33884 Datasheet, PDF (15/21 Pages) Freescale Semiconductor, Inc – Switch Monitor Interface

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
TRI-STATE COMMAND
This command places an external switch into a Tri-State
condition, essentially disconnecting the wetting current (if the
switch is metallic) and the sustain current. The internal input-
threshold comparator is still internally connected to its
external pin. This command does not change the mode of
operation
CP[4:1] – CONFIGURE PROGRAMMABLE SWITCH
Configure the programmable inputs SP[4:1] to detect
either an external switch-to-ground (internal current source)
or an external switch-to-battery (internal current sink).
Note: This configuration may be entered in any of the three
valid Operating Modes (see MOD[2:1]) within the Run
command.
Table 11. Programmable Switch Bit Definition
CPx
External Switch to:
0
Ground
1
Battery
(e.g., a Tri-State command received while in the Polling
mode leaves the part in that mode).
Note: The Tri-State register clears all bits to logic [0] (all
inputs in Tri-State) in response to a hardware reset; all inputs
also remain in Tri-State after existing the Sleep mode.
Table 12. Tri-State Command
Command
MSB
LSB
16 15 14 13 12
11
10
9
8
7
6
5
4
3
2
1
Tri-State
0 0 1 1 TG6 TG5 TG4 TG3 TG2 TG1 TP4 TP3 TP2 TP1 TB2 TB1
Reset Values:
Run Register
———— 0
0
0
0
0
0
0
0
0
0
0
0
TG[6:1] = Tri-state switch-to-ground
TB[2:1] = Tri-state switch-to-battery
TP[4:1] = Tri-state programmable switch
Table 13. Programmable Switch Bit Definition
TGx, TBx, TPx
Input Configured to:
0
Input Disabled (Default)
1
Input Enabled
METALLIC COMMAND
This command enables the pulsed wetting current for an
external metallic switch and disables it for an external non-
metallic switch. This command does not change the mode of
operation (e.g., a Metallic command received while in Polling
mode leaves the part in that mode). Note that the Run
register values are unknown after exiting the Sleep mode.
Table 14. Metallic Command
MSB
Command
16 15 14 13 12 11 10
9
8
7
Metallic
0 1 0 1 MG6 MG5 MG4 MG3 MG2 MG1
Reset Values:
Run Register
———— U
U
U
U
U
U
U = Unknown value coming out of Sleep mode. It must be configured with Run command.
MG[6:1] = Metallic switch-to-ground
MB[2:1] = Metallic switch-to-battery
MP[4:1] = Metallic programmable switch
6
MP4
U
5
MP3
U
4
MP2
U
3
MP1
U
2
MB2
U
LSB
1
MB1
U
Table 15. Metallic Switch Bit Definition
MGx, MBx, MPx
Accept Switch Type:
0
Non-Metallic
1
Metallic (Enable Wetting Current Pulse)
Analog Integrated Circuit Device Data
Freescale Semiconductor
33884
15