NEC uPD72257, Preliminary User'S Manual

Page: 82 / 343

2.6 Pin States with Respect to Reset
Any reset (external RESET, internal S/W reset SWRESET, Watchdog reset
WDRESET) re-initializes the pin functions to those chosen by the boot mode
function pin option MODE[3:0].
Note that groups of internal pull-up resistors are activated, depending on the
pinout option MODE[3:0].
During and after reset the pins behave as follows:
• During reset all
-
input pins are not active
- all other pins are in Hi-Z state
• For a period of four oscillator clocks CLKIN, with its frequency of the
external resonator at XT1/XT2, after reset release
-
all input pins are active
- all other pins remain in Hi-Z or are internally fixed to high level,
if the pin is equipped with an activated internal pull-up resistor
• After four oscillator clocks CLKIN after reset release all pins adopt
their final state, as specified by the boot option MODE[3:0].
Chapter 2 Pin Functions
82
Preliminary User's Manual S19203EE1V3UM00