MC68HC11A0CFN2(1996) Ver la hoja de datos (PDF) - Motorola => Freescale
Número de pieza
componentes Descripción
Fabricante
MC68HC11A0CFN2 Datasheet PDF : 158 Pages
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2
PB7/A15
PB6/A14
PB5/A13
PB4/A12
PB3/A11
PB2/A10
PB1/A9
PB0/A8
PC7/A7/D7
PC6/A6/D6
PC5/A5/D5
PC4/A4/D4
PC3/A3/D3
PC2/A2/D2
PC1/A1/D1
PC0/A0/D0
AS
R/W
E
MC68HC11A8
A15
A14
A13
A12
A11
A10
A9
A8
HC373
D1 Q1
A7
D2 Q2
A6
D3 Q3
A5
D4 Q4
A4
D5 Q5
A3
D6 Q6
A2
D7 Q7
A1
D8 Q8
A0
LE OE
WE
D7
D6
D5
D4
D3
D2
D1
D0
Figure 2-4 Address/Data Demultiplexing
ADDR/DATA DEMUX
2.2.3 Special Bootstrap Operating Mode
The bootstrap mode is considered a special operating mode as distinguished from the
normal single-chip operating mode. This is a very versatile operating mode since there
are essentially no limitations on the special purpose program that can be loaded into
the internal RAM. The boot loader program is contained in the 192 byte bootstrap
ROM. This ROM is enabled only if the MCU is reset in special bootstrap operating
mode, and appears as internal memory space at locations $BF40-$BFFF. The boot
loader program will use the SCI to read a 256 byte program into on-chip RAM at loca-
tions $0000-$00FF. After the character for address $00FF is received, control is auto-
matically passed to that program at location $0000.
The MC68HC11A8 communicates through the SCI port. After reset in special boot-
strap operating mode, the SCI is running at E clock/16 (7812 baud for E clock equal 2
MHz). If the security feature was specified and the security bit is set, $FF is output by
the SCI transmitter. The EEPROM is then erased. If erasure is unsuccessful, $FF is
output again and erasure is attempted again. Upon successful erasure of the EE-
PROM, all internal RAM is written over with $FF. The CONFIG register is then erased.
The boot loader program now proceeds as though the part had not been in security
mode.
MOTOROLA
2-8
SIGNAL DESCRIPTIONS AND OPERATING MODES
MC68HC11A8
TECHNICAL DATA
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