% LSM330DLC Gyro connected to a Raspberry PI

Two LSM330DLC gyroscopes are connected to the Raspberry PI GPIO connector, with address decoding done my a 74AC11138 3-to-8 decoder.

The connectors are wired as follows:

	         1 O O
	           : :
	           : :
	3v3 Power  O O n/c (GPIO24)
	SPI MOSI   O O n/c (Ground)
	SPI MISO   O O GPIO 25
	SPI SCLK   O O SPI \CE0
	Ground     O O SPI \CE1

The "main" SPI signals are connected directly to the LSM330DLC. The chip-select signals are connected through a 74AC11138 with the following pins connected :

Raspberry Pin 74AC11138    LSM330DLC
------------- ------------ -----------
\CE1          Pin 13, "C"  -
\CE0          Pin 14, "B"  -
GPIO 25       Pin 15, "A"  -
-             Pin 2, "Y2"  ...?...
-             Pin 3, "Y3"  ...?...
-             Pin 5, "Y4"  ...?...
-             Pin 6, "Y5"  ...?...

Enable-pins are set to always enable the low-active decoder outputs. Truth table for the 74AC11138:

A    B    C      Active-low output of
GPIO \CE0 \CE1   decoder:
---- ---- ------ --------------------
1    1    1      \Y7 (SPI idle, not connected...)
0    1    0      \Y2
1    1    0      \Y3
0    0    1      \Y4 
1    0    1      \Y5