Classpad II fx-CP400 hardware - a hidden SD card reader ?

[critor Profile]

Today let's discover the Casio ClassPad II fx-CP400 hardware together.

The calculator is quite easy to open once you get the trick. After removing all 6 screws on the back (including 4 inside the battery compartement), the entire front plate (screen and keyboard included) must be detached from the case by forcing on one of the corners




And now, you get the ClassPad II fx-CP400 hardware:


The hardware consists of two distinct PCBs :

• the power supply board RJA527047-001V01 (LY777-E4W)
• the motherboard RJA527046-001V02 (LY777-1)

It seems that is the second version of the motherboard, but of the first version of the power supply board.
We can take that with two distinct boards, a future version powered by a rechargeable battery would be quite easy, and the system already supports it.




The motherboard seems to have a setup close to the ones found on most recent Casio graphic calculators USB (Casio fx-9750Gii/fx-9860Gii, Casio Prizm fx-CG10/20).

It's built around 3 integrated chipsets:

• at position U101, a processor chip on which we can't get more information for now, as it's been drowned in a solid epoxy drop (which is usual with Casio)
• at position U231, a huge SDRAM memory chip - M12L128168A from ESMT - 2Mbits x 16-bits x 4 banks, which results in a 2 MB RAM
• at position U221, a NAND Flash memory chip - S99 50338 from Spansion - however its datasheet is not public

About the RAM, the RAM chip was also 2MB on the Casio Prizm, but only 64KB were available for the user. And here in a similar way, we've only got 512 KB available for the user!


About the NAND Flash ROM, if the informations found on the official website are accurate, the chip should have a capacity of 32MB, but only 5.5MB would remain available for the end user.



About the connectivity, a huge surprise awaits us. We've got:

• at positions HS401 et CN501, the connections to the power supply board
• at position CN401, the mini-Jack connector to transfer data between calcuators
• at position CN102, the mini-USB connector for a computer
• at position CN703, an unsoldered connector!

This CN703 connector with its pinout of 9 contacts and one lateral contact, and by its shape that gives an empty space on the board is clearly a connector for an SD memory card reader!
Unlike older Casio Classpad models, it is possible to add a SD card memory reader to the ClassPad II!




We're not sure if Casio has a future project for this since it would be a forbidden module by exam regulations of some countries (including France).
Traces of SD memory card reader support were already found on TI-Nspire and even on Casio Prizm fx-CG10/20 operating systems, although they were clearly missing from the hardware.
In fact, it seems those readers are used during hardware development where they give a way to reprogram or emulate easily the content of the ROM memory during tests - and so avoid permanently bricking the calculator prototypes with bad code: you just need to switch the SD card.

However, the community could clearly wonder if there wouldn't be some possibility for us to add a working SD card reader ourselves



Source:
http://tiplanet.org/forum/viewtopic.php?t=12716&lang=en

[gbl08ma Profile Website]

Seems to have pretty much the same hardware as the Prizm - 2 MB RAM, 32 MB NAND, and maybe even the CPU is the same but just clocked at a higher speed (the Prizm CPU can go over 400 MHz I think, it's only the peripherals that force it to run slow, otherwise it would crash). The Prizm's motherboard model is, if I remember correctly, LY755, and this one is LY777.

As for RAM "available to the user", you certainly mean "Main Memory capacity". On the Prizm, add-ins have access to over 600 KB of RAM (stack+heap, letting alone ILRAM and RS memory...).
If the Classpad III has 512 KB of Main Memory, it looks like they significantly reduced the OS memory footprint (or else they just ended with the add-in stack and put the MCS there - not impossible...)

[helder7]

Someone from cncalc in 2010 also found a hidden SD card reader in Casio fx9860g Slim and tried to make an hardware mod.
I do not know if it was successful or not, here is the link http://www.cncalc.org/thread-2376-1-1.html

Currently I do not need a SD card reader, 24 mb are enough for me.

If anyone wants to try, there are some sd card options in Diagnostics to test.