AK8975 Datasheet, PDF (17/34 Pages) Asahi Kasei Microsystems – 3-axis Electronic Compass

[AK8975/C]
7.1.2. Reading Data
Input the R/W control bit (R/W=“1”) and 7 bit register address on SI pin in synchronous with the first 8 bits of
the 16 bits of a serial clock input on SK pin. Then AK8975/C outputs the data held in the specified register
with MSB first from SO pin.
When clocks are input continuously after one byte of data is read, the address is incremented and data in the
next address is output. Accordingly, after the falling edge of the 15th clock and CSB pin is “L”, the data in the
next address is output on SO pin. When CSB pin is driven “L” to “H”, SO pin is placed in the high-impedance
state.
AK8975/C has two incrementation lines; 00H to 0CH and 10H to 12H. For example, data is read as follows:
00H -> 01H ... -> 0BH -> 0CH -> 00H -> 01H ..., and 10H -> 11H -> 12H -> 10H …
When specified address is other than 00H to 12H, AK8975/C recognizes that it is not selected and keeps SO
pin in high-impedance state. Therefore, user can use other addresses for other devices.
CSB
SK
1
2
3 4
5
6
7 8 9 10 11 12 13 14 15
16

SI
(INPUT)
RW A6 A5 A4
A3
A2
A1 A0
SO
(OUTPUT)
Hi-Z
Hi-Z
D7 D6 D5 D4 D3 D2 D1
D0



Figure 7.2 4-wire SPI Reading Data
MS1187-E-02
- 17 -
2010/05