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View the latest post Classpad II fx-CP400 hardware - a hidden SD card reader ?


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:
Image

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.
Image



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! :(
Image

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! :o

Image

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! :D
Unlike older Casio Classpad models, it is possible to add a SD card memory reader to the ClassPad II! Image




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

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