Monitor ROM (MON)
Functional Description
MC68HC908AZ60A — Rev 2.0 Technical Data
MOTOROLA Monitor ROM (MON) 219
14.4.7 MC68HC908AZ60A Baud Rate
The MC68HC908AZ60A features a monitor mode which is optimised to
operate with either a 4.9152 MHz crystal clock source (or multiples of
4.9152 MHz) or a 4 MHz crystal (or multiples of 4 MHz). This supports
designs which use the MSCAN module, which is generally clocked from
a 4 MHz, 8 MHz or 16 MHZ internal reference clock. The table below
outlines the available baud rates for a range of crystals and how they can
match to a PC baud rate.
Care should be taken when setting the baud rate since incorrect
baud rate setting can result in communications failure.
Table 14-10 MC68HC908AZ60A Monitor Baud Rate Selection
Baud rate Closest PC baud PC Error %
Clock freq PTC3=0 PTC3=1 PTC3=0 PTC3=1 PTC3=0 PTC3=1
32kHz 57.97 28.98 57.6 28.8 0.64 0.63
1MHz 1811.59 905.80 1800 900 0.64 0.64
2MHz 3623.19 1811.59 3600 1800 0.64 0.64
4MHz 7246.37 3623.19 7200 3600 0.64 0.64
4.194MHz 7597.83 3798.91 7680 3840 1.08 1.08
4.9152MHz 8904.35 4452.17 8861 4430 0.49 0.50
8MHz 14492.72 7246.37 14400 7200 0.64 0.64
16MHz 28985.51 14492.75 28800 14400 0.64 0.64
