
CHAPTER 2 PIN FUNCTIONS
Preliminary User’s Manual U16541EJ1V0UM
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(b) Control mode
(i) A16 to A21 (address bus) … Output
These are 6-bit address output pins used by the address bus during external access. The output
changes in synchronization with the rising edge of the clock during the T1 state of the bus cycle.
When the bus cycle becomes inactive, these pins hold the address of the immediately preceding bus
cycle.
(11) PDL0 to PDL15 (port DL) … 3-state I/O
PDL0 to PDL15 function as a 16-bit I/O port for which input and output can be set in 1-bit units.
In addition to I/O pins, these pins can also be used as a time division address/data bus (AD0 to AD15) during
external memory expansion.
Moreover, during flash memory programming (input of high level to FLMD0), PDL5/AD5 function as the
FLMD1 pin. At this time, be sure to input a low level to the FLMD1 pin.
(a) Port mode
PDL0 to PDL15 can be set to input or output in 1-bit units using port mode register DL (PMDL).
(b) Control mode
(i) AD0 to AD15 (address/data bus) … 3-state I/O
These form an address/data multiplexed bus during external access. In the multiplexed bus mode,
they function as address output or data I/O, and in the separate bus mode, they function as data I/O.
(12) RESET (reset) … Input
RESET is a signal that is input asynchronously and has a low level width regardless of the status of the
operating clock. When this signal is input, a system reset is executed with a higher priority than all other
operations.
In addition to being used for ordinary initializations/start operations, this signal can also be used to release a
standby mode (HALT, IDLE1, IDLE2, software STOP).
(13) X1, X2 (crystal for main clock)
These pins are used to connect the resonator that generates the system clock.
(14) XT1, XT2 (crystal for subclock)
These pins are used to connect the resonator that generates the subclock.
(15) AVSS (ground for analog)
This is the ground pin for the A/D converter, D/A converter, and alternate-function ports.
(16) AVREF0 (analog reference voltage) … Input
This pin the analog positive power supply pin for the A/D converter and alternate-function ports.
It is also used to supply a reference voltage to the A/D converter.
(17) AVREF1 (analog reference voltage) … Input
This pin the analog positive power supply pin for the D/A converter and alternate-function ports.
It is also used to supply a reference voltage to the D/A converter.