System Control Registers
221
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
System Control and Interrupts
Table 1-101. Missing Clock Reference Limit (MCLKLIMIT) Register Field Descriptions
Bit
Field
Value
Description
31-16
Reserved
Reserved
15-8
REFCLKHILIMIT
Reference Clock High Limit
Contains the higher limit for the reference clock counter.
7-0
REFCLKLOLIMIT
Reference Clock Low Limit
Contains the lower limit for the reference clock counter.
NOTE:
Due to the asynchronous nature of the missing clock detect block, the MCLKDETEN = 0 write will
take 3 cycles (2 cycles best case) for the 10MHZ clock to generate the synchronized reset for the internal
counters. Hence if MCLKDETEN = 0 and REFCLKHILIMIT/REFCLKLOLIMIT values are set back to back,
then MCLKDETEN = 0, will not propagate to the counters. As a result, the new
REFCLKHILIMIT/REFCLKLOLIMIT values will take effect and may generate a missing_clock condition.
This can be avoided by adding three empty cycles between setting MCLKDETEN = 0 and setting the
REFCLKHILIMIT and REFCLKLOLIMIT values.
1.13.6.7 C28 USER_SWREG1 Register
This register is used by the PIE mismatch handler in C-Boot ROM as mentioned in the safety features
section of this chapter. The user should initialize this register with the lower 16 bits of the application PIE
mismatch handler address. If the user doesn’t wish to install a PIE mismatch handler, this register is to be
left at its reset value.
Figure 1-91. C28 USER_SWREG1 Register
15
0
SWREG1
R/W-0xFFFF
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-102. C28 USER_SWREG1 Register Field Descriptions
Bit
Field
Value
Description
15-0
SWREG1
General purpose register for C28 software use.
1.13.6.8 C28_USER_SWREG2 Register
This register is used by the PIE mismatch handler in C-Boot ROM as mentioned in the safety features
section of this chapter. The user should initialize the lower 8 bits of this register with the upper 8 bits of the
application PIE mismatch handler address (note that on the C28x addresses are limited to 22 bits). If the
user does not wish to install a PIE mismatch handler then this register is to be left at its reset value.
Figure 1-92. C28_USER_SWREG2 Register
15
14
9
8
7
0
Reserved
SWREG2
Reserved
SWREG2
R-0
R/W-0:0
R-0
R/W-
0:0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-103. C28_USER_SWREG2 Register Field Descriptions
Bit
Field
Value
Description
15
Reserved
Reserved
14-9
SWREG2
General purpose register for C28 software use.
0
1
8
Reserved
Reserved