geoffcox
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re my keyboard problem

Sun Jul 01, 2012 6:00 am

Hello

I have just been out and spent £27 on a usb keyboard, Logik Ultra Slim Keyboard LKBWSL11 and a usb hub, LOGIK LP4HUB10 - both of which are on the RPi Verified Peripherals list as being OK.

I am using a Trust usb optical mouse, formally called USB Optical Mouse MI-2275F.

I am using an HDMI - DVI cable to my computer monitor.

I am using the power supply which came with the Raspberry Pi from RS Components.

How do I see the power supply reading from tp1/tp2?

..and still cannot type anything from the keyboad ... although I have managed this twice but can no longer do this! It originally worked with only the keyboard attached and when I rebooted with the mouse added I could not used the keyboard. I rebooted without the mouse and then could not use the keyboard!

Thoughts?!

Geoff

Steep
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Re: re my keyboard problem

Sun Jul 01, 2012 9:19 am

To measure the voltage across TP1/2 you need a multimeter set to DC volts, ideally it should not measure over 5.2v and should not drop too much below 5v under load (that's with everything plugged in and the RPI booting up). Measure the voltage with the SD card out so the RPi does not boot and with nothing else plugged in to get a reading of the no load voltage. Try again with the SD card only in, you should see a drop in voltage, do the same adding one item at a time and as long as the voltage does not drop too far you'll have shown that the power supply is good and can supply enough.
I had a supposedly good psu rated at 2amps, under load the voltage output from it dropped to nearly 4.8v from the initial 5.21 and this caused problems with my keyboard typing odd characters.

geoffcox
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Re: re my keyboard problem

Sun Jul 01, 2012 10:20 am

thanks for your reply - but where do I find tp1 and tp2?!

Geoff

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rurwin
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Re: re my keyboard problem

Sun Jul 01, 2012 10:29 am

They are labelled on the board. TP2 is nestled between the GPIO and the audio socket, and TP1 is about a centimetre under the raspberry logo.

Bad Wolf
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Re: re my keyboard problem

Sun Jul 01, 2012 10:30 am

Tp1 is located just below the Raspberry Pi logo
TP2 is located next to the yellow composite output


ARRRG rurwin got there first!
Great minds think alike!
To a person with a hammer, everything looks like a nail.

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rurwin
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Re: re my keyboard problem

Sun Jul 01, 2012 12:38 pm

:-D at least you identified the composite socket right. I was going by my printed PCB rather than bothering to open the box to check the real thing.

Steep
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Re: re my keyboard problem

Sun Jul 01, 2012 6:16 pm

And just to help identify them, they are the little holes with shiny metal and 4 white minus signs around them in this picture http://www.raspberrypi.org/wp-content/u ... 365272.jpg

Bigally
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Re: re my keyboard problem

Sun Jul 01, 2012 6:54 pm

Please see http://www.raspberrypi.org/phpBB3/viewt ... =28&t=8387 as the problem is discussed in some detail, viz a problem with X1 controlling the USB port.

geoffcox
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Re: re my keyboard problem

Sun Jul 01, 2012 7:03 pm

Thanks for the signposts - in fact I googled and found a photo showing the meter attached to TP1 and 2.

I still cannot get the keyboard to work!

The voltages are as follows

with power supply and SD card - 4.99 V
as above + HDMI - DVI cable - 4.99 V
as above + keyboard attached directly to Pi - 4.96 V
as above but with keyboard attached via the USB hub - 5 V
as above plus mouse attached via hub - 4.99 V

The card came from RS Components with Debian GNU/Linux 6.6

The voltages seem OK? So where do I go next?

Cheers

Geoff

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mahjongg
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Re: re my keyboard problem

Sun Jul 01, 2012 7:56 pm

Use TP2 connect the black lead of our multimeter to GND of the board, and with the red lead measure on both sides of the green polyfuses located between the LEDs, and the USB port.
Essentially on one end you will find the same 4.9 V voltage as on TP1 but on the other end you will find a lower voltage (if the USB port the polyfuse is connected to draws any current from an USB device), that end will be slightly lower, at say 4.5 Volt, if its lower than 4.4 Volt your USB device won't work.

