Simple test¶
Ensure your device works with this simple test.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | # SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
# This simple test outputs a 50% duty cycle PWM single on the 0th channel. Connect an LED and
# resistor in series to the pin to visualize duty cycle changes and its impact on brightness.
from board import SCL, SDA
import busio
# Import the PCA9685 module.
from adafruit_pca9685 import PCA9685
# Create the I2C bus interface.
i2c_bus = busio.I2C(SCL, SDA)
# Create a simple PCA9685 class instance.
pca = PCA9685(i2c_bus)
# Set the PWM frequency to 60hz.
pca.frequency = 60
# Set the PWM duty cycle for channel zero to 50%. duty_cycle is 16 bits to match other PWM objects
# but the PCA9685 will only actually give 12 bits of resolution.
pca.channels[0].duty_cycle = 0x7FFF
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | # SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
# This advanced example can be used to compute a more precise reference_clock_speed. Use an
# oscilloscope or logic analyzer to measure the signal frequency and type the results into the
# prompts. At the end it'll give you a more precise value around 25 mhz for your reference clock
# speed.
import time
from board import SCL, SDA
import busio
# Import the PCA9685 module.
from adafruit_pca9685 import PCA9685
# Create the I2C bus interface.
i2c_bus = busio.I2C(SCL, SDA)
# Create a simple PCA9685 class instance.
pca = PCA9685(i2c_bus)
# Set the PWM frequency to 100hz.
pca.frequency = 100
input("Press enter when ready to measure default frequency.")
# Set the PWM duty cycle for channel zero to 50%. duty_cycle is 16 bits to match other PWM objects
# but the PCA9685 will only actually give 12 bits of resolution.
print("Running with default calibration")
pca.channels[0].duty_cycle = 0x7FFF
time.sleep(1)
pca.channels[0].duty_cycle = 0
measured_frequency = float(input("Frequency measured: "))
print()
pca.reference_clock_speed = pca.reference_clock_speed * (
measured_frequency / pca.frequency
)
# Set frequency again so we can get closer. Reading it back will produce the real value.
pca.frequency = 100
input("Press enter when ready to measure coarse calibration frequency.")
pca.channels[0].duty_cycle = 0x7FFF
time.sleep(1)
pca.channels[0].duty_cycle = 0
measured_after_calibration = float(input("Frequency measured: "))
print()
reference_clock_speed = measured_after_calibration * 4096 * pca.prescale_reg
print("Real reference clock speed: {0:.0f}".format(reference_clock_speed))
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | # SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
# This example moves a servo its full range (180 degrees by default) and then back.
from board import SCL, SDA
import busio
# This example also relies on the Adafruit motor library available here:
# https://github.com/adafruit/Adafruit_CircuitPython_Motor
from adafruit_motor import servo
# Import the PCA9685 module.
from adafruit_pca9685 import PCA9685
i2c = busio.I2C(SCL, SDA)
# Create a simple PCA9685 class instance.
pca = PCA9685(i2c)
pca.frequency = 50
# To get the full range of the servo you will likely need to adjust the min_pulse and max_pulse to
# match the stall points of the servo.
# This is an example for the Sub-micro servo: https://www.adafruit.com/product/2201
# servo7 = servo.Servo(pca.channels[7], min_pulse=580, max_pulse=2480)
# This is an example for the Micro Servo - High Powered, High Torque Metal Gear:
# https://www.adafruit.com/product/2307
# servo7 = servo.Servo(pca.channels[7], min_pulse=600, max_pulse=2400)
# This is an example for the Standard servo - TowerPro SG-5010 - 5010:
# https://www.adafruit.com/product/155
# servo7 = servo.Servo(pca.channels[7], min_pulse=600, max_pulse=2500)
# This is an example for the Analog Feedback Servo: https://www.adafruit.com/product/1404
# servo7 = servo.Servo(pca.channels[7], min_pulse=600, max_pulse=2600)
# The pulse range is 1000 - 2000 by default.
servo7 = servo.Servo(pca.channels[7])
for i in range(180):
servo7.angle = i
for i in range(180):
servo7.angle = 180 - i
pca.deinit()
|