st10f269z1 STMicroelectronics, st10f269z1 Datasheet - Page 132

• Manufacturer Part Number: st10f269z1
• Description: St10f269 16-bit Mcu With Mac Unit, 256k Byte Flash Memory And 12k Byte Ram
• Manufacturer: STMicroelectronics

20 - SPECIAL FUNCTION REGISTER OVERVIEW
20.2 - System Configuration Registers
The ST10F269 has registers used for different configuration of the overall system. These registers are
described below.
SYSCON (FF12h / 89h)
Notes: 1. These bit are set directly or indirectly according to PORT0 and EA pin configuration during reset sequence.
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15 14 13
XPER-SHARE
VISIBLE
XPEN
BDRSTEN
OWDDIS
PWDCFG
CSCFG
WRCFG
STKSZ
RW
2. Register SYSCON cannot be changed after execution of the EINIT instruction.
ROMS1 SGTDIS ROMEN BYTDIS CLKEN WRCFG CSCFG
RW
12
XBUS Peripheral Share Mode Control
‘0’: External accesses to XBUS peripherals are disabled
‘1’: XBUS peripherals are accessible via the external bus during hold mode
Visible Mode Control
‘0’: Accesses to XBUS peripherals are done internally
‘1’: XBUS peripheral accesses are made visible on the external pins
XBUS Peripheral Enable bit
‘0’: Accesses to the on-chip X-Peripherals and XRAM are disabled
‘1’: The on-chip X-Peripherals are enabled.
Bidirectional Reset Enable
‘0’: RSTIN pin is an input pin only. (SW Reset or WDT Reset have no effect on this pin)
‘1’: RSTIN pin is a bidirectional pin. This pin is pulled low during 1024 TCL during reset sequence.
Oscillator Watchdog Disable Control
‘0’: Oscillator Watchdog (OWD) is enabled. If PLL is bypassed, the OWD monitors XTAL1 activity. If
there is no activity on XTAL1 for at least 1 s, the CPU clock is switched automatically to PLL’s
base frequency (from 2 to 10MHz).
‘1’: OWD is disabled. If the PLL is bypassed, the CPU clock is always driven by XTAL1 signal. The
PLL is turned off to reduce power supply current.
Power Down Mode Configuration Control
‘0’: Power Down Mode can only be entered during PWRDN instruction execution if NMI pin is low,
otherwise the instruction has no effect. Exit power down only with reset.
‘1’: Power Down Mode can only be entered during PWRDN instruction execution if all enabled fast
external interrupt EXxIN pins are in their inactive level. Exiting this mode can be done by asserting
one enabled EXxIN pin or with external reset.
Chip Select Configuration Control
‘0’: Latched Chip Select lines: CSx change 1 TCL after rising edge of ALE
‘1’: Unlatched Chip Select lines: CSx change with rising edge of ALE.
Write Configuration Control (Inverted copy of bit WRC of RP0H)
RW
11
RW
10
1
RW
9
1
RW
8
SFR
RW
7
1
RW
6
PWD
CFG
RW
5
OWD
RW
DIS
4
STEN
BDR
RW
3
XPEN VISIBLE
Reset Value: 0xx0h
RW
2
RW
ST10F269
1
SHARE
XPER-
RW
0