DS80C390_00 Datasheet, PDF (23/155 Pages) Dallas Semiconductor – High-Speed Microcontroller User’s Guide Supplement

DS80C390 High-Speed Microcontroller User’s Guide Supplement
Port 4 Control Register (P4CNT)
7
6
5
4
3
2
1
0
SFR 92h
1
SBCAN P4CNT.5 P4CNT.4 P4CNT.3 P4CNT.2 P4CNT.1 P4CNT.0
R-1
RT-0
RT-1
RT-1
RT-1
RT-1
RT-1
RT-1
R=Unrestricted Read, T=Timed Access Write Only, -n=Value after Reset
P4.7-0
Bit 7
SBCAN
Bit 6
P4CNT.5-
P4CNT.3
P4CNT.2-
P4CNT.0
Port 4 Control Register. This register controls the alternate addressing modes
function of Port 4. Programming this register as shown below will assign the
alternate functions of Port 4. The associated Port 4 SFR bit must be programmed to
a logic one before the pin can be used in its alternate function capacity.
Reserved
Single Bus CAN. Setting this bit connects both CAN receive inputs (C0RX and
C1RX) to P5.1 and drives P5.0 with the logical AND of both CAN transmit outputs
(C0TX and C1TX). SBCAN=0 disables the feature and allows the CAN modules to
receive/transmit through their respective bus pins. This can be used to create a
single "super" CAN module with 30 message centers.
Port Pin P4.7-P4.4 Configuration Control Bits
Various settings of bits 5-0 will configure the Chip Enable and A19-A16 address
signals of Port 4. CE0 − CE3 can be individually configured as program or data
memory, via the MCON SFR. When CE0 − CE3 are converted from program to
data memory, the respective PCE0 − PCE3 will be disabled. The number of
external address lines (A19-A16) enabled by the P4CNT.5 - P4CNT.3 control bits
establishes the internally decoded range for each program chip enable
( PCE0 − PCE3 ). When the external address bus is limited to A15-A0, the chip
enables are internally decoded on a 32KB block boundary.
P4CNT.5-3
000
100
101
110
111
Port 4 Pin Function
P4.7
P4.6
P4.5
P4.4
I/O
I/O
I/O
I/O
I/O
I/O
I/O
A16
I/O
I/O
A17
A16
I/O
A18
A17
A16
A19
A18
A17
A16
Max. Memory
Size per CEx
32 kbytes
128 kbytes
256 kbytes
512 kbytes
1 Mbytes
Port Pin P4.3-P4.0 Configuration Control Bits
Port 4 Pin Function
P4CNT.2-0
P4.3
P4.2
P4.1
P4.0
000
I/O
I/O
I/O
I/O
100
I/O
I/O
I/O
CE0
101
I/O
I/O
CE1
CE0
110
I/O
CE2
CE1
CE0
111
CE3
CE2
CE1
CE0
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