Oh I see now, exchanging info during exams could be pretty bad...

+-----------+
| Norse 1.0 |
+-----------+
by X. Andréani
http://www.ti-bank.fr/911 (link not active yet)


1) Introduction:
   ------------
A program to send and receive messages using the TI-Nspire LED.
Just type your message and it will be encoded into reg/green/yellow light signals.
The recipient just has to type the colors he/she sees and the message is decoded.


2) Hardware required:
   -----------------

* TI-Nspire (blue)
* TI-Nspire TouchPad (black & white)
* TI-Nspire CAS TouchPad (black)

The TI-Nspire CAS (grey) does not have the LED.
The program will run but nothing will be turned on.
Although, the TI-Nspire CAS has the LED circuit.
Just the LED is missing: you just have to solder one.


3) OS required:
   -----------

Any OS supported by a Ndless 1.7 compatible kernel.

As of this date:
- 1.3.2438    (non-CAS)   [Ndless 1.3]
- 1.3.2437   (CAS)      [Ndless 1.3]
- 1.4.11653   (non-CAS)   [Ndless 1.4]
- 1.4.11643   (CAS)      [Ndless 1.4]
- 1.7.2741    (CAS & non-CAS)   [Ndless 1.7 & Ndless 2.0]
- 2.0.1.60    (CAS & non-CAS)   [Ndless 2.0]


4) Software required:
   -----------------

Norse has been built for the Ndless 1.7 kernel.
You need Ndless 1.7, or a Ndless 1.7 compatible kernel.

As of this date, you'll need:
- Ndless 1.3 for OSes 1.3.2438  & 1.3.2437
- Ndless 1.4 for OSes 1.4.11653 & 1.4.11643
- Ndless 1.7 for OS   1.7.2741
- Ndless 2.0 for OSes 1.7.2741  & 2.0.1.60 (still in development)


5) Security:
   --------

In TI's Press-to-Test documentation, you can read:
<<The flashing LED is hardware-secure
and cannot be impacted by coded software>>

Seems the 2nd part of this sentence is a lie.
(TI's documentations have never been very
realiable for technical informations)

But the 1st part is partially true.
I don't know if it is hardware though, but there is
some kind of security on OSes 1.4 and newer.

On OSes 1.4 and newer, the LED is locked:
the writing to its memory I/O port is ignored.
So whatever you do with the program,
the LED state will remained unchanged.

On OSes 1.1 & 1.3, the LED is unlocked.
The program should work on the 1st try without any problem.
I assume the LED is unlocked in all OSes 1.1-1.3.


6) LED unlocking for OSes 1.4 and newer:
   ------------------------------------

On OSes 1.4 and newer it is possible to temporarily unlock the LED.

You just have to enable and disable Press-to-Test mode.
After disabling Press-to-Test mode,
the LED will be unlocked... untill the next reboot.

To enable PTT:
- turn off your calculator
- hold [Esc] and [Home] while turning the calculator on.
- a dialog box should be triggered: just validate with [Enter]
The calculator is now rebooting in PTT mode.

To disable PTT, you'll need one of the following:
* another TI-Nspire
* a computer
Just connect your calculator and choose the "Exit Press-to-Test"
option in the Tools menu ([Ctrl] [Home] with a ClickPad keypad).
The calculator is now rebooting in standard mode.
And the LED will remain unlocked after the reboot.

Note: This "bug" has only been tested only on OSes 1.4, 1.7 and 2.0.1.
I assume it is working with all OSes 1.4-2.1.
Now that it is public, TI may fix it in the next OS releases.


7) Main menu
   ---------

"Messages editor":
Lets you type a complete message and then send it,
and resend it if necessary.
The sending progress is shown on screen.

"Typewriter":
Each character you're typing is sent immediatly.
Usefull for short answers to yes/no questions or MCQ.

"Messages decoder":
Just type the colors seen on the remote calculator
and the message will appear on screen.

"Codes table"
Display the current encoding/decoding table with
all supported characters.

"Test LED"
Lets you test if the LED is locked.
Lets you test the 3 LED colors: red, green, yellow.


Norse code:
   ----------

The current version uses Norse code 1.0.

A character is coded by 1-3 color signals.

For each color signal, the DEL is turned on for 300ms.
Between color signals for the same character, the LED is turned off for 100ms.
Between words, the LED is turned off for 1000ms.

Character   |   Color signals
----------------+--------------------
space      |   aucun
-      |   YGY
.      |   YYR
0      |   GGG
1      |   GGY
2      |   GYR
3      |   GYG
4      |   GYY
5      |   YRR
6      |   YRG
7      |   YRY
8      |   YGR
9      |   YGG
A      |   Y
B      |   RGY
C      |   YY
D      |   YG
E      |   R
F      |   RGG
G      |   RYR
H      |   RYG
I      |   RR
J      |   RYY
K      |   GY
L      |   RRG
M      |   RY
N      |   YR
O      |   RRR
P      |   RGR
Q      |   GR
R      |   G
S      |   RG
T      |   GG
U      |   RRY
V      |   GGR
W      |   GRR
X      |   GRG
Y      |   GRY
Z      |   YYG


9) Cheating or not cheating:
   ------------------------

Norse has not been designed to cheat by exchanging informations during exams.
Remember cheating during exams is illegal.

Norse has been designed:

- to prove that it is possible to exchange complex
messages wirelessly with the Nspire LED

- to interest young people with encoding/decoding messages,
which is a very interesting branch of the mathematics

- to prove that TI's documentation is lying

- to prove that TI is very stupid
(the LED they added especially for the exams "could" be used to cheat during those same exams...)

- to help teachers designing new kind of activities for their students:
in typewriter mode, the LED can be used to quickly answer Yes/No questions or MCQs.

Anyway:
* it is very hard to find OSes 1.3 and older online
* the latest TI 2.x OSes are forbidding downgrades to the oldest 1.x OSes
* according to TI, there is no way for you to exit PTT mode during
an exam as you shouldn't be able to connect your calculator to another
calculator or a computer during an exam.


10) Licence:
   -------

GPLv2. Source code is included.
You may modify the source code according to the included
licence, but I'm just asking one more thing:

- If you do change something with the encoder/decoder, please keep
decoding compatibility with messages encoded with this version.
- If you do not keep this compatibility, please do not pretend to
use "Norse" code any more.


11) Known problems/bugs:
    -------------------

* Random reboots while (or after) using the program
when the LED is locked. It may not be a bug in the program...
It might be a Ndless 1.7 bug, or another protection from TI.


12) Release history:
    ---------------

27.12.2010:   1.0 - initial public release


13) Thanks to:
    ---------
The TI-Bank community for their encouragements.    ( http://www.ti-bank.fr )
The Omnimaga community for their encouragements and tests.  ( http://www.omnimaga.org )
ExtendeD for Ndless 1.7/2.0.
Bsl for Ndless 1.3/1.4.


14) Contact:
    -------

Xavier Andréani
[email protected]