Software Watchdog Timer (SWT)
18-2
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
continues to run. In stop mode, operation of the counter is controlled by the STP bit in the SWT_MCR. If
the STP bit is set, the counter is stopped in stop mode, otherwise it continues to run.
18.2
External Signal Description
The SWT module does not have any external interface signals.
18.3
Memory Map and Register Definition
The SWT programming model has seven 32-bit registers. The programming model can only be accessed
using 32-bit (word) accesses. References using a different size are invalid. Other types of invalid accesses
include: writes to read only registers, incorrect values written to the service register when enabled,
accesses to reserved addresses and accesses by masters without permission. If the RIA bit in the
SWT_MCR is set then the SWT generates a system reset on an invalid access otherwise a bus error is
generated. If either the HLK or SLK bits in the SWT_MCR are set then the SWT_MCR, SWT_TO,
SWT_WN, SWT_SK registers are read only.
18.3.1
Memory Map
The SWT memory map are shown in
. The base address for each SWT is given in
18.3.2
Register Descriptions
The following sections detail the individual registers within the SWT programming model.
18.3.2.1
SWT Control Register (SWT_MCR)
The SWT_MCR contains fields for configuring and controlling the SWT. This register is read only if either
the SWT_MCR[HLK] or SWT_MCR[SLK] bits are set.
Table 18-1. SWT Memory Map
Address
Offset
Register
Bits
Access
Reset Value
Section/Page
0x0000
SWT_MCR—SWT Module Control Register
32
R/W
0xFF00_0*0B
0x0004
SWT_IR—SWT Interrupt Register
32
R/W
0x0000_0000
0x0008
SWT_TO—SWT Time-out Register
32
R/W
0x0005_FCD0
0x000C
SWT_WN—SWT Window Register
32
R/W
0x0000_0000
0x0010
SWT_SR—SWT Service Register
32
R/W
0x0000_0000
0x0014
SWT_CO—SWT Counter Output Register
32
R
0x0000_0000
0x0018
SWT_SK—SWT Service Key Register
32
R/W
1
NOTES:
1
If neither HLK or SLK lock bit in the SWT_MCR is set, the SWT_SK can be initialized by software to a non-zero value.
0x0000_0000
0x001C–0x3FFF
Reserved
Summary of Contents for PXR4030
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