Casio fx-991EX QR code

Reverse engerneeing the Casio QR code. Here is a self made Web Demo.

Why we want to make out how QR code works?

The app or say the website Casio provided is awlful and must be online to use it. We can try to search out how the QR code works and make your own program to read data from the calculator.

Summary

The QR code can be generated when there is result (to visulize results) or in mode select page (jump to a instruction). The QR code include a web URL which contains information, we can dig out how the URL related to our result and find out how to develop our own app finally.

Basics

For example, an URL like http://wes.casio.com/math/index.php?q=I-255A+U-00030008EF6F+M-C10000AA00+S-401410101010101E1010B0000C41+R-0314159265358980010000000000000000000000+E-22 is combined with the following parts.

URL parts	description
http://wes.casio.com/math/index.php?	the domain where Casio store thier service
I-255A	UNKNOWN
U-00030008EF6F	UNKNOWN
M-C10000AA00	UNKNOWN
S-401410101010101E1010B0000C41	relative with current SETUP
R-0314159265358980010000000000000000000000	relative with calculate result
E-22	the intput formula present by number pairs

KEY-VALUE relationship

As description in Basics we can find out what input is with number pairs after E- like E-22 presents . Here is number list:

Numbers

key	value
30
31
32
33
34
35
36
37
38
39
21
22
2D
2E

Variables

key	value
42
43
44
45
46
47
48
49
40

Elementary Mathematics

key	value
A6
A7
A8
A9
741Axx1B
CA1D1Axx（degree of root)1B1Axx(radicand)1B1E
681Axx1B
C81D1Axx(numerator)1B1Axx(denominator)1B1E
181F1D1Axx(integer)1B1Axx(numerator)1B1Axx(denominator)1B1E
D7
D8
60
D0
C0
xx(base)C91Axx(power)1B
721Axx(power)1B
731Axx(power)1B
75
7D
7D1Axx(base)1Cxx(proper)1B