ltorvalds024
Posts: 6
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Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 1:40 pm

Official documentation says:

Typically, the model B uses between 700-1000mA depending on what peripherals are connected; the model A can use as little as 500mA with no peripherals attached. The maximum power the Raspberry Pi can use is 1 Amp. If you need to connect a USB device that will take the power requirements above 1 Amp, then you must connect it to an externally-powered USB hub

That means I can connect any device that uses 5V and current less than 1A.
Why cant I connect my external hard drive that operates at 5V and consumes less than 500mA (this is the maximum current USB 2.0 can provide) ?

I am using Raspberry Pi 2 and Raspbian as OS

NOTE: I am only connecting the power source (that can provide more than 1A) and a Ethernet cable
Last edited by ltorvalds024 on Mon Nov 09, 2015 2:01 pm, edited 1 time in total.

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RaTTuS
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Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 1:53 pm

you probably can
see adding
max_usb_current=1
to the correct config.txt file which will up the current to a max of 1.2A on all 4 ports
what does dmesg say when you plug this hard disk in

if you are using a model b [old school] not b+ or b2 then other things may be needed to make it work
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fruitoftheloom
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Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 1:54 pm

Removed as OP stated RPi B not 2B
Last edited by fruitoftheloom on Mon Nov 09, 2015 2:03 pm, edited 1 time in total.
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fruitoftheloom
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Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 1:55 pm

Removed as OP stated RPi B not 2B
Last edited by fruitoftheloom on Mon Nov 09, 2015 2:04 pm, edited 1 time in total.
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ltorvalds024
Posts: 6
Joined: Mon Oct 19, 2015 2:29 pm

Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 2:02 pm

RaTTuS wrote:you probably can
see adding
max_usb_current=1
to the correct config.txt file which will up the current to a max of 1.2A on all 4 ports
what does dmesg say when you plug this hard disk in

if you are using a model b [old school] not b+ or b2 then other things may be needed to make it work
I am using Raspberry Pi 2 and Raspbian as OS, where can I find these settings?

fruitoftheloom
Posts: 24448
Joined: Tue Mar 25, 2014 12:40 pm
Location: Delightful Dorset

Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 2:05 pm

ltorvalds024 wrote:
RaTTuS wrote:you probably can
see adding
max_usb_current=1
to the correct config.txt file which will up the current to a max of 1.2A on all 4 ports
what does dmesg say when you plug this hard disk in

if you are using a model b [old school] not b+ or b2 then other things may be needed to make it work
I am using Raspberry Pi 2 and Raspbian as OS, where can I find these settings?
This applies to RPi1 B+ & RPi2 B

https://projects.drogon.net/testing-set ... berry-pi-b


https://www.raspberrypi.org/help/faqs/#power
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RaTTuS
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Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 2:08 pm

;)
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
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PiBrain
Posts: 3
Joined: Mon Nov 09, 2015 12:58 pm

Re: Why cant I connect external hard drive with USB 2.0?

Mon Nov 09, 2015 2:09 pm

ltorvalds024 wrote:
RaTTuS wrote:you probably can
see adding
max_usb_current=1
to the correct config.txt file which will up the current to a max of 1.2A on all 4 ports
what does dmesg say when you plug this hard disk in

if you are using a model b [old school] not b+ or b2 then other things may be needed to make it work
I am using Raspberry Pi 2 and Raspbian as OS, where can I find these settings?
I think what you're looking for is the file /boot/config.txt. Usually caution about editing system files and making backups apply.

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