So far I have been blindly copying an example of the Wiring Pi gpio utiliy and know almost nothing of how to use it with other commands. Now I am reading the manual page to learn more about it.
GPIO(21st October 2012)
NAME
gpio - Command-line access to Raspberry Pi and PiFace GPIO
SYNOPSIS
gpio -v
gpio [ -g ] read/write/wb/pwm/clock/mode ...
gpio [ -p ] read/write/wb ...
gpio readall
gpio unexportall/exports
gpio export/edge/unexport ...
gpio drive group value
gpio pwm-bal/pwm-ms
gpio pwmr range
gpio load i2c/spi ...
gpio gbr channel
gpio gbw channel value
DESCRIPTION
GPIO is a swiss army knife of a command line tool to allow the user
easy access to the GPIO pins on the Raspberry Pi and the SPI A/D and
D/A converters on the Gertboard. It's designed for simple testing and
diagnostic purposes, but can be used in shell scripts for general if
somewhat slow control of the GPIO pins.
It can also control the IO's on the PiFace IO board and load the SPI
and I2C kernel modules if required.
Additionally, it can be used to set the exports in the /sys/class/gpio
system directory to allow subsequent programs to use the
/sys/class/gpio interface without needing to be run as root.
OPTIONS
-v Output the current version including the board revision of the
Raspberry Pi.
-g Use the BCM_GPIO pins numbers rather than wiringPi pin numbers.
NOTE: The BCM_GPIO pin numbers are always used with the export
and edge commands.
-p Use the PiFace interface board and its corresponding pin num??
bers.
read <pin>
Read the digital value of the given pin and print 0 or 1 to rep??
resent the respective logic levels.
write <pin> <value>
Write the given value (0 or 1) to the pin. You need to set the
pin to output mode first.
wb <value>
Write the given byte to the 8 main GPIO pins. You can prefix it
with 0x to specify a hexadecimal number. You need to set pins to
output mode first.
readall
Output a table of all GPIO pins values. The values represent the
actual values read if the pin is in input mode, or the last
value written if the pin is in output mode.
pwm <pin> <value>
Write a PWM value (0-1023) to the given pin. The pin needs to be
put into PWM mode first.
clock <pin> <frequency>
Set the output frequency on the given pin. The pin needs to be
put into clock mode first.
mode <pin> <mode>
Set a pin into input, output or pwm mode. Can also use the lit??
erals up, down or tri to set the internal pull-up, pull-down or
tristate (off) controls.
unexportall
Un-Export all the GPIO pins in the /sys/class/gpio directory.
exports
Print a list (if any) of all the exported GPIO pins and their
current values.
export Export a GPIO pin in the /sys/class/gpio directory. Use like the
mode command above however only in and out are supported at this
time. Note that the pin number is the BCM_GPIO number and not
the wiringPi number.
Once a GPIO pin has been exported, the gpio program changes the
ownership of the /sys/class/gpio/gpioX/value and if present in
later kernels, the /sys/class/gpio/gpioX/edge pseudo files to
that of the user running the gpio program. This means that you
can have a small script of gpio exports to setup the gpio pins
as your program requires without the need to run anything as
root, or with the sudo command.
edge This exports a GPIO pin in the /sys/class/gpio directory, set
the direction to input and set the edge interrupt method to
none, rising, falling or both. Use like the export command
above and note that BCM_GPIO pin number is used not not wiringPi
pin numbering.
Like the export commands above, ownership is set to that of the
calling user, allowing subsequent access from user programs
without requiring root/sudo.
unexport
Un-Export a GPIO pin in the /sys/class/gpio directory.
drive group value
Change the pad driver value for the given pad group to the sup??
plied drive value. Group is 0, 1 or 2 and value is 0-7. Do not
use unless you are absolutely sure you know what you're doing.
pwm-bal/pwm-ms
Change the PWM mode to balanced (the default) or mark:space
ratio (traditional)
pwmr Change the PWM range register. The default is 1024.
load i2c [baudrate]
This loads the i2c or drivers into the kernel and changes the
permissions on the associated /dev/ entries so that the current
user has access to them. Optionally it will set the I2C baudrate
to that supplied (or as close as the Pi can manage) The default
speed is 100Kb/sec.
load spi [buffer size in KB]
This loads the spi drivers into the kernel and changes the per??
missions on the associated /dev/ entries so that the current
user has access to them. Optionally it will set the SPI buffer
size to that supplied. The default is 4KB.
gbr channel
This reads the analog to digital converter on the Gertboard on
the given channel. The board jumpers need to be in-place to do
this operation.
gbw channel value
This writes the supplied value to the output channel on the
Gertboards SPI digital to analogue converter. The board jumpers
need to be in-place to do this operation.
WiringPi vs. BCM_GPIO Pin numbering
WiringPi GPIO-r1 GPIO-r2 Function
?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€?€
0 17 17
1 18 18 (PWM)
2 21 27
3 22 22
4 23 23
5 24 24
6 25 25
7 4 4
8 0 2 I2C: SDA0
9 1 3 I2C: SCL0
10 8 8 SPI: CE0
11 7 7 SPI: CE1
12 10 10 SPI: MOSI
13 9 9 SPI: MISO
14 11 11 SPI: SCLK
15 14 14 TxD
16 15 16 RxD
17 - 28
18 - 29
19 - 30
20 - 31
Note that "r1" and "r2" above refers to the board revision. Normally
wiringPi detects the correct board revision with use for it's own num??
bering scheme, but if you are using a Revision 2 board with some of the
pins which change numbers between revisions you will need to alter your
software.
FILES
gpio executable
EXAMPLES
gpio mode 4 output # Set pin 4 to output
gpio -g mode 23 output # Set GPIO pin 23 to output (same as WiringPi
pin 4)
gpio mode 1 pwm # Set pin 1 to PWM mode
gpio pwm 1 512 # Set pin 1 to PWM value 512 - half brightness
gpio export 17 out # Set GPIO Pin 17 to output
gpio export 0 in # Set GPIO Pin 0 (SDA0) to input.
gpio -g read 0 # Read GPIO Pin 0 (SDA0)
NOTES
When using the export, edge or unexport commands, the pin numbers are
always native BCM_GPIO numbers and never wiringPi pin numbers.
SEE ALSO
WiringPi's home page
https://projects.drogon.net/raspberry-pi/wiringpi/
AUTHOR
Gordon Henderson
REPORTING BUGS
Please report bugs to <projects@drogon.net>
COPYRIGHT
Copyright (c) 2012 Gordon Henderson This is free software; see the
source for copying conditions. There is NO warranty; not even for MER??
CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
TRADEMARKS AND ACKNOWLEDGEMENTS
Raspberry Pi is a trademark of the Raspberry Pi Foundation. See
http://raspberrypi.org/ for full details.
Command-Line access to Raspberry Pi and PGPIO(21stOOctober 2012)
.END
No comments:
Post a Comment