M 6 8 E V B 9 1 2 C 3 2
0 5 / 1 5 / 0 3
10
MODC Option
MODC jumper option selects Special or Development Mode of operation when in the GND or
logic low position. The MODC option jumper must be configured correctly for proper operation
of the EVB board and 9S12C32. The option jumper should be in the default Normal mode
position at all times unless a BDM cable is attached to the BDM PORT. When a BDM cable is
attached to the BDM_PORT the MODC option must be placed in the Special Mode or GND
position.
MODC
GND (Logic low, Special Modes and BDM cable is attached)
+5V (Logic high,
Default =
Normal Modes
)
ROM_EN Option
ROM_EN option is a hardwired by circuit trace option that enables the MC9S12C32 internal
flash in all modes. The EVB board does not provide expanded mode operation support circuits
so this option should not need modified by the user.
TEST Option
The TEST option is provided for factory use and should not be modified by the user.
Oscillator X1 and Y1
The EVB provides versatile oscillator application with the Y1 crystal circuit or the X1 clock
oscillator location. Option jumpers OSC_SEL and OSC_SEL2 select the oscillator source and
type for the HCS12 device. The option jumpers allow both types of oscillator source to be
installed on the EVB board without conflicts.
Default oscillator on the EVB is an 8Mhz clock oscillator installed in the X1 socket. The X1
socket provides for installation of standard half or full size CAN type clock oscillators that
operate at 5VDC. A buffer circuit (U3) provided on the EVB limits the X1 output to 2.5Vpp for
compatibility with the HCS12 EXTAL input.
Crystal location Y1 and associated components C1, C2, R34, and R35 (SMT 1206 size)
provide for user application of a crystal oscillator. The user should refer to the HCS12 device
user manual for information on frequency selection. The large Y1 component landing pads
accommodate several types of surface mount crystal packages however, the surface mount
HC49US type is most common. Loading capacitors C1 and C2 should be determined by the
crystal specification. R34 provides series loading and R35 provides parallel loading with the
crystal.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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