Re: 12V Power for the Pi (was Re: [RaspberryPi-4-HamRadio] Getting back to the RPi)

David Ranch
 


The thought about checking your power connection (Y cables, etc) from N9VPV was a very important one.  Even with a good power supply, if your power cables are too thin, too long, or both.. you're going to have power issues when the Rpi needs to draw more current as the voltage drop will upset it.  Maybe the PowerWerx USB-buddy can supply your needed current and do so RF quietly but it could be the power cables before and after that unit are letting you down.  Try beefing up the gauge of the wire and shorten the cables and maybe your Rpi "lightening" bolt issues will go way.

As to the Rpi powering ideas, google "raspberry pi USB hatt".  There are a LOT of them out there but the question is if they are RF quiet.  The impressive TARPN project from KA2DEW  has a lot of Raspberry Pi units running for a long time so if he gives it the nod of acceptance, I bet it's a safe bet but just be careful on the cooling.  There are other similar products out there as well such as this one:

   https://www.ebay.com/itm/Buck-Step-down-LM2596-Power-Converter-Module-DC-4-0-40-to-1-3-37V-LED-Voltmeter/222514124788

I have one of these but I haven't put it under enough stress to give it any recommendations just yet.


Btw.. if you want to monitor the status of the voltage issues on your Raspberry Pi when HEADLESS, this script can get you that detail and a lot more.  It's a bit complicated to decipher the bitmask but that's how the Broadcom chip presents all of it.  Once you get used to it, it's not bad.  You can also just look at the content of the script to give you ideas of how to do things your way.


http://www.trinityos.com/HAM/CentosDigitalModes/RPi/usr/local/bin/review-rpi-cpu.sh
--
review-rpi-cpu.sh : Read the script comments for lots of helpful details and URL on specific areas


CPU / GPU Memory split
arm=896M             
gpu=128M             

View count of any previous power under-voltage or over-temp events:


   Example: for a 0x50005 result, the different bit values translate to:
        0: currently under-voltage          : occurs when input voltage drops below 4.63V
        1: currently arm frequency capped   : occurs with temp > 80'C
                                            : over-temperature occurs with temp > 85'C
        2: currently throttled (any reason from above)
       16: under-voltage has occurred in the past
       17: arm frequency capped has occurred in the past
       18: throttling has occurred in the past

Read value:
throttled=0x0

Translation
bit
1111111110000000000
8765432109876543210
-------------------
0

Current CPU speed govrenor: (valid is 'powersave', 'ondemand'): ondemand

Current CPU frequency: 600000

Max allowed frequency: 1200000

SOC Temp (in Celsius) - DD.ddd -- throttling begins at 80C: 41856
Temp in C: 41.85
Temp in F: 107.33

GPU temp: temp=41.9'C

Rpi Serial number, model firmware and Waranty bit (MSB):
Serial          : 00000000585fxxxx
Revision        : a22082
   Example:
      revision value of 9000c1 is Pi 0 Model W   - 512MB
      revision value of   000f is Pi 1 Model B   - 512MB
      revision value of a21041 is Pi 2 Model B   -   1GB - made at Embest, China
      revision value of a22082 is Pi 3 Model B   -   1GB - made at Embest, China
      revision value of a020d3 is Pi 3 Model B+   -  1GB

Broadcom firmware version:
Aug 15 2019 12:08:48
Copyright (c) 2012 Broadcom
version 0e6daa5106dd4164474616408e0dc24f997ffcf3 (clean) (release) (start_x)

Max CPU clock confirmation: system will clock up to max CPU speed (turbo mode) by loading the CPUs and then report new CPU frequency
1200000

Done
--



On 12/24/2019 08:35 AM, Michael WA7SKG wrote:
Dan,

THANK YOU! What a device! While you say expensive, it's only a few dollars more than the USBuddy and does so much more. The on/off switch is a big plus, as well as the HAT configuration. The only thing I'm not sure of is powering the monitor as well. As I am using the Smarti-Pi Touch Case, the RPi is not mounted directly to the monitor, so it is not powered through the IO pins, but from a separate USB connection. However, I do not think this is insurmountable.

Thanks again.

73,
Michael WA7SKG

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