Recent changes to BasicUsage

Discussion for BasicUsage page

glenneroo — Thu, 31 May 2018 18:14:34 -0000

For Asus Tinker Board's, RPI_INFO is ASUSPI_INFO.

BasicUsage modified by Ben Croston

Ben Croston — Fri, 01 Jan 2016 16:18:31 -0000

--- v8
+++ v9
@@ -35,7 +35,7 @@
     :::python
     mode = GPIO.getmode()

-The mode will be GPIO.BOARD, GPIO.BCM or GPIO.UNKNOWN
+The mode will be GPIO.BOARD, GPIO.BCM or None

 ## Warnings

BasicUsage modified by Ben Croston

Ben Croston — Sun, 15 Feb 2015 22:41:41 -0000

--- v7
+++ v8
@@ -29,6 +29,13 @@
     GPIO.setmode(GPIO.BOARD)
       # or
     GPIO.setmode(GPIO.BCM)
+
+To detect which pin numbering system has been set (for example, by another Python module):
+
+    :::python
+    mode = GPIO.getmode()
+
+The mode will be GPIO.BOARD, GPIO.BCM or GPIO.UNKNOWN

 ## Warnings

@@ -101,7 +108,7 @@

 ## Cleanup

-At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs with no pull up/down, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used. 
+At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs with no pull up/down, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used.  Note that GPIO.cleanup() also clears the pin numbering system in use.

 To clean up at the end of your script:

BasicUsage modified by Ben Croston

Ben Croston — Thu, 12 Feb 2015 03:07:23 -0000

--- v6
+++ v7
@@ -115,11 +115,16 @@
     GPIO.cleanup( (channel1, channel2) )
     GPIO.cleanup( [channel1, channel2] )

-## RPi Board Revision and RPi.GPIO version
+## RPi Board Information and RPi.GPIO version

-To discover the Raspberry Pi board revision: 
-    
-    GPIO.RPI_REVISION
+To discover information about your RPi:
+
+    GPIO.RPI_INFO
+
+To discover the Raspberry Pi board revision:
+
+    GPIO.RPI_INFO['P1_REVISION']
+    GPIO.RPI_REVISION    (deprecated)

 To discover the version of RPi.GPIO:

BasicUsage modified by Ben Croston

Ben Croston — Sun, 04 Jan 2015 21:27:46 -0000

--- v5
+++ v6
@@ -108,10 +108,12 @@
     :::python
     GPIO.cleanup()

-It is possible that you only want to clean up one channel, leaving some set up when your program exits:
+It is possible that don't want to clean up every channel leaving some set up when your program exits.  You can clean up individual channels, a list or a tuple of channels:

     :::python
     GPIO.cleanup(channel)
+    GPIO.cleanup( (channel1, channel2) )
+    GPIO.cleanup( [channel1, channel2] )

 ## RPi Board Revision and RPi.GPIO version

BasicUsage modified by Ben Croston

Ben Croston — Tue, 11 Nov 2014 13:17:04 -0000

--- v4
+++ v5
@@ -60,6 +60,16 @@
     :::python
     GPIO.setup(channel, GPIO.OUT, initial=GPIO.HIGH)

+## Setup more than one channel
+
+You can set up more than one channel per call (release 0.5.8 onwards).  For example:
+
+    :::python
+    chan_list = [11,12]    # add as many channels as you want!
+                           # you can tuples instead i.e.:
+                           #   chan_list = (11,12)
+    GPIO.setup(chan_list, GPIO.OUT)
+
 ## Input

 To read the value of a GPIO pin:
@@ -79,6 +89,15 @@
 (where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). 

 State can be 0 / GPIO.LOW / False or 1 / GPIO.HIGH / True. 
+
+## Output to several channels
+
+You can output to many channels in the same call (release 0.5.8 onwards).  For example:
+
+    :::python
+    chan_list = [11,12]                             # also works with tuples
+    GPIO.output(chan_list, GPIO.LOW)                # sets all to GPIO.LOW
+    GPIO.output(chan_list, (GPIO.HIGH, GPIO.LOW))   # sets first HIGH and second LOW

 ## Cleanup

BasicUsage modified by Ben Croston

Ben Croston — Sat, 25 Jan 2014 15:36:19 -0000

--- v3
+++ v4
@@ -82,7 +82,7 @@

 ## Cleanup

-At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used. 
+At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs with no pull up/down, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used. 

 To clean up at the end of your script:

BasicUsage modified by Ben Croston

Ben Croston — Sat, 04 Jan 2014 20:34:53 -0000

--- v2
+++ v3
@@ -89,6 +89,11 @@
     :::python
     GPIO.cleanup()

+It is possible that you only want to clean up one channel, leaving some set up when your program exits:
+
+    :::python
+    GPIO.cleanup(channel)
+
 ## RPi Board Revision and RPi.GPIO version

 To discover the Raspberry Pi board revision:

BasicUsage modified by Ben Croston

Ben Croston — Sat, 21 Dec 2013 22:48:37 -0000

--- v1
+++ v2
@@ -2,14 +2,16 @@

 ## Importing the module

-To import the RPi.GPIO module: 
-    
+To import the RPi.GPIO module:
+
+    :::python
     import RPi.GPIO as GPIO

 By doing it this way, you can refer to it as just GPIO through the rest of your script. 

