This example shows how to use the Grove Light Sensor v1.1. You will also see how to plot a graph using matplotlib.
The Grove Light Sensor produces an analog signal which requires an ADC.
The Grove Light Sensor, PYNQ Grove Adapter, and Grove I2C ADC are used for this example.
When the ambient light intensity increases, the resistance of the LDR or Photoresistor will decrease. This means that the output signal from this module will be HIGH in bright light, and LOW in the dark. Values for the sensor ranges from ~5.0 (bright) to >35.0 (dark).
In :from pynq import Overlay Overlay("base.bit").download()
In :from pynq.iop import Grove_Light from pynq.iop import PMODA from pynq.iop import PMOD_GROVE_G4 lgt = Grove_Light(PMODA, PMOD_GROVE_G4) sensor_val = lgt.read() print(sensor_val)
This Python code will do multiple light measurements over a 10 second period.
To change the light intensity, cover and uncover the light sensor. In typical ambient light, there is no need to provide an external light source, as the sensor is already reading at full scale.
In :import time %matplotlib inline import matplotlib.pyplot as plt lgt.set_log_interval_ms(100) lgt.start_log() # Change input during this time time.sleep(10) r_log = lgt.get_log() plt.plot(range(len(r_log)), r_log, 'ro') plt.title('Grove Light Plot') min_r_log = min(r_log) max_r_log = max(r_log) plt.axis([0, len(r_log), min_r_log, max_r_log]) plt.show()