M 5 2 2 3 3 D E M O
S E P T E M B E R 2 5 , 2 0 0 6
13
Figure 6. VX_EN Option Header
ON
Enable power connection to connector J1
VX_EN
▪
▪
OFF
Disable power connection to connector J1
VX_EN
CAUTION:
Do not apply power to connector J1 while also sourcing power from either the PWR
connector or the USB-BDM circuit. Damage to the board may result.
NOTE
: Do not exceed available current supply from USB-BDM cable or on-board regulator
when sourcing power through connector J1 to external circuitry.
RESET
The MCF52233 can be reset several ways. A logic low applied to the RSTI* input will force the
device into RESET. This input is used by the RESET pushbutton. This input is also used to
force the device in to BDM mode. An internal low-voltage detect forces the part into RESET
when voltage falls too low.
RESET SWITCH
The RESET switch provides a method to apply an asynchronous reset to the MCU and is con-
nected directly to the RSTI* input on the MCU. Pressing the RESET switch forces RSTI* low
until the switch is released. An external pull-up on the RSTI* line prevents spurious resets and
allowing normal operation.
LOW VOLTAGE DETECT
The MCF52233 applies an internal Low Voltage Detect (LVD) to protect against under-voltage
conditions. The LVD is enabled out of RESET. Consult the MCF52235 Integrated Microcon-
troller Reference Manual for details on configuring LVD operation.
RESET INDICATOR
The RST_LED is connected to the RSTO* output on the MCF52233. This LED lights when the
MCU is in RESET and remains on for the duration of an asserted RSTO* signal. RSTO* may
also be used as a GP output to drive the RST_LED indicator as needed.
