[FE training-materials-updates] kernel labs: clarify nunchuk setup

[Alexandre Belloni]

Repository : git://git.free-electrons.com/training-materials.git

On branch  : master
Link       : http://git.free-electrons.com/training-materials/commit/?id=b88f64a9e536e4816d2c6bde9515ff7278f18b63

>---------------------------------------------------------------

commit b88f64a9e536e4816d2c6bde9515ff7278f18b63
Author: Alexandre Belloni <alexandre.belloni at free-electrons.com>
Date:   Mon Oct 28 23:35:58 2013 +0100

    kernel labs: clarify nunchuk setup
    
    Signed-off-by: Alexandre Belloni <alexandre.belloni at free-electrons.com>


>---------------------------------------------------------------

b88f64a9e536e4816d2c6bde9515ff7278f18b63
 .../kernel-i2c-communication.tex                   |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/labs/kernel-i2c-communication/kernel-i2c-communication.tex b/labs/kernel-i2c-communication/kernel-i2c-communication.tex
index 399b14f..22b1415 100644
--- a/labs/kernel-i2c-communication/kernel-i2c-communication.tex
+++ b/labs/kernel-i2c-communication/kernel-i2c-communication.tex
@@ -105,14 +105,14 @@ In the probe routine (run every time a matching device is found):
 \begin{enumerate}
 \item Using the I2C raw API (see the slides), send two bytes to the
       device: \code{0xf0} and \code{0x55}
-      \footnote{Your instructor supplied a white nunchuk to you, but you
-      can see that in
-      \url{http://web.engr.oregonstate.edu/~sullivae/ece375/pdf/nunchuk.pdf},
-      this initialization sequece corresponds to the so-called "black"
-      nunchuk. Apparently, the "black" and "white" models mentioned in
-      this document correspond to different versions originally sold
-      under the Nintendo brand. Our model is a generic implementation,
-      which apparently replicates the "black" one from Nintendo.}.
+      \footnote{There are two ways of communicating with a wiimote extension.
+        The first known way was with data encryption by writing the encryption
+        byte 0x00 to 0x40. With this way, you have to decrypt each bytes you
+        read from the nunchuk (not so hard but something you have to do).
+        Unfortunately, using 0x00 as the encryption byte is not working on third
+        party nunchuks so you have to set up unencrypted communication by
+        writing 0x55 to 0xF0, then writing 0x00 to 0xFB. This is working across
+        all brands of nunchuks (including Nintendo ones).}.
       Make sure you check the return value of 
       the function you're using. This could reveal communication issues.
       Using LXR, find examples of how to handle failures properly using