A CHIP GPIO library
Manual Installation:
For Python2.7:
sudo apt-get update sudo apt-get install git build-essential python-dev python-pip flex bison chip-dt-overlays -y git clone git://github.com/xtacocorex/CHIP_IO.git cd CHIP_IO sudo python setup.py install cd ..
For Python3:
sudo apt-get update sudo apt-get install git build-essential python3-dev python3-pip flex bison chip-dt-overlays -y git clone git://github.com/xtacocorex/CHIP_IO.git cd CHIP_IO sudo python3 setup.py install cd ..
PyPi Installation:
For Python2.7:
sudo apt-get update sudo apt-get install git build-essential python-dev python-pip flex bison chip-dt-overlays -y sudo pip install CHIP-IO
For Python3:
sudo apt-get update sudo apt-get install git build-essential python3-dev python3-pip flex bison chip-dt-overlays -y sudo pip3 install CHIP-IO
Usage
Using the library is very similar to the excellent RPi.GPIO library used on the Raspberry Pi. Below are some examples.
All scripts that require GPIO, PWM (HW and/or SW), and Overlay Manager need to be run with super user permissions!
Allowable Pin Names for the Library
The following "table" is the allowable pin names that are able to be used by the library. The Name column is the normal name used on the CHIP Headers, the Alt Name column is the value used by the PocketCHIP header (if it's broken out), and the Key is the Header and Pin Number the the Pin is physically located. Either of these 3 means is able to specify a pin in CHIP_IO.
CHIP (Name) PocketCHIP/CHIP Pro Name CHIP Key HW Support TWI1-SDA KPD-I2C-SDA U13_9 CHIP/CHIP PRO TWI1-SCK KPD-I2C-SCL U13_11 CHIP/CHIP PRO LCD-D2 UART2-TX U13_17 CHIP/CHIP PRO PWM0 PWM0 U13_18 CHIP/CHIP PRO PWM1 PWM1 EINT13 CHIP PRO LCD-D4 UART2-CTS U13_19 CHIP/CHIP PRO LCD-D3 UART2-RX U13_20 CHIP/CHIP PRO LCD-D6 LCD-D6 U13_21 CHIP LCD-D5 UART2-RTS U13_22 CHIP/CHIP PRO LCD-D10 LCD-D10 U13_23 CHIP LCD-D7 LCD-D7 U13_24 CHIP LCD-D12 LCD-D12 U13_25 CHIP LCD-D11 LCD-D11 U13_26 CHIP LCD-D14 LCD-D14 U13_27 CHIP LCD-D13 LCD-D13 U13_28 CHIP LCD-D18 LCD-D18 U13_29 CHIP LCD-D15 LCD-D15 U13_30 CHIP LCD-D20 LCD-D20 U13_31 CHIP LCD-D19 LCD-D19 U13_32 CHIP LCD-D22 LCD-D22 U13_33 CHIP LCD-D21 LCD-D21 U13_34 CHIP LCD-CLK LCD-CLK U13_35 CHIP LCD-D23 LCD-D23 U13_36 CHIP LCD-VSYNC LCD-VSYNC U13_37 CHIP LCD-HSYNC LCD-HSYNC U13_38 CHIP LCD-DE LCD-DE U13_40 CHIP UART1-TX UART-TX U14_3 CHIP/CHIP PRO UART1-RX UART-RX U14_5 CHIP/CHIP PRO LRADC ADC U14_11 CHIP/CHIP PRO XIO-P0 XIO-P0 U14_13 CHIP XIO-P1 XIO-P1 U14_14 CHIP XIO-P2 GPIO1 U14_15 CHIP XIO-P3 GPIO2 U14_16 CHIP XIO-P4 GPIO3 U14_17 CHIP XIO-P5 GPIO4 U14_18 CHIP XIO-P6 GPIO5 U14_19 CHIP XIO-P7 GPIO6 U14_20 CHIP AP-EINT1 KPD-INT U14_23 CHIP/CHIP PRO