SD186ES/SD186EM Advanced Micro Devices, SD186ES/SD186EM Datasheet - Page 22

• Manufacturer Part Number: SD186ES/SD186EM
• Description: SD186ES/SD186EM Demonstration Board Users Manual
• Manufacturer: Advanced Micro Devices

Clock and Reset Logic
Am186 Expansion Interface
2-10
The Am186ES and Am186EM microcontrollers can be configured for either 1x
or ½x clock mode. As configured on the SD186ES/SD186EM demonstration
board, the microcontroller is in 1x clock mode. The input is generated by a 40-MHz
fundamental mode crystal (Y1) that is connected to the X1/X2 inputs of the
microcontrollers, resulting in a 40-MHz system clock.
System reset is controlled by a voltage supply supervisor (TI TL7705A, U1). This
device generates the processor’s reset input, asserting the Am186ES or Am186EM
microcontroller’s RES pin for 13 ms when the RESET switch is depressed. The voltage
supply supervisor also holds reset active when the power falls below 4.75 V.
The SD186ES/SD186EM demonstration board supports the PC/104 form-factor
expansion-type connector for additional prototyping and testing. The traditional
PC/104 signals are not present on the board; however, the Am186 expansion
interface enables you to attach wirewrap or prototype boards that have the same
standard physical interface. The pinout of the expansion interface for the SD186ES
is shown in the figures that follow.
NOTE: The pinout of the expansion interface is identical for both the SD186ES
and SD186EM demonstration boards except for the four pins shown in Table 2-2.
Table 2-2. Expansion Interface SD186ES/SD186EM Pinout
SD186ES/SD186EM Demonstration Board User’s Manual
J2 Pin Number
B19
B20
B21
B22
Differences
SD186ES Pin Name
RXD0
TXD0
RTS0
CTS0
SD186EM Pin Name
SDEN0
SDEN1
SDATA
SCLK