From the course: Raspberry Pi Weekly
From the course: Raspberry Pi Weekly
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Dealing with undervoltage
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- There, do you see that lightning bolt? That says your Raspberry Pi is under voltage. Your power supply isn't keeping up with your Raspberry Pi. You might want to know how to detect this, how to test it, and how to fix it. Hi, I'm Mark Niemann-Ross, and welcome to this week's edition of "Raspberry Pi Weekly." Every week, we explore the Raspberry Pi and share useful tips. The Raspberry Pi needs five volts. At 4.63 volts, it's going to complain about low voltage. The Raspberry Pi will slow down the processor to match the drop in voltage. Much lower than 4.63 volts and your Raspberry Pi will stop working. Possibly worse than this, lower voltages will cause corruption on your SD card. To detect a low voltage, you can watch for the lightning bolt. But you can also the vcgencmd operation. To use vcgencmd, open a terminal and type in vcgencmd, followed by a space and then get_throttled, T-H-R-O-T-T-L-E-D. You'll get back the string throttled= followed by a number that starts with 0x. In this case, we're looking at throttled=0x50000. This is a hex number. It's actually a hex representation of a collection of one-bit flags. If only the first flag is on, the hex number would be 0x1. That would indicate an undervoltage is detected. Now, here's a table of all the flags. Notice that in the table, the first bit of vcgencmd get_throttled is referred to as bit zero. If an error occurs, that flag is turned on, and the binary value of that bit is added to vcgencmd get_throttled. In this case, bit one has a binary value of two, which is added to vcgencmd get_throttled and returns a result of two. So if an undervoltage is detected and the Raspberry Pi is currently throttled because of it, vcgencmd get_throttled will return throttled=0x5 followed by zeroes, which is the first bit plus the value of the third bit. And the Raspberry Pi is currently throttled because of it. Vcgencmd get_throttled will return throttled=0x5 which is the value of the first bit plus the value of the third bit. This is totally confusing, so I wrote a Python program that will read the value from vcgencmd get_throttled, then decipher the warning messages. Look in the Exercise Files for vcgencmd.pi, run it, and then compare your results to the suggestions on the table. In this case, you can see that vcgencmd has returned 0x5. The warning is undervoltage has occurred and throttling has occurred. Fixing undervoltage is easy. Get a better power supply. You may not be getting enough power from your old phone charger. Look for a higher quality unit, and test it with a voltmeter to make sure it's providing the power it's supposed to. Thanks for joining me for this episode of "Raspberry Pi Weekly." Be sure to join the LinkedIn group and check out previous episodes on LinkedIn Learning. I'll see you next week with more Raspberry Pi adventures.
Contents
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- Raspberry Pi Weekly 44s
- Why Raspberry Pi? 3m 45s
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- The Raspberry Pi family 3m 53s
- GPIO male to female jumpers 3m 30s
- Weatherproofing Pi 4m 19s
- Power and batteries 3m 57s
- IR rangefinder project 2m 26s
- Clock project 6m 20s
- Wire a stepper motor 3m 38s
- Code a stepper motor 3m 37s
- gpiozero library 4m 50s
- Take a screenshot 4m 26s
- Analog to digital 2m 38s
- Autostart file setup 4m 24s
- Simple connection to a speaker 2m 43s
- Red LED, RGB LED, blink, and glow 3m 23s
- Connect input to output: Range finder to LED 2m 4s
- Raspberry Pi Desktop on a laptop 4m 10s
- Programming with Node-RED 6m 15s
- Programming IoT with IFTTT 5m 24s
- Update the Raspberry Pi with apt-get 3m 3s
- A clean and simple web server 5m 23s
- Use SSH to control the Raspberry Pi 3m 28s
- Camera control with raspistill 4m
- GPIO pinout charts 3m 53s
- Back up the Raspberry Pi 3m 1s
- Use SmartSim to explore logic circuits 4m 47s
- Raspberry Pi 4 6m 29s
- Change your default password 2m 44s
- Mathematica and general-purpose input/output (GPIO) 6m 7s
- Build a Raspberry Pi private cloud 8m 40s
- Dealing with undervoltage 3m 50s
- Play music with Sonic Pi 5m 53s
- Add a printer to Raspberry Pi 3m 38s
- Use Screenly for web kiosks 5m 59s
- Use raspivid for Raspberry Pi Videos 4m 55s
- Build an MQTT publisher 6m 33s
- Build an MQTT client 4m 5s
- Connect to MQTT with Node-RED 9m 55s
- Build an MQTT broker 4m 44s
- A power switch for the Raspberry Pi 3m 57s
- Input polling vs. interrupts 5m 41s
- GPIO Pi headers 2m 34s
- High-grade audio for the Raspberry Pi 4m 34s
- Program the Sense HAT with Node-RED 6m 54s
- Remote GPIO 6m 5s
- Framboisedorf 4m 6s
- Use Kano OS 5m 15s
- What's new with Scratch 3.0? 2m 57s
- Controlling high voltages with the Raspberry Pi 4m 53s
- Rotary phone: Intro and switches 3m 12s
- Rotary phone: Ringer 2m 44s
- Rotary phone: Speaker 5m 28s
- Piscope 5m 33s
- Cron on the RPI 7m 45s
- Keep your plants watered with a Raspberry Pi 4m 42s
- Grove HAT 4m 45s
- Build a door cam with a Raspberry Pi 4m 4s
- Explore the Sense HAT emulator 3m 49s
- Use a hard drive with the Raspberry Pi 3m 33s
- Build a temperature-controlled fan for the Raspberry Pi 4 6m 59s
- Run COBOL on a Raspberry Pi 4m 12s
- Adafruit IO 7m 41s
- Overclocking the Raspberry Pi 7m 4s
- The boot directory and config.txt 7m
- Field connection to the Raspberry Pi 6m 30s
- Rotary phone: Microphone hardware 4m 34s
- Rotary phone: Microphone software 5m 47s
- Raspberry Pi 12-megapixel camera 7m 27s
- Text to speech on a chip 5m 44s
- Connect GPS to the Raspberry Pi 7m 47s
- Minecraft and GPIO 5m 11s
- Raspberry Pi Pico 5m 31s
- Use libgpiod instead of sysfs 9m 51s
- Revisiting adding a printer to Raspbian 3m 50s
- Revisiting a temperature controlled fan 4m 26s
- Run R on a Raspberry Pi 7m 35s
- Another motion-activated camera 4m 49s
- Ubuntu desktop 4m 38s
- A web interface to a camera 5m 53s
- Use systemd to start programs at boot 6m 55s
- Find the IP address of your Raspberry Pi 5m 2s
- Contribute to community computing 4m 6s
- BBC BASIC on the Raspberry Pi 4m 25s
- Capacitive touch sensor 3m 35s
