System bus frequency, Uart baud rate, System bus frequency -4 – Freescale Semiconductor 802.15.4 User Manual
Page 16: Uart baud rate -4, 3 system bus frequency, 4 uart baud rate
2-4 Embedded Bootloader Reference Manual, Rev 0.0 Freescale Semiconductor
2.3 System Bus Frequency
The MC908HCS08GB60/GT60 starts in 4 MHz self clocked mode. The init code changes this to 8 MHz
after a few instructions from reset.
If NVM data is found, the system clock (MC908HCS08GB60/GT60 ICG module and MC13192 CLKO)
and other options are setup as specified by the uploaded application. See the Freescale 802.15.4
MAC/PHY Software Reference Manual, 802154MPSRM/D, for more details.
If no NVM data can be found, the following (safe mode boot) values are used:
•
MC13192 CLKO = 62.5 KHz
•
MC908HCS08GB60/GT60 bus clock = 16 MHz
2.4 UART Baud Rate
If NVM data is found, the UART baud rate is setup as specified by the uploaded application. Several
values can be used. See the MC908HCS08GB60/GT60 MCU Data Sheet, MC9S08GB60/D for more
information.
The baud rate depends on the NVM values specified by the application. See the Freescale 802.15.4
MAC/PHY Software Reference Manual, 802154MPSRM/D, for more details.
If no NVM data is found, the following (safe mode boot) values are used:
•
UART baud rate 19200 kbps, 8 data, 1 start, 1 stop, none parity.