DarkPlatinum
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How to decrease amperage required my Pi 3?

Sat Nov 10, 2018 6:34 pm

Hello all, I have setup a flight tracker with PiRadar24 software on Raspbian Stretch on a Raspberry Pi 3.

I plug in the DVB-t dongle, it is recognized by te software plus in lsusb. After 15-20 minutes, i come back to check on the feed status and it says reciever is down. I check lsusb and the dongle is no longer there.

https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

EDIT: I have ordered a 3 amp supply to counter the above problem. i was wondering what is the best way to suffice for now? I have disabled bluetooth since that takes a tad bit of amperage. Does anyone else have tips?
Last edited by DarkPlatinum on Sun Nov 11, 2018 8:02 pm, edited 1 time in total.
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DirkS
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Re: USB input disappears

Sat Nov 10, 2018 8:29 pm

Check the log for USB errors (use e.g. dmesg).
Also have a lookout for undervoltage messages, etc.

There's a good chance it's a power problem. These dongles can be quite power hungry at times.

DarkPlatinum
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Re: USB input disappears

Sat Nov 10, 2018 8:38 pm

DirkS wrote:
Sat Nov 10, 2018 8:29 pm
Check the log for USB errors (use e.g. dmesg).
Also have a lookout for undervoltage messages, etc.

There's a good chance it's a power problem. These dongles can be quite power hungry at times.
My dmesg says undervoltage then somewat soon it says stabilised. Im using a 2.5 amp power supply, and not a thin cable. My power supply is fine it seems, it does undergoe undervoltage during boot up but thats pretty normal since boot requires more amperage i guess? :P

I switched the dongle to a different USB port and it seems to work ok for now. I do experience undervoltage:

[ 135.271003] Voltage normalised (0x00000000)
[ 307.914242] rpi_firmware_get_throttled: 6 callbacks suppressed
[ 307.914249] Under-voltage detected! (0x00050005)
[ 339.114891] Under-voltage detected! (0x00050005)
[ 345.354997] rpi_firmware_get_throttled: 7 callbacks suppressed
[ 345.355004] Voltage normalised (0x00000000)
[ 368.235301] Under-voltage detected! (0x00050005)
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PeterO
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Re: USB input disappears

Sat Nov 10, 2018 9:00 pm

How do you reconcile
DarkPlatinum wrote:
Sat Nov 10, 2018 8:38 pm
My dmesg says under voltage
and
My power supply is fine it seems,
When clearly
My dmesg says under voltage
means
My power supply is fine it seems,
is not the case.

You have no way of knowing if the under voltage has had any effect on the circuits in the dongle.
PeterO
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DarkPlatinum
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Re: USB input disappears

Sat Nov 10, 2018 9:13 pm

PeterO wrote:
Sat Nov 10, 2018 9:00 pm
How do you reconcile
DarkPlatinum wrote:
Sat Nov 10, 2018 8:38 pm
My dmesg says under voltage
and
My power supply is fine it seems,
When clearly
My dmesg says under voltage
means
My power supply is fine it seems,
is not the case.

You have no way of knowing if the under voltage has had any effect on the circuits in the dongle.
PeterO
lol, yes I make no sense :lol: I ordered a 3A power supply just now.
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HawaiianPi
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Re: USB input disappears

Sun Nov 11, 2018 1:51 am

You should get the official Raspberry pi Universal power Supply. It's a proven performer and is usually very affordable (depending on where you are, and who you buy it from).

A lot of so-called "power supplies" for single board computers are really re-purposed phone chargers, and some of those have poor voltage regulation (because charging batteries does not require precise voltage control). In addition to that, if the PSU uses a separate micro USB cable that can cause more problems, as standard micro USB 2.0 cables often can't deliver much more than 500mA (which is the USB 2.0 power spec) without significant voltage loss.

USB devices are particularly sensitive to voltage droops. The Pi itself will run at voltages well under 5V, and the red power good LED won't turn off until the voltage drops below 4.65V, while the USB power spec is 5V +/- 5% (4.75V - 5.25V).