You can also measure between the pins of the polyfuse to see how much voltage fall over them, or with the PI turned off you could measure the resistance of the polyfuse (remove anything from the USB connectors before you do) The drop across the polyfuse should be less than say 0.5 Volt, and the resistance should be something like 5 Ohm, if the drop, or the resistance is much more you have identified your problem as that polyfuse. If so it means it has "seen" a short circuit, but will recover in time (days).

geoffcox
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Re: re my keyboard problem

Sun Jul 01, 2012 8:08 pm

sorry - is TP2 the GDN?

Geoff

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Re: re my keyboard problem

Sun Jul 01, 2012 8:11 pm

Yes, TP2 is the GND (ground) pin, and TP1 is the +5V (after the input polyfuse) pin.

geoffcox
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Re: re my keyboard problem

Sun Jul 01, 2012 8:33 pm

I see 3 objects between the LEDs and the USB sockets - the 2 outer ones in the line have the number 14 on them and the one in the middle has 47?/10V on it.

The one nearest the edge of the board has 5V on one side and 5.13V on the other. The other, with the number 14 on it has 5V on either side.

??!!

Geoff

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mahjongg
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Re: re my keyboard problem

Sun Jul 01, 2012 10:05 pm

well yes, if you reference this picture Image then the two green ones with X14 on them are the polyfuses, The "X" is actually a manufacturers logo, and "14" stands for 0.14A or 140mA.
These are the ones.
The yellow device is actually a capacitor 47uF 10V which stores some electrical power so the power supply doesn't dip when you plug in a USB device (which normally also has a capacitor, which is empty when you plug the USB in, so it would temporarily cause a voltage dip if it wasn't for the 47uF elco to safe the day). The elco you can ignore, its only the polyfuses we are interested in.

If you have one polyfuse (its not actually clear from your description) which actually has a higher value on it on one end than what is on the PI (TP1) itself, then it means that the HUB is actually attempting to put power back into the PI!
What I'm looking for is what happens when you do not connect the hub, but directly connect the USB keyboard to the PI, and then measure what is on the same side of the Polyfuse that you saw the 5.13 volt on (if you actually measured 5.15 V on a polyfuse lead then was it on the lower side or the top side of the polyfuse, I would like to know).

Also if you have an Ethernet cable ready (connected to your ethernet modem) plug it in to the (powered) RPI, and check if any of the ethernet LEDs start to burn, if not the "keyboard problem" might actually be a problem with the LAN9512 chip, which contains an USB hub, and Ethernet device. Some people have no ethernet, and no USB (checked with a serial connection) caused by a bad Crystal (X1) tapping it, or shocking it with cold or heat (soldering it) can get it going.

geoffcox
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Re: re my keyboard problem

Mon Jul 02, 2012 10:27 am

Looking at my attached diagram - with the keyboard directly connected to the Pi,

a is 4.95V
b is 4.95 V (and this had the 5.13V when using the hub)

c is 4.95V
d is 4.2/3 V

Re your suggestion about the ethernet cable - I'm not too keen to have smoke coming from the LEDs!

Cheers

Geoff
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Re: re my keyboard problem

Mon Jul 02, 2012 11:24 am

a and c are where the 5v arrives at the fuses, and is ok at 4.95V
b is the power out to the top USB port, and nothing's connected to it
d is the power out to the bottom port, and at 4.2 is too low - your keyboard is taking too much current through that fuse.

geoffcox
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Re: re my keyboard problem

Mon Jul 02, 2012 11:37 am

apologies - I got that wrong.

c is 4.95V
d is 4.93V

with the keyboard attached directly to the USB socket so the keyboard seems OK.

still not able to enter text though .....