AP-EINT3 AP-INT3 U14_24 CHIP/CHIP PRO TWI2-SDA I2C-SDA U14_25 CHIP/CHIP PRO TWI2-SCK I2C-SCL U14_26 CHIP/CHIP PRO CSIPCK SPI-SEL U14_27 CHIP/CHIP PRO CSICK SPI-CLK U14_28 CHIP/CHIP PRO CSIHSYNC SPI-MOSI U14_29 CHIP/CHIP PRO CSIVSYNC SPI-MISO U14_30 CHIP/CHIP PRO CSID0 D0 U14_31 CHIP/CHIP PRO CSID1 D1 U14_32 CHIP/CHIP PRO CSID2 D2 U14_33 CHIP/CHIP PRO CSID3 D3 U14_34 CHIP/CHIP PRO CSID4 D4 U14_35 CHIP/CHIP PRO CSID5 D5 U14_36 CHIP/CHIP PRO CSID6 D6 U14_37 CHIP/CHIP PRO CSID7 D7 U14_38 CHIP/CHIP PRO
GPIO Setup
Import the library, and setup as GPIO.OUT or GPIO.IN:
import CHIP_IO.GPIO as GPIO
GPIO.setup("CSID0", GPIO.OUT)
You can also refer to the pin number:
GPIO.setup("U14_31", GPIO.OUT)
You can also refer to the bin based upon its alternate name:
GPIO.setup("GPIO1", GPIO.IN)
GPIO Miscellaneous
Debug can be enabled/disabled by the following command:
# Enable Debug GPIO.toggle_debug()
You can determine if the hardware is a CHIP/CHIP Pro using the following:
# Determine hardware # 0 For CHIP # 1 For CHIP Pro GPIO.is_chip_pro()
GPIO Output
Setup the pin for output, and write GPIO.HIGH or GPIO.LOW. Or you can use 1 or 0.:
import CHIP_IO.GPIO as GPIO
GPIO.setup("CSID0", GPIO.OUT)
GPIO.output("CSID0", GPIO.HIGH)
GPIO Input
Inputs work similarly to outputs.:
import CHIP_IO.GPIO as GPIO
GPIO.setup("CSID0", GPIO.IN)
Other options when setting up pins:
# Specify pull up/pull down settings on a pin
GPIO.setup("CSID0", GPIO.IN, pull_up_down=GPIO.PUD_UP)
# Specify initial value for an output
GPIO.setup("CSID0", GPIO.OUT, initial=1)
Pull Up/Down values are only for pins that are provided by the R8, the XIO are not capable of this. The allowable values are: PUD_OFF, PUD_UP, and PUD_DOWN.
Polling inputs:
if GPIO.input("CSID0"):
print("HIGH")
else:
print("LOW")
Read lots of data:
# Get 8 bits of data in one shot
mybyte = GPIO.read_byte("LCD-D3")
# Get 16 bits of data in one shot
myword = GPIO.read_word("XIO-P4")
This code was initially added by brettcvz and I cleaned it up and expanded it.
You can quickly change a pins direction:
GPIO.direction("XIO-P3", GPIO.OUT)
GPIO.direction("XIO-P3", GPIO.IN)
You can also re-setup a pin in order to change direction, not that this is a slower operation:
GPIO.setup("XIO-P3", GPIO.OUT)
GPIO.setup("XIO-P3", GPIO.IN)
The edge detection code below only works for the AP-EINT1, AP-EINT3, and XPO Pins on the CHIP.
Waiting for an edge (GPIO.RISING, GPIO.FALLING, or GPIO.BOTH:
GPIO.wait_for_edge(channel, GPIO.RISING)
Detecting events:
GPIO.setup("XIO-P0", GPIO.IN)
GPIO.add_event_detect("XIO-P0", GPIO.FALLING)
#your amazing code here
#detect wherever:
if GPIO.event_detected("XIO-P0"):
print "event detected!"
