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Cubieboard2 NAND to Cubieboard2 DualCard

Started by MM4, March 21, 2018, 05:40:23 am

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March 21, 2018, 05:40:23 am Last Edit: April 05, 2018, 09:28:59 am by MM4

Since NAND is a pain in the back, did anybody manage to turn a Cubieboard2 NAND into a Cubieboard2 DualCard?

Taking the Chip off and soldering a second micro sd card slot is easy, but i guess you have to populate a few SMD resistors as well. Due to lack of a component placement diagram that matches the schematics, this is a bit tricky though.

So does anybody (Hello @allwinner :-)) have a component placement diagram, or alternatively a High-Res picture of the Cubieboard2 DualCard backside / second Micro-SD card connector, where one can see the surrounding resistors to give a hint which bits might need to be added?

My guess is the pull-ups and connecting resistors that are shown in the schematic are not on the NAND board by default.

Edit from 28th March 2018:

Ok continuing with the guesswork. I try to match the cubieboard_schematic_2012-08-08.pdf with the component placement document from Cubieboard1. All component indices are different though.

My current cunning guesswork:

Between component Placement Diagram cubieboard_smt_bottom-0829.pdf and cubieboard_schematic_2012-08-08.pdf the magic mapping might be:

33R Data connection to SOC:
8R1 - R20 - D1
8R2 - R22 - D0
8R4 - R23 - CLK
8R6 - R24 - CMD
8R8 - R26 - D3
8R11 - R28 - D2

47K Pullups to 3.3V
8R22 - R38 - ND1
8R21 - R37 - ND0
8R19 - R35 - NRB0#
8R24 - R40 - ND3
8R23 - R39 - ND2

I think the card detect pullup is on the other side

Between component Placement Diagram cubieboard_smt_top-0829.pdf and cubieboard_schematic_2012-08-08.pdf the magic mapping might be:
8R20 - R36 - SD2-DET#

Edit from 5th April 2018:
I got it working. In addition to the changes above, i needed to take two resistors off (remove) R41 and R42 in the schematic - aka R2 and R3 in the component placement diagram, which were 10k pull-ups for the Nand, which are connected in parallel to the 47k pull-ups for the card slot.
And i also put the 0.22µF capacitor on to debounce the card-detect pin. That was C105 in the schematic and is named 8C2 in the component placement diagram.

After changing the devicetree of linux-master the 2nd SD Card is seen and seems to work. Card-Detect also works. So i guess i can call this a success and answer my own question:
Yes you can convert a Cubieboard2 Nand to a Cubieboard2 DualCard.

Mind you without a SMD rework station with a microscope doing the mod is a bit fiddly. I was lucky enough and could use some equipment at work.

Kind Regards,