raspberry Pi, as the Pi doesn't have any analog input pins.
This section is broken down by type/model.
ADS1115 MODEL
ads1115_setup($pin_base, $addr)
Maps to `ads1115Setup(int pinBase, int addr)`.
The ADS1115 is a four channel, 16-bit wide ADC.
Parameters:
$pin_base
Mandatory: Signed integer, higher than that of all GPIO pins. This is
the base number we'll use to access the pseudo pins on the ADC.
Example: If 400 is sent in, ADC pin A0 (or 0) will be pin 400, and AD3
(the fourth analog pin) will be 403.
Parameters:
$addr
Mandatory: Signed integer. This parameter depends on how you have the
ADDR pin on the ADC connected to the Pi. Below is a chart showing if
the ADDR pin is connected to the Pi Pin, you'll get the address. You
can also use i2cdetect -y 1 to find out your ADC address.
Pin Address
---------------
Gnd 0x48
VDD 0x49
SDA 0x4A
SCL 0x4B
SHIFT REGISTER FUNCTIONS
Shift registers allow you to add extra output pins by multiplexing a
small number of GPIO.
Currently, we support the SR74HC595 unit, which provides eight outputs
by using only three GPIO. To further, this particular unit can be daisy
chained up to four wide to provide an additional 32 outputs using the
same three GPIO pins.
shift_reg_setup
This function configures the Raspberry Pi to use a shift register (The
SR74HC595 is currently supported).
Parameters:
$pin_base
Mandatory: Signed integer, higher than that of all existing GPIO pins.
This parameter registers pin 0 on the shift register to an internal
GPIO pin number. For example, setting this to 100, you will be able to
access the first output on the register as GPIO 100 in all other
functions.
$num_pins
Mandatory: Signed integer, the number of outputs on the shift register.
For a single SR74HC595, this is eight. If you were to daisy chain two
together, this parameter would be 16.
$data_pin
Mandatory: Integer, the GPIO pin number connected to the register's DS
pin (14). Can be any GPIO pin capable of output.
$clock_pin
Mandatory: Integer, the GPIO pin number connected to the register's
SHCP pin (11). Can be any GPIO pin capable of output.
$latch_pin
Mandatory: Integer, the GPIO pin number connected to the register's
STCP pin (12). Can be any GPIO pin capable of output.
SERIAL FUNCTIONS
These functions provide basic access to read and write to a serial
device.
serial_open($device, $baud)
Maps to int serialOpen(const char *device, const int baud)
Opens a serial device for read/write access.
Parameters:
$device
Mandatory, String: The name of the serial device, eg: /dev/ttyACM0.
$baud
Mandatory, Integer: The speed of the serial device. (eg: 9600).
Return, Integer: The file descriptor of the device.
serial_close($fd)
Maps to void serialClose(const int fd)
Closes an already open serial device.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
serial_flush($fd)
Maps to serialFlush(const int fd)
Flushes the serial device's buffer.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
serial_data_avail($fd)
Maps to serialDataAvail(const int fd)
Check if there is any data available on the serial interface.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
serial_get_char($fd)
Maps to serialGetchar(const int fd)
Read a single byte from the serial interface.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
serial_put_char($fd, $char)
Maps to serialPutchar(const int fd, const unsigned char c)
Write a single byte to the interface.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
$char
Mandatory, Byte: A single byte to write to the serial interface.
serial_puts($fd, $string)
Maps to serialPuts(const int fd, const char* string)
Write an arbitrary length string to the serial interface.
Parameters:
$fd
Mandatory, Integer: The file descriptor returned by your call to
serial_open().
$string
Mandatory, String: The content to write to the device.
I2C FUNCTIONS
These functions allow you to read and write devices on the
Inter-Integrated Circuit (I2C) bus.
i2c_setup($addr)
Maps to int wiringPiI2CSetup(int devId)
Configures the I2C bus in preparation for communicating with a device.
Parameters:
$addr
Mandatory: Integer, the address of your device as seen by running for
example: i2cdetect -y 1.
i2c_interface($device, $addr)
Maps to iint wiringPiI2CSetupInterface(const char* device, int devId)
This feature is not implemented currently, and will be used to select
different I2C interfaces if the RPi ever receives them.
i2c_read($fd)
Performs a quick one-off, one-byte read without needing to specify the
register value. Some very simple devices operate without register
values needed.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
Returns: A single byte of data from the device on the I2C bus.
i2c_read_byte($fd, $reg)
Reads a single byte from the specified register.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
$reg
Mandatory: Integer, the register to read data from.
Returns: A single byte of data from the device on the I2C bus from the
selected register.
i2c_read_word($fd, $reg)
Reads two bytes from the specified register.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
$reg
Mandatory: Integer, the register to read data from.
Returns: Integer, two bytes of data from the device on the I2C bus from
the selected register.
i2c_write($fd, $data)
Performs a quick one-off, one-byte write without needing to specify the
register value. Some very simple devices operate without register
values needed.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
$data
Mandatory: Integer, the value to write to the device.
Returns: The value of the ioctl() call, 0 on success.
i2c_write_byte($fd, $reg, $data)
Writes a single byte to the register specified.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
$reg
Mandatory: Integer, the register to write the data to.
$data
Mandatory: Integer, the value to write to the device.
