General Information
I installed the RPi SenseHAT on a RPi Zero W running DietPi. I created a Python Script to control the Joystick and the LED Matrix Output (code and screenshot below). I added a Service file to have the script start at boot, however the Service is causing the CPU to run at 100% all the time - unless an event is triggered by the Joystick, which brings the CPU usage down. When the event has finished, the CPU usage returns to 100%.
Is this normal? Did I set up the Python Script incorrectly? Did I set up the Service file incorrectly? Is there a better way to have this script run at boot?
Required Information
-
DietPi Version:
- G_DIETPI_VERSION_CORE=8
- G_DIETPI_VERSION_SUB=6
- G_DIETPI_VERSION_RC=1
- G_GITBRANCH=‘master’
- G_GITOWNER=‘MichaIng’
- G_LIVE_PATCH_STATUS[0]=‘applied’
- G_LIVE_PATCH_STATUS[1]=‘applied’
- Distro Version | bullseye 1
- Kernel Version | Linux SensePi 5.15.32+ #1538 Thu Mar 31 19:37:58 BST 2022 armv6l GNU/Linux
- SBC Model | RPi Zero W (armv6l)
- Power Supply Used | 5V 2.1A Anker Power Block
- SD Card Used | MicroCenter 16GB SD Card
Steps to Reproduce
- Add Python Script to ‘systemd’ folder (/lib/systemd/system).
- Use DietPi-Services to add missing Service (Controlled by DietPi) to run Service at Boot.
- Reboot.
- Review htop Stats.
Expected Behaviour
The Pi should NOT be running at 100% CPU Usage while Idle
Actual Behaviour
The Pi is running at 100% CPU Usage while Idle, and drops to 5%-20% when SenseHAT Joystick is used.
Extra Details
systemd Service File - sensehat.service
[Unit]
Description=SenseHAT Temp Display
After=multi-user.target
[Service]
Type=idle
ExecStart=/usr/bin/python3 /root/tempctrl.py
User=root
[Install]
WantedBy=multi-user.target
Python Script File
#!/usr/bin/python
from sense_hat import SenseHat
import time
from time import sleep
sense = SenseHat()
sense.set_rotation(180)
sense.clear()
red = (255,0,0)
green = (0,255,0)
blue = (0,0,255)
def tempcolor():
temp = round(sense.get_temperature()*1.8 +32)
sense.low_light = True
if temp > 78:
sense.clear(red)
elif temp < 78 and temp > 65:
sense.clear(green)
elif temp < 65 and temp > 0:
sense.clear(blue)
sleep(5)
sense.clear()
sense.low_light = False
def temperaturecolor():
temp = round(sense.get_temperature()*1.8 +32)
sense.low_light = True
if temp > 78:
sense.clear(red)
elif temp < 78 and temp > 65:
sense.clear(green)
elif temp < 65 and temp > 0:
sense.clear(blue)
sleep(5)
sense.show_message((str(temp) + "F "), scroll_speed=(0.15), back_colour= [0,0,0])
sense.clear()
sense.low_light = False
def humiditycolor():
humidity = round(sense.get_humidity())
sense.low_light = True
if humidity > 55:
sense.clear(red)
elif humidity < 55 and humidity > 30:
sense.clear(green)
elif humidity < 30 and humidity > 0:
sense.clear(blue)
sleep(5)
sense.show_message((str(humidity) + "%"), scroll_speed=(0.15), back_colour= [0,0,0])
sense.clear()
sense.low_light = False
def temperature():
temp = round(sense.get_temperature()*1.8 +32)
sense.show_message((str(temp) + "F "), scroll_speed=(0.15), back_colour= [0,0,0])
def humidity():
humidity = round(sense.get_humidity())
sense.show_message((str(humidity) + "%"), scroll_speed=(0.15), back_colour= [0,0,0])
while True:
for event in sense.stick.get_events():
if event.action == "pressed":
if event.direction == "down":
temperaturecolor()
elif event.direction == "up":
humiditycolor()
elif event.direction == "left":
temperature()
elif event.direction == "right":
humidity()
elif event.direction == "middle":
tempcolor()
sleep(0.5)
Screenshots
The Script is running via a .service File added to Diet Pi Services. At idle, the CPU stays at 100%.
Using the SenseHAT Joystick to trigger an event…
When pressing the SenseHAT Joystick to trigger an event on the Sense HAT LED Matrix, CPU Usage drops to around 15% while the script is running an event.
Screenshot of the .service file.
Screenshot of the added Service on the DietPi-Services screen.
