6-12
MCF5272 User’s Manual
Programming Model
Figure 6-7. Device Identification Register (DIR)
Table 6-8 describes the DIR fields.
6.2.8 Software Watchdog Timer
The software watchdog timer prevents system lockup should the software become trapped
in loops with no controlled exit. The software watchdog timer can be enabled or disabled
through WRRR[EN]. If enabled, the watchdog timer requires the periodic execution of a
software watchdog servicing sequence. If this periodic servicing action does not occur, the
timer counts until it reaches the reset timeout value, resulting in a hardware reset with
RSTO driven low for 16 clocks. SCR[RSTSRC] is updated to indicate that the software
watchdog caused the reset.
If an interrupt timeout value is programmed in WIRR, and this value is reached prior to the
reset timeout value, WER[WIE] is set and a maskable interrupt is issued at the level defined
by ICR4[SWTOIPL].
The software watchdog consists of a 16-bit counter with a 10-bit prescaler. It counts up to
a maximum of 65536, with a resolution of 32768 clock periods. Thus, at 66 MHz, the
resolution of the watchdog is 0.5 msec, with a maximum timeout period of 32768 * 65536
= 2
31
clock periods or 32.54 S.
Timeout = (WRRR +1) * 32768 clocks
31
28 27
22 21
12 11
1
0
Field
Version
Number
Design Center
Device Number
JEDEC ID
—
Value
0010
forK75N
0100_01
00_0000_0011
0000_0001_110
1
R/W
Read only
Address
MBAR+0x010
Table 6-8. DIR Field Descriptions
Bits
Description
31–28 Version number. Indicates the revision number of the MCF5272.
27–22
Design center. Indicates the ColdFire design center
21–12
Device number. Indicates an MCF5272
11–1
Indicates the reduced JEDEC ID for Motorola. Joint Electron Device Engineering Council (JEDEC)
Publication 106-A and Chapter 11 of the IEEE Standard 1149.1 give more information on this field.
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...