-To import the module and check to see if it is successful: 
-    
+To import the module and check to see if it is successful:
+
+    :::python    
     try:
         import RPi.GPIO as GPIO
     except RuntimeError:
@@ -21,50 +23,57 @@

 The second numbering system is the BCM numbers. This is a lower level way of working - it refers to the channel numbers on the Broadcom SOC. You have to always work with a diagram of which channel number goes to which pin on the RPi board. Your script could break between revisions of Raspberry Pi boards. 

-To specify which you are using using (mandatory): 
-    
+To specify which you are using using (mandatory):
+
+    :::python
     GPIO.setmode(GPIO.BOARD)
-      or
+      # or
     GPIO.setmode(GPIO.BCM)

 ## Warnings

-It is possible that you have more than one script/circuit on the GPIO of your Raspberry Pi. As a result of this, if RPi.GPIO detects that a pin has been configured to something other than the default (input), you get a warning when you try to configure a script. To disable these warnings: 
-    
+It is possible that you have more than one script/circuit on the GPIO of your Raspberry Pi. As a result of this, if RPi.GPIO detects that a pin has been configured to something other than the default (input), you get a warning when you try to configure a script. To disable these warnings:
+
+    :::python
     GPIO.setwarnings(False)

 ## Setup up a channel

-You need to set up every channel you are using as an input or an output. To configure a channel as an input: 
-    
+You need to set up every channel you are using as an input or an output. To configure a channel as an input:
+
+    :::python
     GPIO.setup(channel, GPIO.IN)

 (where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). 

 More advanced information about setting up input channels can be found [here](Inputs). 

-To set up a channel as an output: 
-    
+To set up a channel as an output:
+
+    :::python
     GPIO.setup(channel, GPIO.OUT)

 (where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). 

-You can also specify an initial value for your output channel: 
-    
+You can also specify an initial value for your output channel:
+
+    :::python
     GPIO.setup(channel, GPIO.OUT, initial=GPIO.HIGH)

 ## Input

-To read the value of a GPIO pin: 
-    
+To read the value of a GPIO pin:
+
+    :::python
     GPIO.input(channel)

 (where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). This will return either 0 / GPIO.LOW / False or 1 / GPIO.HIGH / True. 

 ## Output

-To set the output state of a GPIO pin: 
-    
+To set the output state of a GPIO pin:
+
+    :::python
     GPIO.output(channel, state)

 (where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). 
@@ -75,8 +84,9 @@

 At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used. 

-To clean up at the end of your script: 
-    
+To clean up at the end of your script:
+
+    :::python
     GPIO.cleanup()

 ## RPi Board Revision and RPi.GPIO version

BasicUsage modified by Anonymous

Anonymous — Wed, 18 Dec 2013 16:59:33 -0000

RPi.GPIO module basics

Importing the module

To import the RPi.GPIO module:

import RPi.GPIO as GPIO

By doing it this way, you can refer to it as just GPIO through the rest of your script.

To import the module and check to see if it is successful:

try:
    import RPi.GPIO as GPIO
except RuntimeError:
    print("Error importing RPi.GPIO!  This is probably because you need superuser privileges.  You can achieve this by using 'sudo' to run your script")

Pin numbering

There are two ways of numbering the IO pins on a Raspberry Pi within RPi.GPIO. The first is using the BOARD numbering system. This refers to the pin numbers on the P1 header of the Raspberry Pi board. The advantage of using this numbering system is that your hardware will always work, regardless of the board revision of the RPi. You will not need to rewire your connector or change your code.

The second numbering system is the BCM numbers. This is a lower level way of working - it refers to the channel numbers on the Broadcom SOC. You have to always work with a diagram of which channel number goes to which pin on the RPi board. Your script could break between revisions of Raspberry Pi boards.

To specify which you are using using (mandatory):

GPIO.setmode(GPIO.BOARD)
  or
GPIO.setmode(GPIO.BCM)

Warnings

It is possible that you have more than one script/circuit on the GPIO of your Raspberry Pi. As a result of this, if RPi.GPIO detects that a pin has been configured to something other than the default (input), you get a warning when you try to configure a script. To disable these warnings:

GPIO.setwarnings(False)

Setup up a channel

You need to set up every channel you are using as an input or an output. To configure a channel as an input:

GPIO.setup(channel, GPIO.IN)

(where channel is the channel number based on the numbering system you have specified (BOARD or BCM)).

More advanced information about setting up input channels can be found here.

To set up a channel as an output:

GPIO.setup(channel, GPIO.OUT)

(where channel is the channel number based on the numbering system you have specified (BOARD or BCM)).

You can also specify an initial value for your output channel:

GPIO.setup(channel, GPIO.OUT, initial=GPIO.HIGH)

Input

To read the value of a GPIO pin:

GPIO.input(channel)

(where channel is the channel number based on the numbering system you have specified (BOARD or BCM)). This will return either 0 / GPIO.LOW / False or 1 / GPIO.HIGH / True.

Output

To set the output state of a GPIO pin:

GPIO.output(channel, state)

(where channel is the channel number based on the numbering system you have specified (BOARD or BCM)).

State can be 0 / GPIO.LOW / False or 1 / GPIO.HIGH / True.

Cleanup

At the end any program, it is good practice to clean up any resources you might have used. This is no different with RPi.GPIO. By returning all channels you have used back to inputs, you can avoid accidental damage to your RPi by shorting out the pins. Note that this will only clean up GPIO channels that your script has used.

To clean up at the end of your script:

GPIO.cleanup()

RPi Board Revision and RPi.GPIO version

To discover the Raspberry Pi board revision:

GPIO.RPI_REVISION

To discover the version of RPi.GPIO:

GPIO.VERSION