MC9S12NE64V1 Datasheet, PDF (401/554 Pages) Freescale Semiconductor, Inc – MC9S12NE64V1 Data Sheet

Memory Map and Register Definition
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Port A bits 7 through 0 are associated with address lines A15 through A8 respectively and data lines
D15/D7 through D8/D0 respectively. When this port is not used for external addresses such as in
single-chip mode, these pins can be used as general-purpose I/O. Data direction register A (DDRA)
determines the primary direction of each pin. DDRA also determines the source of data for a read of
PORTA.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
NOTE
To ensure that you read the value present on the PORTA pins, always wait
at least one cycle after writing to the DDRA register before reading from the
PORTA register.
15.3.2.2 Port B Data Register (PORTB)
7
6
5
4
3
2
R
Bit 7
6
5
4
3
2
W
Reset
0
0
0
0
0
0
Single Chip PB7
PB6
PB5
PB4
PB3
PB2
Expanded Wide,
Emulation Narrow with AB/DB7
IVIS, and Peripheral
AB/DB6
AB/DB5
AB/DB4
AB/DB3
AB/DB2
Expanded Narrow AB7
AB6
AB5
AB4
AB3
AB2
Figure 15-3. Port A Data Register (PORTB)
1
1
0
PB1
AB/DB1
AB1
0
Bit 0
0
PB0
AB/DB0
AB0
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Port B bits 7 through 0 are associated with address lines A7 through A0 respectively and data lines D7
through D0 respectively. When this port is not used for external addresses, such as in single-chip mode,
these pins can be used as general-purpose I/O. Data direction register B (DDRB) determines the primary
direction of each pin. DDRB also determines the source of data for a read of PORTB.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
NOTE
To ensure that you read the value present on the PORTB pins, always wait
at least one cycle after writing to the DDRB register before reading from the
PORTB register.
MC9S12NE64 Data Sheet, Rev. 1.1
Freescale Semiconductor
401