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C8051F02X Datasheet, PDF (166/272 Pages) Silicon Laboratories – 8K ISP FLASH MCU Family | |||
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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 â16. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP
XRAMâ 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
â
RX0
â
UART0EN: XBR0.2
SCK
ââ
MISO
MOSI
ââ
ââ
SPI0EN: XBR0.1
NSS
â
â
SDA
âââ
SCL
ââ
â
ââ
SMB0EN: XBR0.0
TX1
âââ
RX1
ââ
ââ
â âââ
UART1EN: XBR2.2
CEX0
â
â
â
â âââ
CEX1
ââ
â âââââ
CEX2
ââ
â âââââ
PCA0ME: XBR0.[5:3]
CEX3
â
â âââââââ
CEX4
â
â âââââââ
ECI
âââââ
âââââââââââ
ECI0E: XBR0.6
CP0
âââââ
ââââââââââââ
CP0E: XBR0.7
CP1
âââââ
âââââââââââââ
CP1E: XBR1.0
T0
âââââ
ââââââââââââââ
T0E: XBR1.1
/INT0 â â â â â
âââââââââââââââ
INT0E: XBR1.2
T1
âââââ
ââââââââââââââââ
T1E: XBR1.3
/INT1 â â â â â
âââââââââââââââââ
INT1E: XBR1.4
T2
âââââ
ââââââââââââââââââ
T2E: XBR1.5
T2EX â â â â â
âââââââââââââââââââ
T2EXE: XBR1.6
T4
âââââ
ââââââââââââââââââââ
T4E: XBR2.3
T4EX â â â â â
âââââââââââââââââââââ
T4EXE: XBR2.4
/SYSCLK â â â â â
ââââââââââââââââââââââ
SYSCKE: XBR1.7
CNVSTR â â â â â
âââââââââââââââââââââââ
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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