Geoff

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Re: re my keyboard problem

Mon Jul 02, 2012 11:52 am

Hmm. That says power isn't the problem.
Straw clutching time.
Does the keyboard have LEDs (caps-lock, etc.) and do they light? If it does and they do then the keyboard is getting power, but if not it could still be doing so - those light only when told to by the Pi.
Does the mouse light its light? Can you swap mouse and keyboard?

Otherwise it seems to be a software problem?

geoffcox
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Re: re my keyboard problem

Mon Jul 02, 2012 12:42 pm

the keyboard LEDs work when it is connected to my Windows 7 PC but not when connected to Pi.

The mouse does light its light with Pi.

I swopped mouse/keyboard but still unable to enter text.

The software is the Debian v6 which came installed on the SD card I bought from RS Components.

Do I need to provide my own version? If yes, which should I go for and where would I get it from?

Cheers

Geoff

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Re: re my keyboard problem

Mon Jul 02, 2012 3:27 pm

It might be a problem with the usb port controller as discussed in the link posted by bigally ^ it might also just be your keyboard (have you tried it on another machine?) or a software problem. For example in Debian Squeeze, when I first install it my keyboard works fine at the command prompt and in lxde, but as soon as I run updates the keyboard stops working in lxde.

geoffcox
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Re: re my keyboard problem

Mon Jul 02, 2012 10:04 pm

The keyboard works OK on my Windows PC. The annoying thing is that twice I have had the keyboard working! Not now though ....

Can I overwrite the Debian OS on the SD card which came, with the OS installed, from RS Components?

Geoff

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mahjongg
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Re: re my keyboard problem

Tue Jul 03, 2012 8:23 am

If I read your post right, then on one polyfuse there is absolutely no difference between one pin of the polyfuse, and the other (both 4.95V), and on the other only 0.03 or 0.02 volt (difference between 4.95 and 4.92 or 4.93 volt) .

That would indicate that almost no current is flowing through neither polyfuse, which is also indicative of a failure! At a minimum F1 and F2 would have something like 3 Ohms of resistance, for just 0.03 volt drop this means that just I= U/R = 0.03 / 3 = 10mA max is flowing through the keyboard, that is a suspiciously low amount. Normally I would expect something like 50 or 60 mA.
For a drop across the polyfuse of something like 0.3 Volt, not 0.03 Volt. If the voltage creeps above 0.6V (that is a voltage below 4.4 Volt after the polyfuse), then the keyboard would get too little voltage, but this result is more indicative of the keyboard getting no power (and thus drawing no current).

It would be logical to assume that the lower pin of the polyfuse is connected to the USB port, so at least that part of your measurements seems logical.

Could still be simple measuring errors though.

I agree with testing if the capslock can be toggled is a good connectivity test, as its the PI who reads the capslock key, and its the PI who commands the capslock LED to turn on.
If you can toggle the capslock on off there should be a working USB system.

Do you have a working ethernet connection, (with working I mean an active ethernet cable, connected to an ethernet hub, or modem). What do you see if you plug the ethernet cable into the PI's ethernet port. If the LAN9512 (ethernet & usb-hub chip) is working you should see ethernet status lights light up, if not you may have a PI with a defective LAN9512 chip, or rather a chip with a 25MHz crystal that starts unreliably.

geoffcox
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Re: re my keyboard problem

Tue Jul 03, 2012 9:55 am

re ethernet - where do I see any status light? the router/modem does not have separate light for each ethernet connection (its an O2 Technicolor wireless box 5) - is there one on the Pi itself?

Cheers

Geoff

geoffcox
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Re: re my keyboard problem

Tue Jul 03, 2012 10:03 am

in fact it looks as if the ethernet connection to Pi may be working as when I boot it up with the ethernet cable connected, the one and only ethernet LED on the router/modem does flash several times ...

am I right?

Geoff

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Re: re my keyboard problem

Tue Jul 03, 2012 10:25 am

On your Pi, the LEDs labelled "FDX","LNK" & "10M" should show some signs of life.

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