C M L 1 2 S D P 2 5 6
0 1 / 3 0 / 0 4
14
AUTO OFF / spare
The AUTO OFF (Spare on REV C. board) option jumper installed defeats the Autostart
operation so the MON12 monitor will provide a command prompt. The jumper applies a
ground potential to the XIRQ* interrupt line. User should only install the jumper to restore
monitor operation, perform the MON12 NOAUTO command to disable the Autostart, and
remove or idle the jumper. MON12 operation will then be provided on subsequent Reset
conditions.
MODE
The MODE option jumper is not installed on the CML12S-DP256 board and is hard connected
by circuit copper trace for Single-chip Mode operation of the CPU. Both the MODA and MODB
signals are terminated by this option. Due to the restriction that the HCS12 internal flash
memory is the only nonvolatile program memory provided on the board, single Chip Mode is
default. All other Modes can be enabled under software control from this mode of operation.
The MODE option jumper may be installed by the user by cutting the hard trace and applying 2
header pins with a shunt jumper. With the shunt jumper removed, the Reset mode will then be
Normal Expanded Wide. (Note: mask set 1K79X and earlier will not fetch the Reset vector
from external memory in this mode).
OSC_SEL
The OSC_SEL option jumper is not installed on the CML12S-DP256 board. The default
configuration is for the provided 4MHz reference crystal to provide the HCS12 oscillator. If the
user requires an external clock to be applied, two header pins and shunt jumper can be
applied to select the alternate clock source. User should refer to the HCS12 User Guide and
CML12S board schematic for proper application of the external clock.
ROM_OFF
The ROM_OFF option jumper is not installed on the CML12S-DP256 board. The default
configuration is that the internal flash memory of the HCS12 is enabled at Reset. The user
must add external nonvolatile memory to the CML12S board to take advantage of this option.
If the external memory is applied, the user may install the two header pins and shunt jumper to
select internal or external memory use form Reset.
JP1 and JP2
JP1 and 2 option jumpers provide an easy method of connecting or isolating the HCS12 SCI0
and SCI1 serial channel RXD pins respectfully from the provided on-board RS232 transceiver.
To apply the RXD pins on the SCI channels for other user applications requires that the
transceiver driver be removed from the HCS12 pin. User may then apply signals to the
respective pins at the MCU PORT connector without driver conflict. Please note that the on-
board monitor(s) require HCS12 SCI channel 0 (JP1 installed) for user interface.
