aagpio.py

Aardvark Example Source Code Version: 4.00 Date: 2007-04-20 Source code which shows how to use the

#!/bin/env python
#==========================================================================
# (c) 2004-2006  Total Phase, Inc.
#--------------------------------------------------------------------------
# Project : Aardvark Sample Code
# File    : aagpio.py
#--------------------------------------------------------------------------
# Perform some simple GPIO operations with a single Aardvark adapter.
#--------------------------------------------------------------------------
# Redistribution and use of this file in source and binary forms, with
# or without modification, are permitted.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#==========================================================================

#==========================================================================
# IMPORTS
#==========================================================================
import sys

from aardvark_py import *


#==========================================================================
# MAIN PROGRAM
#==========================================================================
if (len(sys.argv) < 2):
    print "usage: aagpio PORT"
    sys.exit()

port = int(sys.argv[1])

# Open the device
(handle, aaext) = aa_open_ext(port)
if (handle <= 0):
    print "Unable to open Aardvark device on port %d" % port
    print "Error code = %d" % handle
    sys.exit()
    
print "Opened Aardvark adapter; features = 0x%02x" % aaext.features

# Configure the Aardvark adapter so all pins
# are now controlled by the GPIO subsystem
aa_configure(handle,  AA_CONFIG_GPIO_ONLY)
    
# Configure the Aardvark adapter so all pins
# are now controlled by the GPIO subsystem
aa_configure(handle, AA_CONFIG_GPIO_ONLY)

# Turn off the external I2C line pullups
aa_i2c_pullup(handle, AA_I2C_PULLUP_NONE)

# Make sure the charge has dissipated on those lines
aa_gpio_set(handle, 0x00)
aa_gpio_direction(handle, 0xff)

# By default all GPIO pins are inputs.  Writing 1 to the
# bit position corresponding to the appropriate line will
# configure that line as an output
aa_gpio_direction(handle, AA_GPIO_SS | AA_GPIO_SCL)

# By default all GPIO outputs are logic low.  Writing a 1
# to the appropriate bit position will force that line
# high provided it is configured as an output.  If it is
# not configured as an output the line state will be
# cached such that if the direction later changed, the
# latest output value for the line will be enforced.
aa_gpio_set(handle, AA_GPIO_SCL)
print "Setting SCL to logic low"

# The get method will return the line states of all inputs.
# If a line is not configured as an input the value of
# that particular bit position in the mask will be 0.
val = aa_gpio_get(handle)

# Check the state of SCK
if (val & AA_GPIO_SCK):
    print "Read the SCK line as logic high"
else:
    print "Read the SCK line as logic low"
    
# Optionally we can set passive pullups on certain lines.
# This can prevent input lines from floating.  The pullup
# configuration is only valid for lines configured as inputs.
# If the line is not currently input the requested pullup
# state will take effect only if the line is later changed
# to be an input line.
aa_gpio_pullup(handle, AA_GPIO_MISO | AA_GPIO_MOSI)

# Now reading the MISO line should give a logic high,
# provided there is nothing attached to the Aardvark
# adapter that is driving the pin low.
val = aa_gpio_get(handle)
if (val & AA_GPIO_MISO):
    print "Read the MISO line as logic high (passive pullup)"
else:
    print "Read the MISO line as logic low (is pin driven low?)"

# Now do a 1000 gets from the GPIO to test performance
for i in range(1000):
    aa_gpio_get(handle)
    
# Demonstrate use of aa_gpio_change
aa_gpio_direction(handle, 0x00)
oldval = aa_gpio_get(handle)
print "Calling aa_gpio_change for 2 seconds..."
newval = aa_gpio_change(handle, 2000)
if (newval != oldval):
    print "  GPIO inputs changed."
else:
    print "  GPIO inputs did not change."

# Turn on the I2C line pullups since we are done
aa_i2c_pullup(handle, AA_I2C_PULLUP_BOTH)

# Configure the Aardvark adapter back to SPI/I2C mode.
aa_configure(handle, AA_CONFIG_SPI_I2C)
    
# Close the device
aa_close(handle)