C8051F020 查看數據表（PDF） - Silicon Laboratories
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C8051F020 Datasheet PDF : 272 Pages
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C8051F020/1/2/3
17.1.7. External Memory Interface Pin Assignments
If the External Memory Interface (EMIF) is enabled on the Low ports (Ports 0 through 3), EMIFLE (XBR2.1) should
be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and if the External Mem-
ory Interface is in Multiplexed mode, P0.5 (ALE). Figure 17.4 shows an example Crossbar Decode Table with
EMIFLE=1 and the EMIF in Multiplexed mode. Figure 17.5 shows an example Crossbar Decode Table with
EMIFLE=1 and the EMIF in Non-multiplexed mode.
If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the External
Memory Interface will control the output states of the affected Port pins during the execution phase of the MOVX
instruction, regardless of the settings of the Crossbar registers or the Port Data registers. The output configuration of
the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output
drivers on the Data Bus. See Section “16. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP
XRAM” on page 145 for more information about the External Memory Interface.
Figure 17.4. Priority Crossbar Decode Table
EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xFF)
P0
P1
P2
P3
Crossbar Register Bits
PIN I/O 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
TX0
●
RX0
●
UART0EN: XBR0.2
SCK
●●
MISO
MOSI
●●
●●
SPI0EN: XBR0.1
NSS
●
●
SDA
●●●
SCL
●●
●
●●
SMB0EN: XBR0.0
TX1
●●●
RX1
●●
●●
● ●●●
UART1EN: XBR2.2
CEX0
●
●
●
● ●●●
CEX1
●●
● ●●●●●
CEX2
●●
● ●●●●●
PCA0ME: XBR0.[5:3]
CEX3
●
● ●●●●●●●
CEX4
●
● ●●●●●●●
ECI
●●●●●
●●●●●●●●●●●
ECI0E: XBR0.6
CP0
●●●●●
●●●●●●●●●●●●
CP0E: XBR0.7
CP1
●●●●●
●●●●●●●●●●●●●
CP1E: XBR1.0
T0
●●●●●
●●●●●●●●●●●●●●
T0E: XBR1.1
/INT0 ● ● ● ● ●
●●●●●●●●●●●●●●●
INT0E: XBR1.2
T1
●●●●●
●●●●●●●●●●●●●●●●
T1E: XBR1.3
/INT1 ● ● ● ● ●
●●●●●●●●●●●●●●●●●
INT1E: XBR1.4
T2
●●●●●
●●●●●●●●●●●●●●●●●●
T2E: XBR1.5
T2EX ● ● ● ● ●
●●●●●●●●●●●●●●●●●●●
T2EXE: XBR1.6
T4
●●●●●
●●●●●●●●●●●●●●●●●●●●
T4E: XBR2.3
T4EX ● ● ● ● ●
●●●●●●●●●●●●●●●●●●●●●
T4EXE: XBR2.4
/SYSCLK ● ● ● ● ●
●●●●●●●●●●●●●●●●●●●●●●
SYSCKE: XBR1.7
CNVSTR ● ● ● ● ●
●●●●●●●●●●●●●●●●●●●●●●●
CNVSTE: XBR2.0
AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
166
Rev. 1.4
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