CHIP_IO can also handle adding callback functions on any pin that supports edge detection. Note that only one callback function can be specified per Pin, if you try to set more, an exception will be thrown.:
def mycallback(channel):
print("we hit the edge we want")
GPIO.setup("GPIO3", GPIO.IN)
# Add Event Detect and Callback Separately for Falling Edge
GPIO.add_event_detect("GPIO3", GPIO.FALLING)
GPIO.add_event_callback("GPIO3", mycallback)
# Add Event Detect and Callback Separately for Rising Edge
GPIO.add_event_detect("GPIO3", GPIO.RISING)
GPIO.add_event_callback("GPIO3", mycallback)
# Add Callback for Both Edges using the add_event_detect() method
GPIO.add_event_detect("GPIO3", GPIO.BOTH, mycallback)
# Remove callback with the following
GPIO.remove_event_detect("GPIO3")
GPIO Cleanup
To clean up the GPIO when done, do the following:
# Clean up every exported GPIO Pin
GPIO.cleanup()
# Clean up a single pin (keeping everything else intact)
GPIO.cleanup("XIO-P0")
PWM:
Hardware PWM requires a DTB Overlay loaded on the CHIP to allow the kernel to know there is a PWM device available to use.
import CHIP_IO.PWM as PWM
# Determine hardware
# 0 For CHIP
# 1 For CHIP Pro
PWM.is_chip_pro()
# Enable/Disable Debug
PWM.toggle_debug()
#PWM.start(channel, duty, freq=2000, polarity=0)
#duty values are valid 0 (off) to 100 (on)
PWM.start("PWM0", 50)
PWM.set_duty_cycle("PWM0", 25.5)
PWM.set_frequency("PWM0", 10)
# To stop PWM
PWM.stop("PWM0")
PWM.cleanup()
#For specific polarity: this example sets polarity to 1 on start:
PWM.start("PWM0", 50, 2000, 1)
SOFTPWM:
import CHIP_IO.SOFTPWM as SPWM
# Determine hardware
# 0 For CHIP
# 1 For CHIP Pro
SPWM.is_chip_pro()
# Enable/Disable Debug
SPWM.toggle_debug()
#SPWM.start(channel, duty, freq=2000, polarity=0)
#duty values are valid 0 (off) to 100 (on)
#you can choose any pin
SPWM.start("XIO-P7", 50)
SPWM.set_duty_cycle("XIO-P7", 25.5)
SPWM.set_frequency("XIO-P7", 10)
# To Stop SPWM
SPWM.stop("XIO-P7")
# Cleanup
SPWM.cleanup()
#For specific polarity: this example sets polarity to 1 on start:
SPWM.start("XIO-P7", 50, 2000, 1)
Use SOFTPWM at low speeds (hundreds of Hz) for the best results. Do not use for anything that needs high precision or reliability.
If using SOFTPWM and PWM at the same time, import CHIP_IO.SOFTPWM as SPWM or something different than PWM as to not confuse the library.
SERVO:
import CHIP_IO.SERVO as SERVO
# Determine hardware
# 0 For CHIP
# 1 For CHIP Pro
SERVO.is_chip_pro()
# Enable/Disable Debug
SERVO.toggle_debug()
#SPWM.start(channel, angle=0, range=180)
#angle values are between +/- range/2)
#you can choose any pin except the XIO's
SERVO.start("CSID4", 50)
SERVO.set_angle("CSID4", 25.5)
SERVO.set_range("CSID4", 90)
# To Stop Servo
SERVO.stop("CSID4")
# Cleanup
SERVO.cleanup()
The Software Servo control only works on the LCD and CSI pins. The XIO is too slow to control.
