F271-AEA-P View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
F271-AEA-P Datasheet PDF : 180 Pages
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Pin data
ST10F271B/ST10F271E
Table 1. Pin description (continued)
Symbol
Pin Type
Function
EA / VSTBY
99
External access enable pin.
A low level applied to this pin during and after Reset forces the ST10F271 to start
the program from the external memory space. A high level forces ST10F271 to
start in the internal memory space. This pin is also used (when Stand-by mode is
entered, that is ST10F271 under reset and main VDD turned off) to bias the 32
kHz oscillator amplifier circuit and to provide a reference voltage for the low-
I power embedded voltage regulator which generates the internal 1.8V supply for
the RTC module (when not disabled) and to retain data inside the Stand-by
portion of the XRAM (16Kbyte).
It can range from 4.5 to 5.5V (6V for a reduced amount of time during the device
life, 4.0V when RTC and 32 kHz on-chip oscillator amplifier are turned off). In
running mode, this pin can be tied low during reset without affecting 32 kHz
oscillator, RTC and XRAM activities, since the presence of a stable VDD
guarantees the proper biasing of all those modules.
Two 8-bit bidirectional I/O ports P0L and P0H, bit-wise programmable for input or
output via direction bit. Programming an I/O pin as input forces the corresponding
output driver to high impedance state. The input threshold of Port 0 is selectable
(TTL or CMOS).
In case of an external bus configuration, PORT0 serves as the address (A) and
as the address / data (AD) bus in multiplexed bus modes and as the data (D) bus
in demultiplexed bus modes.
Demultiplexed bus modes
P0L.0 -P0L.7,
P0H.0
P0H.1 -
P0H.7
100-107,
108,
111-117
I/O
Data path width
P0L.0 – P0L.7:
8-bit
D0 – D7
P0H.0 – P0H.7: I/O
16-bi
D0 - D7
D8 - D15
Multiplexed bus modes
Data path width
P0L.0 – P0L.7:
P0H.0 – P0H.7:
8-bit
AD0 – AD7
A8 – A15
16-bi
AD0 - AD7
AD8 - AD15
18/180
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