PXN20RM Datasheet, PDF (480/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Software Watchdog Timer (SWT)
20.3 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_CR
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_CR are set, then the SWT_CR, SWT_TO, SWT_WN, and
SWT_SK registers are read-only.
20.3.1 Memory Map
The SWT memory map is shown in Table 20-1.
Table 20-1. SWT Memory Map
Offset from
SWT_BASE
(0xFFF3_8000)
Register
0x0000
SWT_CR – SWT control register
0x0004
SWT_IR – SWT interrupt register
0x0008
SWT_TO – SWT time-out register
0x000C
SWT_WN – SWT window register
0x0010
SWT_SR – SWT service register
0x0014
SWT_CO – SWT counter output register
0x0018
SWT_SK – SWT service key register
0x001C– 0x3FFF Reserved
Access Reset Value Section/Page
R/W 0xFF00_0103 20.3.2.1/20-2
R/W 0x0000_0000 20.3.2.2/20-4
R/W 0x0002_7100 20.3.2.3/20-4
R/W 0x0000_0000 20.3.2.4/20-5
R/W 0x0000_0000 20.3.2.5/20-6
R
0x0000_0000 20.3.2.6/20-6
R/W 0x0000_0000 20.3.2.7/20-7
20.3.2 Register Descriptions
The following sections detail the individual registers within the SWT.
20.3.2.1 SWT Control Register (SWT_CR)
The SWT_CR contains fields for configuring and controlling the SWT. This register is read-only if either
the SWT_CR[HLK] or SWT_CR[SLK] bits are set.
20-2
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor