![](http://datasheet.mmic.net.cn/120000/MC68328PV_datasheet_3559354/MC68328PV_13.png)
Signals
2-10
MC68328 USER’S MANUAL 11/6/97
MOTOROLA
SIGNAL
DESCRIPTIONS
2
PRELIMINARY
LCLK—SHIFT CLOCK
This is the clock output to which the output data to the LCD panel is synchronized. LCLK
can be programmed to be inverted.
LACD—ALTERNATE CRYSTAL DIRECTION
This output is toggled to alternate the crystal polarization on the panel and is used to protect
the crystal from DC voltages. This signal can be programmed to toggle at a period from 1 to
16 frames.
2.1.17 JTAG Testing Pins
TCK—TEST CLOCK
This pin provides a test clock input for boundary scan test logic defined by the IEEE1149.1
standard. If JTAG is not used or during normal operation, TCK should be connected to an
extrnal pullup resistor.
TMS—TEST MODE SELECT
This input controls test-mode operations for onboard test logic defined by the IEEE 1149.1
standard. If JTAG is not used, this pin should be connected to VDD or pulled up through an
external pullup resistor.
TDI—TEST DATA IN
This input is used for serial test instructions and test data for internal test logic defined by
the IEEE 1149.1 standard. If JTAG is not used, this pin should be connected to VDD or
pulled up through an external pullup resistor.
TDO—TEST DATA OUT
This output is used for serial test instructions and test data for on-chip test logic defined by
the IEEE 1149.1 standard. TDO may be left not connected or may drive the TDI pin of
another device in a JTAG boundary scan chain.
JTAGRST—JTAG RESET INPUT
This input is used for resetting the JTAG module for on-chip test logic defined by the IEEE
1149.1 standard for boundary scan. In normal operation, this pin should be connected to
RESET.
2.1.18 In-Circuit Test Pin
ICHIZ—IN-CIRCUIT HIGH IMPEDANCE
This input may be used as a means of isolating MC68328 signals during in-circuit testing.
When ICHIZ is asserted, all of the MC68328 signal pins are high impedance. When HIZ is
high, the MC68328 operates normally. HIZ may also be asserted to accomodate in-circuit-
test programming of external memory components such as FLASH memories.