LRADC:
The LRADC was enabled in the 4.4.13-ntc-mlc. This is a 6 bit ADC that is 2 Volt tolerant. Sample code below details how to talk to the LRADC.:
import CHIP_IO.LRADC as ADC # Enable/Disable Debug ADC.toggle_debug() # Check to see if the LRADC Device exists # Returns True/False ADC.get_device_exists() # Setup the LRADC # Specify a sampling rate if needed ADC.setup(rate) # Get the Scale Factor factor = ADC.get_scale_factor() # Get the allowable Sampling Rates sampleratestuple = ADC.get_allowable_sample_rates() # Set the sampling rate ADC.set_sample_rate(rate) # Get the current sampling rate currentrate = ADC.get_sample_rate() # Get the Raw Channel 0 or 1 data raw = ADC.get_chan0_raw() raw = ADC.get_chan1_raw() # Get the factored ADC Channel data fulldata = ADC.get_chan0() fulldata = ADC.get_chan1()
SPI:
SPI requires a DTB Overlay to access. CHIP_IO does not contain any SPI specific code as the Python spidev module works when it can see the SPI bus.
Overlay Manager:
The Overlay Manager enables you to quickly load simple Device Tree Overlays. The options for loading are: PWM0, SPI2, CUST. The Overlay Manager is smart enough to determine if you are trying to load PWM on a CHIP Pro and will fail due to the base DTB for the CHIP Pro supporting PWM0/1 out of the box.
Only one of each type of overlay can be loaded at a time, but all three options can be loaded simultaneously. So you can have SPI2 without PWM0, but you cannot have SPI2 loaded twice.
import CHIP_IO.OverlayManager as OM
# The toggle_debug() function turns on/off debug printing
#OM.toggle_debug()
# To load an overlay, feed in the name to load()
OM.load("PWM0")
# To verify the overlay was properly loaded, the get_ functions return booleans
OM.get_pwm_loaded()
OM.get_spi_loaded()
# To unload an overlay, feed in the name to unload()
OM.unload("PWM0")
To use a custom overlay, you must build and compile it properly per the DIP Docs: http://docs.getchip.com/dip.html#development-by-example There is no verification that the Custom Overlay is setup properly, it's fire and forget
import CHIP_IO.OverlayManager as OM
# The full path to the dtbo file needs to be specified
OM.load("CUST","/home/chip/projects/myfunproject/overlays/mycustomoverlay.dtbo")
# You can check for loading like above, but it's really just there for sameness
OM.get_custom_loaded()
# To unload, just call unload()
OM.unload("CUST")
OverlayManager requires a 4.4 kernel with the CONFIG_OF_CONFIGFS option enabled in the kernel config.
Utilties:
CHIP_IO now supports the ability to enable and disable the 1.8V port on U13. This voltage rail isn't enabled during boot.
To use the utilities, here is sample code:
import CHIP_IO.Utilities as UT # Enable/Disable Debug UT.toggle_debug() # Enable 1.8V Output UT.enable_1v8_pin() # Set 2.0V Output UT.set_1v8_pin_voltage(2.0) # Set 2.6V Output UT.set_1v8_pin_voltage(2.6) # Set 3.3V Output UT.set_1v8_pin_voltage(3.3) # Disable 1.8V Output UT.disable_1v8_pin() # Get currently-configured voltage (returns False if the pin is not enabled as output) UT.get_1v8_pin_voltage() # Unexport Everything UT.unexport_all() # Determine if you are running a CHIP/CHIP Pro # This returns True if the computer is a CHIP Pro and False if it is a CHIP UT.is_chip_pro()
Running tests
Install py.test to run the tests. You'll also need the python compiler package for py.test.:
# Python 2.7 sudo apt-get install python-pytest # Python 3 sudo apt-get install python3-pytest
To run the tests, do the following.:
# If only one version of Python is installed # Python 2 sudo make pytest2 # Python 3 sudo make pytest3 # If more than one version of Python, run through both sudo make test
Credits
The CHIP IO Python library was originally forked from the Adafruit Beaglebone IO Python Library. The BeagleBone IO Python library was originally forked from the excellent MIT Licensed [RPi.GPIO](https://code.google.com/p/raspberry-gpio-python) library written by Ben Croston.
License
CHIP IO port by Robert Wolterman, released under the MIT License. Beaglebone IO Library Written by Justin Cooper, Adafruit Industries. BeagleBone IO Python library is released under the MIT License.