possible solution for RPi USB hot plug problems

Or alternatively as mahjongg says, replace the two badly-specced USB polyfuses by ones with higher trip points as we said some weeks ago, so that they also have lower resistances.  That'll also stop the polyfuses making the USB Vcc drop out of spec so rapidly for power-hungry peripherals, so you kill two birds with one stone.

This whole power management design saga is pretty funny.  The moral is, don't throw away several decades' worth of regulated supply practice just to save some pennies.  Toss the CSI/DSI connectors overboard first if you need a sacrifice.

Morgaine.

Amen.

I'm still trying to figure in which mind was that having those connectors was a good idea. I don't envision a large percentage of the R-Pi community ever use them.

IMHO the entire power design on the R-Pi is flawed, plus to cut costs built with cheap knock-off components like the LDO's.

I guess somebody was shopping on alibaba when they were putting together the BOM.

-J

Jamodio,

First of all the RPi is not made for most purposes the community uses it for.

Officially it is created and designed for educational use. In education use these headers are usefull for expansion.

And what is the problem with the LDO? I see no problems with them they are used in many designs without any problems, the USB should be used with keyboard and a mouse only and not for USB drives and so on.

As stated earlier external storage should be powered through a USB HUB with external power supply.

Sure, good for you. Read the "official" instruction manual ...

-J

Marco,

you wrote:

> First of all the RPi is not made for most purposes the community uses it for.

> Officially it is created and designed for educational use

I think "Officially" the current product is being sold for unrestricted use, and

a future version is planned for educational use.

>the USB should be used with keyboard and a mouse only and not for USB drives and so on.

I think the USB ports are being advertised as unrestricted USB 2.0 ports. 

If they were 1.1, then I could maybe understand a keyboard/mouse restriction,

but USB 2.0 ports are normally intended for USB drives, WiFi dongles, and

all sorts of other things.

The RPi is demonstrated with some sort of USB stick or drive here:

http://connecteddigitalworld.com/2012/03/26/a-slice-of-raspberry-pi-at-beeb30/

The official RPi FAQ also says using a keyboard with built-in USB hub would

"work well", but that has turned out to be troublesome:

    "How do you connect more than two USB devices?

     Use a hub to increase the number of ports. Some keyboards have hubs built in which would work well."

http://www.raspberrypi.org/faqs

Even keyboards with LEDs and backlighting have turned out to be

unexpectedly troublesome. 

Hopefully there will be a solution soon.

Otherwise, if there are restrictions on USB devices, the documentation

should be updated to clearly indicate such restrictions.

Currently, the official RPi User's Guide says on page 3 of 5:

"4. Plug your extras into the Pi. (USB WiFi, Ethernet cable, hard drive, etc).

  This is where you may really need a USB Hub."

http://www.element14.com/community/docs/DOC-43088/l/raspberry-pi-quick-user-guide-for-raspberry-pi-single-board-computer?ICID=rasp_group

The implication is that the hub may be needed only due to running out of ports,

since it explicitly says to plug the "hard drive" "into the Pi".

The RPi User's Guild also says on page 3:

"Most standard USB keyboards and mice will work with the RPi."

Are modern keyboards with LEDs or built-in hubs considered non-standard?

The sentence that follows implies that non-standard refers only to wireless.

Marco de Grauw wrote:

 

Officially it is created and designed for educational use.

Raspberry Pi was certainly created to assist in IT education (or at least it's alleged), but it wasn't designed for it.  It was designed around the Broadcom BCM2835, a powerful multimedia and DSP device with a tiny and rather old ARM1176 core stuck in a corner to handle some admin duties which would have been more expensive to handle in silicon.

The BCM2835 certainly wasn't designed as a computing device, and consequently nor was the Pi.  The board is going to be very useful for IT education (with a bit of luck) because of its very low price, but don't confuse utliity with design for purpose.  If it had been designed to be an IT machine for eduication it would look very different.

Morgaine.

Marco de Grauw wrote:

 

Officially it is created and designed for educational use.

Raspberry Pi was certainly created to assist in IT education (or at least it's alleged), but it wasn't designed for it.  It was designed around the Broadcom BCM2835, a powerful multimedia and DSP device with a tiny and rather old ARM1176 core stuck in a corner to handle some admin duties which would have been more expensive to handle in silicon.

The BCM2835 certainly wasn't designed as a computing device, and consequently nor was the Pi.  The board is going to be very useful for IT education (with a bit of luck) because of its very low price, but don't confuse utliity with design for purpose.  If it had been designed to be an IT machine for eduication it would look very different.

Morgaine.