Nintendo GBA tiltsensor doc:
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The tiltsensor is found in 2 different games,
Yoshi's Universal Gravitation / Yoshi Topsy Turvy and
Wario Ware Twisted.
This info is only confirmed for the Yoshi game.


Its registers are at the top "half" of the SRAM memory range,
all of them are byte accessed.

0x0E008000 (W)		Write 0x55 to start sampling?
0x0E008100 (W)		Write 0xAA to start sampling?
0x0E008200 (R)		Low 8 bits of X axis.
0x0E008300 (R)		High 4 bits of X axis plus ready (bit 7)
0x0E008400 (R)		Low 8 bits of Y axis.
0x0E008500 (R)		High 4 bits of Y axis.

You must set SRAM wait control to 8 clocks to access it correctly.
You must also set the cartridge PHI terminal to 4MHz to make it work.
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Description:
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First set SRAM wait control to 8 clocks and phi terminal output to 4MHz.
REG_WAITCNT = 0x0803;

or if you want faster rom speed, something like this:

REG_WAITCNT = 0x4817;



Somewhere in the VBlank routine, do this:

Read high x component and ready bit from 0x0E008300.
Make sure the ready bit is set, otherwise spinnwait a couple of hundered
times checking the value.
Mask out the lower 4 bits.

Read low x component from 0x0E008200.
Merge with the 4 bits from 0x0E008300.
X is ready.


Read high y component from 0x0E008500.
Mask out lower 4 bits.

Read low y component from 0x0E008400
Merge with the 4 bits from 0x0E008500.
Y is ready.


Write 0x55 to 0x0E008000
Write 0xAA to 0x0E008100

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On my cartridge I got the following readings:
Readings for X between 0x2AF to 0x477, center at 0x392.
Readings for Y between 0x2C3 to 0x480, center at 0x3A0.


/FluBBa