WiringPi::API - Direct access to Raspberry Pi's wiringPi API, with optional Perl OO access
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.
setup*()
# import the API functions directly use WiringPi::API qw(:wiringPi) # import the Perl wrapped functions use WiringPi::API qw(:perl) # import both versions 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;
This is an XS-based module, and requires wiringPi to be installed. The wiringPiDev shared library is also required (for the LCD functionality), but it's installed by default with wiringPi.
wiringPiDev
wiringPi
This module allows you to import the wiringPi's functions directly as-is, use it as a Perl base class, export the Perl wrapped functions, or use it in a traditional Perl OO way.
See the documentation on the wiringPi 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.
Exported with the :wiringPi tag.
:wiringPi
These XS functions map directly to the wiringPi functions with their original names. Note that setInterrupt is not a direct wrapper, it's a custom C wrapper for wiringPiISR() in order to make it functional here.
setInterrupt
wiringPiISR()
wiringPiSetup wiringPiSetupSys wiringPiSetupGpio wiringPiSetupPhys pinMode pullUpDnControl digitalRead digitalWrite digitalWriteByte pwmWrite getAlt piBoardDev wpiToGpio physPinToGpio pwmSetRange lcdInit lcdHome lcdClear lcdDisplay lcdCursor lcdCursorBlink lcdSendCommand lcdPosition lcdCharDef lcdPutChar lcdPuts setInterrupt softPwmCreate softPwmWrite softPwmStop
Exported with the :perl tag.
:perl
Perl wrapper functions for the XS functions.
setup setup_sys setup_phys setup_gpio pin_mode pull_up_down read_pin write_pin pwm_write get_alt board_rev 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 soft_pwm_create soft_pwm_write soft_pwm_stop
See EXPORT_OK
Exports all available exportable functions.
NOTE: After an object is created, one of the setup* methods must be called to initialize the Pi board.
setup*
Returns a new WiringPi::API object.
WiringPi::API
Maps to int wiringPiSetup()
int wiringPiSetup()
Sets the pin number mapping scheme to wiringPi.
This setup routine requires you to run your script as the root user.
root
Each setup function has benefits and drawbacks. Please refer to the wiringPi setup functions for details.
See pinout.xyz for a pin number conversion chart, or on the command line, run gpio readall.
gpio readall
Note that only one of the setup*() methods can be called per program run.
Maps to int wiringPiSetupSys()
int wiringPiSetupSys()
Sets the pin numbering scheme to GPIO.
GPIO
This setup routine does NOT require running as root, but you have to manually export the pins yourself with the gpio command line utility prior to using the pins.
gpio
Maps to int wiringPiSetupPhys()
int wiringPiSetupPhys()
Sets the pin mapping to use the physical pin position number on the board.
Maps to int wiringPiSetupGpio()
int wiringPiSetupGpio()
Maps to void pinMode(int pin, int mode)
void pinMode(int pin, int mode)
Puts the pin in either INPUT or OUTPUT 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.
0
1
2
3
Maps to int digitalRead(int pin)
int digitalRead(int pin)
Returns the current state (HIGH/on, LOW/off) of a given pin.
Maps to void digitalWrite(int pin)
void digitalWrite(int pin)
Sets the state (HIGH/on, LOW/off) of a given pin.
$state
Mandatory: 1 to turn the pin on (HIGH), and 0 to turn it LOW (off).
Maps to void pullUpDnControl(int pin, int pud)
void pullUpDnControl(int pin, int pud)
Enable/disable the built-in pull up/down resistors for a specified pin.
$direction
Mandatory: 2 for UP, 1 for DOWN and 0 to disable the resistor.
Maps to void pwmWrite(int pin, int value)
void pwmWrite(int pin, int value)
Sets the Pulse Width Modulation duty cycle (on-time) of the pin.
$value
Mandatory: 0 to 1023. 0 is 0% (off) and 1023 is 100% (fully on).
1023
Maps to int getAlt(int pin)
int getAlt(int pin)
This returns the current mode of the pin (using getAlt() C call). Modes are INPUT 0, OUTPUT 1, PWM 2 and CLOCK 3.
getAlt()
Maps to int piBoardRev()
int piBoardRev()
Returns the Raspberry Pi board's revision.
Maps to int wpiPinToGpio(int pin)
int wpiPinToGpio(int pin)
Converts a wiringPi pin number to the Broadcom (BCM) representation, and returns it.
