Functional Description
546
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Internal Memory
Table 7-4. MEMTIM0 Register Configuration and Frequency
CPU Frequency range
(f) in MHz
Time Period Range (t)
in ns
EEPROM Bank Clock
High Time (EBCHT)
EEPROM Bank Clock
Edge (EBCE)
EEPROM Wait States
(EWS)
16
62.5
0x0
1
0x0
16 < f
≤
40
62.5 > t
≥
25
0x2
0
0x1
40 < f
≤
60
25 > t
≥
16.67
0x3
0
0x2
60< f
≤
80
16.67 > t
≥
12.5
0x4
0
0x3
80 < f
≤
100
12.5 > t
≥
10
0x5
0
0x4
100< f
≤
120
10 > t
≥
8.33
0x6
0
0x5
NOTE:
The associated flash and EEPROM fields in the MEMTIM0 register must be programmed to
the same values. For example, the FWS field must be programmed to the same value as the
EWS field.
7.2.4.1.3 Locking and Passwords
The EEPROM can be locked at both the module level and the block level. The lock is controlled by a
password that is stored in the EEPROM Password (EEPASSn) registers and can be any 32-bit to 96-bit
value other than all 1s. Block 0 is the master block, the password for block 0 protects the control registers
as well as all other blocks. Each block can be further protected with a password for that block.
If a password is registered for block 0, then the whole module is locked at reset. As a result, the
EEBLOCK register cannot be changed from 0 until block 0 is unlocked.
A password registered with any block, including block 0, allows for protection rules that control access of
that block based on whether it is locked or unlocked. Generally, the lock can be used to prevent write
accesses when locked or can prevent read and write accesses when locked.
All password protected blocks are locked at reset. To unlock a block, the correct password value must be
written to the EEPROM Unlock (EEUNLOCK) register by writing to it once, twice, or three times,
depending on the size of the password. A block or the module can be re-locked by writing 0xFFFF.FFFF
to the EEUNLOCK register because 0xFFFF.FFFF is not a valid password.
7.2.4.1.4 Protection and Access Control
The PROT protection field in the EEPROM Protection (EEPROT) register provides discrete control of read
and write access for each block which allows various protection models per block. The protection
configurations allowed are as follows:
•
PROT = 0x0
–
Without password: Readable and writable at any time. This mode is the default when there is no
password.
–
With password: Readable, but only writable when unlocked by the password. This mode is the
default when there is a password.
•
PROT = 0x1
–
With password: Readable or writable only when unlocked.
–
This value has no meaning when there is no password.
•
PROT = 0x2
–
Without password: Readable but not writable.
–
With password: Readable only when unlocked, not writable under any conditions.
Additionally, access protection can be applied based on the processor mode. This configuration allows for
supervisor-only access or supervisor and user access, which is the default. Supervisor-only access mode
also prevents access by the µDMA and Debugger.