A CHIP IO library for Python: IO+PWM+SPWM+ADC+Utilities
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README.rst

CHIP_IO

A CHIP GPIO library

Debian File Installation:

There are now pre-compiled binary deb files for the CHIP that do not require any build tools on a CHIP/CHIP Pro.

Go to this page: https://github.com/xtacocorex/CHIP_IO/releases/latest Or Go to this page: https://xtacocorex.github.io/chip_io_releases/index.html

Download the .deb file for the version of Python you are running. Then install with dpkg, like the following example:

sudo dpkg -i python-chip-io_0.5.9-1_armhf.deb

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 (Main Name) PocketCHIP/CHIP Pro Name Key (Alt Name) HW Support Edge Detect
TWI1-SDA KPD-I2C-SDA U13_9 CHIP/CHIP PRO NO
TWI1-SCK KPD-I2C-SCL U13_11 CHIP/CHIP PRO NO
LCD-D2 UART2-TX U13_17 CHIP/CHIP PRO NO
PWM0 PWM0 U13_18 CHIP/CHIP PRO NO
PWM1 PWM1 EINT13 CHIP PRO YES
LCD-D4 UART2-CTS U13_19 CHIP/CHIP PRO NO
LCD-D3 UART2-RX U13_20 CHIP/CHIP PRO NO
LCD-D6 LCD-D6 U13_21 CHIP NO
LCD-D5 UART2-RTS U13_22 CHIP/CHIP PRO NO
LCD-D10 LCD-D10 U13_23 CHIP NO
LCD-D7 LCD-D7 U13_24 CHIP NO
LCD-D12 LCD-D12 U13_25 CHIP NO
LCD-D11 LCD-D11 U13_26 CHIP NO
LCD-D14 LCD-D14 U13_27 CHIP NO
LCD-D13 LCD-D13 U13_28 CHIP NO
LCD-D18 LCD-D18 U13_29 CHIP NO
LCD-D15 LCD-D15 U13_30 CHIP NO
LCD-D20 LCD-D20 U13_31 CHIP NO
LCD-D19 LCD-D19 U13_32 CHIP NO
LCD-D22 LCD-D22 U13_33 CHIP NO
LCD-D21 LCD-D21 U13_34 CHIP NO
LCD-CLK LCD-CLK U13_35 CHIP NO
LCD-D23 LCD-D23 U13_36 CHIP NO
LCD-VSYNC LCD-VSYNC U13_37 CHIP NO
LCD-HSYNC LCD-HSYNC U13_38 CHIP NO
LCD-DE LCD-DE U13_40 CHIP NO
UART1-TX UART-TX U14_3 CHIP/CHIP PRO NO
UART1-RX UART-RX U14_5 CHIP/CHIP PRO NO
LRADC ADC U14_11 CHIP/CHIP PRO NO
XIO-P0 XIO-P0 U14_13 CHIP YES
XIO-P1 XIO-P1 U14_14 CHIP YES
XIO-P2 GPIO1 U14_15 CHIP YES
XIO-P3 GPIO2 U14_16 CHIP YES
XIO-P4 GPIO3 U14_17 CHIP YES
XIO-P5 GPIO4 U14_18 CHIP YES
XIO-P6 GPIO5 U14_19 CHIP YES
XIO-P7 GPIO6 U14_20 CHIP YES
AP-EINT1 KPD-INT U14_23 CHIP/CHIP PRO YES
AP-EINT3 AP-INT3 U14_24 CHIP/CHIP PRO YES
TWI2-SDA I2C-SDA U14_25 CHIP/CHIP PRO NO
TWI2-SCK I2C-SCL U14_26 CHIP/CHIP PRO NO
CSIPCK SPI-SEL U14_27 CHIP/CHIP PRO NO
CSICK SPI-CLK U14_28 CHIP/CHIP PRO NO
CSIHSYNC SPI-MOSI U14_29 CHIP/CHIP PRO NO
CSIVSYNC SPI-MISO U14_30 CHIP/CHIP PRO NO
CSID0 D0 U14_31 CHIP/CHIP PRO NO
CSID1 D1 U14_32 CHIP/CHIP PRO NO
CSID2 D2 U14_33 CHIP/CHIP PRO NO
CSID3 D3 U14_34 CHIP/CHIP PRO NO
CSID4 D4 U14_35 CHIP/CHIP PRO NO
CSID5 D5 U14_36 CHIP/CHIP PRO NO
CSID6 D6 U14_37 CHIP/CHIP PRO NO
CSID7 D7 U14_38 CHIP/CHIP PRO NO
I2S-MCLK EINT19 21 CHIP PRO YES
I2S-BCLK I2S-BCLK 22 CHIP PRO NO
I2S-LCLK I2S-LCLK 23 CHIP PRO NO
I2S-DO EINT19 24 CHIP PRO NO
I2S-DI EINT24 25 CHIP PRO YES

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, note 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")

# bouncetime is also able to be set for both GPIO.add_event_detect() and GPIO.add_event_callback()
GPIO.add_event_detect("GPIO3", GPIO.FALLING, bouncetime=300)
GPIO.add_event_callback("GPIO3", GPIO.RISING, mycallback, bouncetime=300)

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.