ELANSC310 AMD [Advanced Micro Devices], ELANSC310 Datasheet - Page 59

• Manufacturer Part Number: ELANSC310
• Description: Single-Chip, 32-Bit, PC/AT Microcontroller
• Manufacturer: AMD [Advanced Micro Devices]

ALTERNATE PIN FUNCTIONS
To provide the system designer with the most flexibility,
the ÉlanSC310 microcontroller provides a means for
reconfiguring some of the pin functions, depending on
the system requirements. Reconfiguration of the
ÉlanSC310 microcontroller pin functions is accom-
plished in one of two ways, depending on the pin func-
tions that are to be reconfigured. To select the CPU
local bus interface or maximum ISA bus interface, the
state of the DTR and RTS pins are sampled on the ris-
ing edge of the RESIN and IORESET signals when
power is first applied to the ÉlanSC310 microcontroller.
This is shown in Figure 8.
After power has been initially applied and RESIN and
IORESET are deasserted, additional assertions of
IORESET while RESIN = 1 will not cause the pin con-
figurations to change. However, the pin configuration
inputs are always sampled in response to RESIN as-
sertions. Table 26 shows the pin states at reset to en-
able the two different pin configurations involving the
Local Bus and Maximum ISA Bus. The bus configura-
Notes:
This is shown to illustrate when CFG0 and CFG1 are sampled and is not intended to be used for reset timings. For reset timings,
refer to Table 45 on page 88.
RESIN and
IORESET
VCC
DTR
RTS
Figure 8. Bus Option Configuration Select
Élan™SC310 Microcontroller Data Sheet
DTR and RTS sampled at
the rising edge of RESIN and IORESET
P R E L I M I N A R Y
tion selected can be read in bits 5–6 of the Memory
Configuration 1 Register, Index 66h, after the reset.
.
The second method of reconfiguring ÉlanSC310 micro-
controller pin functions is accomplished by program-
ming the internal configuration registers. This method
is used to configure the following functions:
Local Bus
Full/Maximum ISA
DRAM or SRAM main memory interface
Unidirectional or bidirectional parallel port
Clock source driving the X1OUT[BAUDOUT] pin
14.336-MHz clock
Bus Selected
Table 26. Bus Option Select Bit Logic
DTR/CFG1
1
1
RTS/CFG0
0
1
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