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Mini57
Apr. 06, 2017
Page 53 of 475
Rev.1.00
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6.2.6
Register Protection
Some of the system control registers need to be protected to avoid inadvertent write and disturb
the chip operation. These system control registers are protected after the power on reset till user
to disable register protection. For user to program these protected registers, a register protection
disable sequence needs to be followed by a special programming. The register protection disable
sequence is writing the data “59h”, “16h” “88h” to the register SYS_REGLCTL continuously. Any
different data value, different sequence or any other write to other address during these three
data writing will abort the whole sequence.
After the protection is disabled, user can check REGLCTL (
SYS_REGLCTL [0]), “1” is protection
disable, “0” is protection enable. Then user can update the target protected register value and
then write any data to
SYS_REGLCTL to enable register protection.
The protected registers are listed in Table 6.2-6.
Register
Bit
Description
SYS_IPRST0
[1] CPURST
Processor Core One-shot Reset (Write Protect)
[0] CHIPRST
Chip One-shot Reset (Write Protect)
SYS_BODCTL
[15] LVREN
Low Voltage Reset Enable Control (Write Protect)
[6] BODLPM
Brown-out Detector Low Power Mode (Write Protect)
[4] BODRSTEN
Brown-out Reset Enable Control (Write Protect)
[3:1] BODVL
Brown-out Detector Threshold Voltage Selection (Write Protect)
[0] BODEN
Brown-out Detector Enable Control (Write Protect)
SYS_PORCTL
[15:0] POROFF
Power-on Reset Enable Control (Write Protect)
INT_NMICTL
[8] NMISELEN
NMI Interrupt Enable Control (Write Protected)
CLK_PWRCTL
[11:10] HXTGAIN
HXT Gain Control (Write Protect)
[7] PDEN
System Power-down Enable Control (Write Protect)
[5] PDWKIEN
Power-down Mode Wake-up Interrupt Enable Control (Write Protect)
[4] PDWKDLY
Wake-up Delay Counter Enable Control (Write Protect)
[3] LIRCEN
LIRC Enable Control (Write Protect)
[2] HIRCEN
HIRC Enable Control (Write Protect)
[1:0] XTLEN
XTL Enable Control (Write Protect)
CLK_APBCLK
[0] WDTCKEN
Watchdog Timer Clock Enable Control (Write Protect)
CLK_CLKSEL0
[4:3] STCLKSEL
Cortex® -M0 SysTick Clock Source Selection (Write Protect)
[1:0] HCLKSEL
HCLK Clock Source Selection (Write Protect)
CLK_CLKSEL1
[1:0] WDTSEL
Watchdog Timer Clock Source Selection (Write Protect)
FMC_ISPCTL
[6] ISPFF
ISP Fail Flag (Write Protect)
[5] LDUEN
LDROM Update Enable Control (Write Protect)
[4] CFGUEN
CONFIG Update Enable Control (Write Protect)