33884 Datasheet, PDF (17/21 Pages) Freescale Semiconductor, Inc – Switch Monitor Interface

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
NORMAL AND PERIODIC
Bits [16:15] identify one of the three operating modes:
Normal, Polling, and Polling + INT Timer. The remaining bits
identify the device as the Master or a Slave, whether the
device has an interrupt that has not been cleared, and the
state of all the inputs.
Table 19. Normal and Periodic
MSB
LSB
Mode
16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
Normal
0 1 MASL INT SG6 SG5 SG4 SG3 SG2 SG2 SG1 SP3 SP2 SP1 SB2 SB1
Polling
10
x
—
—
Polling + INT Timer _{1 1}
INT
—
—
Note: The SPI response given while sending the command to exit Sleep mode should be ignored due to unknown power-up state.
MASL– MASTER/SLAVE IDENTIFICATION FLAG
This flag is the same as the state of the MASL pin. It
provides software identification of the configuration of each
IC.
Table 20. MASL Bit Definition
MASL
0
Device is a:
Slave
1
Master
INT – EXTERNAL INTERRUPT FLAG
This flag identifies this particular IC as the initiator of an
external interrupt. It is the inverse of INT.
Table 21. MASL Bit Definition
MASL
16 15 14 13 Type of Interrupt
Normal
0 1 x 0 Nothing Happened
——— 1
Switch Interrupt
Polling
10xx
—
1 1 x 0 Nothing Happened
Polling + INT
Timer
— — — 1 Wake up Interrupt
SG[6:1] = Switch-to-ground flag
SB[2:1] = Switch-to-battery flag
SP[4:1] = Programmable switch flag
These twelve flags indicate the state of all switch inputs:
Table 22. Switch State Bit Definition
SGx, SBx, SPx
External
Switch is:
Mode Input States Latched:
0
Open
Normal At the moment CS
transitions to logic 0
1
Closed
Polling
TRI-STATE
All Tri-State inputs have their wetting and sustain currents
disabled. By definition, all disabled inputs return the following
value for the switch state whenever SPI data is exchanged:
Table 23. Tri-State Bit Definition
SGx, SBx, SPx
External Switch is:
0
Tri-State
Analog Integrated Circuit Device Data
Freescale Semiconductor
33884
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