CMS32L051 User Manual |Chapter 24 Security Features
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24.3.4 SFR protection function
In order to ensure safety during operation, the IEC61508 standard requires that even if the CPU is
out of control, important SFRs need to be protected from overriding the SFR protection function for the
protection of port functions, interrupt functions, clock control functions, voltage detection circuitry and
RAM The parity error detection function controls the data of the register.
If the protection function is set to SFR, the write operation of the protected SFR is invalid, but it can
be read normally.
24.3.4.1 SFR protection control register (SFRGD)
This register controls whether the SFR protection function is effective.
The SFR protection function uses the G-COMP BIT, GPORT BIT, GINT BIT, and GCSC bits.
The SFRGD register is set via an 8-bit memory operation command.
After the reset signal is generated, the value of this register becomes 00H.
Figure 24-9 Format of SFR protection control register (SFRGD)
Address: 40040478H After reset: 00HR/W
Symbol
7 6 5 4 3 2 1 0
SFRGD
Protection of control registers for port functions
Invalid. Control registers that can read and write port functions.
Valid. The port function of the control register is invalid and can be read.
[SFR] PMxx protected, PUxx, PDxx, POMxx, PMCxx, PxxCFG, PIORx
Note
Interrupt function register protection
Void. Control registers that can read and write interrupts.
Effective. The write operation of the control register of the interrupt function is invalid and can
be read.
[SFR protected] IFxx , MKxx, PRxx, EGPx, EGNx
Protection of control registers for clock control functions, voltage detection circuits, and
RAM parity error detection functions
Void. Control registers that can read and write clock control functions, voltage detection
circuitry, and RAM parity error detection functions.
Effective. The write operation of the control register of the clock control function, voltage
detection circuit, and RAM parity error detection function is invalid and can be read.
[Protected SFR]CMC, CSC, OSTS, CKC, PERx, OSMC, LVIM, LVIS, RPECTL
Note Pxx (port registers) are not protected.
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