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1. PORT clock gate, pin mux and peripheral registers are not reset to default values on
ROM exit
Description
• Affected PORT clock gates: PORTA, PORTB, PORTC, PORTD and PORTE
(SIM_SCGC5_PORTA, SIM_SCGC5_PORTB, SIM_SCGC5_PORTC,
SIM_SCGC5_PORTD and SIM_SCGC5_PORTE are enabled)
• Affected pin mux: LPUART0(PTA1, PTA2), I2C0(PTB0,PTB1),
SPI0(PTC4,PTC5,PTC6,PTC7)
• Affected peripheral registers:
• UART and UART clock source (SIM_SOPT2_UART0SRC = 3)
• SPI
• I2C
Workaround
• User must re-configure corresponding register to expected value instead of
relying on the default value.
2. UART cannot work at 57600 baudrate with default core clock
Workaround
• Send ping packet bytes continuously without delay
• Limit highest UART clock frequency to 38400 at default clock (8 MHz)
• To improve UART throughput, configure the core clock to higher frequency
3. COP is disabled in ROM and it cannot be re-enabled by an application that is
jumped-to from ROM
Description
• SIM_COPC register is write once when out of reset, it is disabled in ROM
• User application cannot re-enable it if application is run by jumping from ROM
Workaround
• Set FOPT[BOOTSRC_SEL] = 00b, FOPT[BOOTPIN_OPT]= 0b
• With above settings, boot source of chip is selected by assertion of NMI pin; if
NMI pin is not asserted during POR reset / Chip reset, chip will boot from flash
and COP can be enabled.
Bootloader errata
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
222
Freescale Semiconductor, Inc.