Returns: The value of the ioctl() call, 0 on success.
i2c_write_word($fd, $reg, $data)
Writes two bytes to the register specified.
Parameters:
$fd
Mandatory: Integer, the file descriptor that was returned from
i2c_setup().
$reg
Mandatory: Integer, the register to write the data to.
$data
Mandatory: Integer, the value to write to the device.
Returns: The value of the ioctl() call, 0 on success.
SPI FUNCTIONS
These functions allow you to set up and read/write to devices on the
serial peripheral interface (SPI) bus.
spi_setup
Maps to int wiringPiSPISetup(int channel, int speed)
Configure the SPI bus for use to communicate with its connected
devices.
Parameters:
$channel
Mandatory: Integer, the SPI channel the device is connected to. 0 for
channel /dev/spidev0.0 and 1 for channel /dev/spidev0.1.
$speed
Optional: Integer, the speed for SPI communication. Defaults to 1000000
(1MHz).
Note that it's wise to do some error checking when attempting to open
the SPI bus. We return the return value of an ioctl() call, so this
does the trick:
if ((spi_setup(0, 1000000) < 0){
die "failed to open the SPI bus...\n";
}
spi_data
Maps to: int spiDataRW(int channel, AV* data, int len), which calls int
wiringPiSPIDataRW(int channel, unsigned char* data, int len).
Writes, and then reads a block of data over the SPI bus. The read
following the write is read into the transmit buffer, so it'll be
overwritten and sent back as a Perl array.
Parameters:
$channel
Mandatory: Integer, the SPI channel the device is connected to. 0 for
channel /dev/spidev0.0 and 1 for channel /dev/spidev0.1.
$data
Mandatory: An array reference, with each element containing a single
unsigned 8-bit byte that you want to write to the device. If you want
to read-only, send in an aref with all the elements set to 0. These
will be overwritten with the read data, and sent back as a Perl array.
$len
Mandatory: Integer, the number of bytes contained in the $data
parameter array reference that will be sent to the device. I could just
count the number of elements, but this keeps things consistent, and
ensures the user is fully aware of the data they are sending on the
bus.
Returns a Perl array containing the same number of elements you sent
in.
# read-only... three bytes
my $buf = [0x00, 0x00, 0x00];
my @ret = spiDataRW($chan, $buf, 3);
BMP180 PRESSURE SENSOR FUNCTIONS
These functions configure and fetch data from the BMP180 barometric
pressure sensor.
bmp180_setup($pin_base)
Configures the system to read from a BMP180 pressure sensor.
These functions can not return the raw values from the sensor. See each
function documentation to learn how to do so.
Parameters:
$pin_base
Mandatory: Integer, the number at which to place the pseudo analog pins
in the GPIO stack. For example, if you use 200, pin 200 represents the
temperature feature of the sensor, and 201 represents the pressure
feature.
Return: undef.
bmp180_temp($pin, $want)
Returns the temperature from the sensor.
Parameters:
$pin
Mandatory: Integer, represents the $pin_base used in the setup function
+ 0.
$want
Optional: 'c' for Celcius, and 'f' for Farenheit. Defaults to 'f'.
Return: A floating point number in the requested conversion.
NOTE: To get the raw sensor temperature, call the C function
bmp180Temp($pin) directly.
bmp180_pressure($pin)
Returns the current air pressure in kPa.
Parameters:
$pin
Mandatory: Integer, represents the $pin_base used in the setup function
+ 1.
Return: A floating point number that represents the air pressure in
kPa.
NOTE: To get the raw sensor pressure, call the C function
bmp180Pressure($pin) directly.
DEVELOPER FUNCTIONS
These functions are under testing, or don't potentially have a use to
the end user. They may be risky to use, so use at your own risk.
The functions in this section do not have a Perl wrapper equivalent.
pseudoPinsSetup(int pinBase)
This function allocates shared memory for the pseudo pins used to
communicate with devices that are beyond the reach of the Pi's GPIO
(eg: shift registers, ADCs etc).
Parameters:
pinBase
Mandatory: Integer, larger than the highest GPIO pin number. Eg: 500
will be the base for the analog pins on an ADS1115 ADC. Pin A0 would be
500, and ADC pin A3 would be 503.
pinModeAlt(int pin, int mode)
Undocumented function that allows any pin to be set to any mode.
Parameters:
pin
Mandatory: Signed integer, any valid GPIO pin number.
mode
Mandatory: Signed integer, any valid wiringPi pin mode.
digitalWriteByte(const int value)
Writes an 8-bit byte to the first eight GPIO pins.
Parameters:
value
Mandatory: Unsigned int, the byte value you want to send in.
Return: void
digitalWriteByte2(const int value)
Same as "digitalWriteByte(const int value)", but writes to the second
group of eight GPIO pins.
digitalReadByte()
Reads an 8-bit byte from the first eight GPIO pins on the Pi.
Takes no parameters, returns the byte value as an unsigned int.
digitalReadByte2()
Same as "digitalReadByte", but reads from the second group of eight
GPIO pins.
AUTHOR
Steve Bertrand, <
[email protected]>
COPYRIGHT AND LICENSE
Copyright (C) 2017 by Steve Bertrand
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.18.2 or, at
your option, any later version of Perl 5 you may have available.