$pin_num
Maps to int physPinToGpio(int pin)
int physPinToGpio(int pin)
Converts the pin number on the physical board to the GPIO representation, and returns it.
Mandatory: The pin number on the physical Raspberry Pi board.
Maps to int physPinToWpi(int pin)
int physPinToWpi(int pin)
Converts the pin number on the physical board to the wiringPi numbering representation, and returns it.
Maps to void pwmSetRange(int range)
void pwmSetRange(int range)
Sets the range register of the Pulse Width Modulation (PWM) functionality. It defaults to 1024 (0-1023).
1024
0-1023
$range
Mandatory: An integer between 0 and 1023.
There are several methods to drive standard Liquid Crystal Displays. See wiringPiDev LCD page for full details.
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 handle (file descriptor) of the device. The return is supposed to be constant, so DON'T change it.
%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.
d4
d7
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.
d0
Maps to void lcdHome(int fd)
void lcdHome(int fd)
Moves the LCD cursor to the home position (top row, leftmost column).
$fd
Mandatory: The file descriptor integer returned by lcd_init().
lcd_init()
Maps to void lcdClear(int fd)
void lcdClear(int fd)
Clears the LCD display.
Maps to void lcdDisplay(int fd, int state)
void lcdDisplay(int fd, int state)
Turns the LCD display on and off.
Mandatory: 0 to turn the display off, and 1 for on.
Maps to void lcdCursor(int fd, int state)
void lcdCursor(int fd, int state)
Turns the LCD cursor on and off.
Mandatory: 0 to turn the cursor off, 1 for on.
Maps to void lcdCursorBlink(int fd, int state)
void lcdCursorBlink(int fd, int state)
Allows you to enable/disable a blinking cursor.
Maps to void lcdSendCommand(int fd, char command)
void lcdSendCommand(int fd, char command)
Sends any arbitrary command to the LCD.
$command
Mandatory: A command to submit to the LCD.
Maps to void lcdPosition(int fd, int x, int y)
void lcdPosition(int fd, int x, int y)
Moves the cursor to the specified position on the LCD display.
$x
Mandatory: Column position. 0 is the left-most edge.
$y
Mandatory: Row position. 0 is the top row.
Maps to void lcdCharDef(int fd, unsigned char data [8])
void lcdCharDef(int fd, unsigned char data [8])
This allows you to re-define one of the 8 user-definable characters in the display. The data array is 8 bytes which represent the character from the top-line to the bottom line. Note that the characters are actually 5×8, so only the lower 5 bits are used. The index is from 0 to 7 and you can subsequently print the character defined using the lcdPutchar() call.
$index
Mandatory: Index of the display character. Values are 0-7.
0-7
$data
Mandatory: See above description.
Maps to void lcdPutChar(int fd, unsigned char data)
void lcdPutChar(int fd, unsigned char data)
Writes a single ASCII character to the LCD display, at the current cursor position.
$char
Mandatory: A single ASCII character.
Maps to void lcdPuts(int fd, char *string)
void lcdPuts(int fd, char *string)
Writes a string to the LCD display, at the current cursor position.
$string
Mandatory: A string to display.
Software Pulse Width Modulation is not the same as hardware PWM. It should not be used for critical things as it's frequency isn't 100% stable.
This software PWM allows you to use PWM on ANY GPIO pin, not just the single hardware pin available.
Creates a new software PWM thread that runs outside of your main application.
$initial_value
Optional: A value between 0 and $range.
Optional: Look at this like a dial. We start at 0 and the dial has turned completely when we hit the $range integer. If not sent in, defaults to 1023.
Sets the HIGH frequency on pin to whatever is in $value. The value must be lower than what was set in the $range parameter to soft_pwm_create().
HIGH
pin
soft_pwm_create()
Turns off software PWM on the $pin.
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.
$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.
head1 AUTHOR
Steve Bertrand, <steveb@cpan.org>
Copyright (C) 2016 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.
1 POD Error
The following errors were encountered while parsing the POD:
Non-ASCII character seen before =encoding in '5×8,'. Assuming UTF-8
To install WiringPi::API, copy and paste the appropriate command in to your terminal.
cpanm
cpanm WiringPi::API
CPAN shell
perl -MCPAN -e shell install WiringPi::API
For more information on module installation, please visit the detailed CPAN module installation guide.