The official PSU outputs 5.1V at up to 2.5A and has a beefy built-in 18 AWG power cable.
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DarkPlatinum
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Re: USB input disappears

Sun Nov 11, 2018 1:50 pm

Yes I have one of them, but using it with my other raspberry pi. It can get a bit expensive just buying power supplies, so i opted for a cheaper one from here: https://www.ebay.co.uk/itm/DC-5V-3A-Mic ... 2749.l2649
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DarkPlatinum
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Re: USB input disappears

Sun Nov 11, 2018 7:33 pm

Does anyone have any tips for decreasing the amperage required by a Pi 3? Just want to see if this will work since the power supply i order says it will come within 2-3 weeks. I currently have downclocked te pi to 800mhz in boot/config.txt, and it seems that it has dropped the requirement in amperage a bit. (Dongle takes longer to go offline)

I do not have a HDMI cable or anything else plugged in apart from power cable and the USB DVB-t dongle. Ill disable bluetooth soon, hopefully it helps a wee bit.
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Imperf3kt
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 8:58 pm

Disabling the LAN chip should greatly reduce power consumption
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

DarkPlatinum
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 9:19 pm

Imperf3kt wrote:
Sun Nov 11, 2018 8:58 pm
Disabling the LAN chip should greatly reduce power consumption
But I need wifi though.
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drgeoff
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 9:27 pm

DarkPlatinum wrote:
Sun Nov 11, 2018 9:19 pm
Imperf3kt wrote:
Sun Nov 11, 2018 8:58 pm
Disabling the LAN chip should greatly reduce power consumption
But I need wifi though.
The onboard Wi-Fi of a 3B or 3B+ is not dependent on the LAN&USB chip.

DarkPlatinum
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 10:51 pm

drgeoff wrote:
Sun Nov 11, 2018 9:27 pm
DarkPlatinum wrote:
Sun Nov 11, 2018 9:19 pm
Imperf3kt wrote:
Sun Nov 11, 2018 8:58 pm
Disabling the LAN chip should greatly reduce power consumption
But I need wifi though.
The onboard Wi-Fi of a 3B or 3B+ is not dependent on the LAN&USB chip.
Oh. If I disabled the LAN chip, is that disabling the USB ports? I need a USB port for the USB ads b reciever.
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Imperf3kt
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 10:55 pm

IIRC, the LAN chip is separate to the USB hub - it just runs off the same power rail and I/O bus. I may be wrong though, I haven't researched this too much yet.

I've been thinking of trying this for a while myself, but haven't yet got into trying.
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

DarkPlatinum
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Re: How to decrease amperage required my Pi 3?

Sun Nov 11, 2018 11:01 pm

Imperf3kt wrote:
Sun Nov 11, 2018 10:55 pm
IIRC, the LAN chip is separate to the USB hub - it just runs off the same power rail and I/O bus. I may be wrong though, I haven't researched this too much yet.

I've been thinking of trying this for a while myself, but haven't yet got into trying.
Does the LAN chip just run the Ethernet port?
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DougieLawson
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Re: How to decrease amperage required my Pi 3?

Mon Nov 12, 2018 1:14 am

DarkPlatinum wrote:
Sun Nov 11, 2018 11:01 pm
Imperf3kt wrote:
Sun Nov 11, 2018 10:55 pm
IIRC, the LAN chip is separate to the USB hub - it just runs off the same power rail and I/O bus. I may be wrong though, I haven't researched this too much yet.

I've been thinking of trying this for a while myself, but haven't yet got into trying.
Does the LAN chip just run the Ethernet port?
The SMSC9514 is both the LAN & the USB you can't disable one without killing both.
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Imperf3kt
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Re: How to decrease amperage required my Pi 3?

Mon Nov 12, 2018 2:06 am

Oh, well that's a bit of a shame. I had hopes for that myself.

Can it be replaced with a different chip perhaps? For example one of these?
https://au.element14.com/texas-instrume ... csku=false
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

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rpdom
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Re: How to decrease amperage required my Pi 3?

Mon Nov 12, 2018 6:02 am

Imperf3kt wrote:
Mon Nov 12, 2018 2:06 am
Oh, well that's a bit of a shame. I had hopes for that myself.

Can it be replaced with a different chip perhaps? For example one of these?
https://au.element14.com/texas-instrume ... csku=false
If you only need one USB port, you could possible (if you have the required skills), remove the USB/LAN chip and hook a USB port up directly to the SoC. Essentially you'd be making a Pi3A as that is what the main difference between the Pi 1B and Pi 1A was.

DarkPlatinum
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Re: How to decrease amperage required my Pi 3?

Mon Nov 12, 2018 7:42 am

rpdom wrote:
Mon Nov 12, 2018 6:02 am
Imperf3kt wrote:
Mon Nov 12, 2018 2:06 am
Oh, well that's a bit of a shame. I had hopes for that myself.

Can it be replaced with a different chip perhaps? For example one of these?
https://au.element14.com/texas-instrume ... csku=false
If you only need one USB port, you could possible (if you have the required skills), remove the USB/LAN chip and hook a USB port up directly to the SoC. Essentially you'd be making a Pi3A as that is what the main difference between the Pi 1B and Pi 1A was.

The reason why I'm trying to decrease amperage is because I've gotta wait a couple of weeks before the power supply arrives.
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