AM186ES Advanced Micro Devices, AM186ES Datasheet - Page 64

• Manufacturer Part Number: AM186ES
• Description: microcontrollers provide a low-cost/ high-performance solution for embedded system designers who wish to use the x86 architecture.
• Manufacturer: Advanced Micro Devices

4.1.2
Figure 4-2
4-4
Reset Configuration Register
(RESCON, Offset F6h)
The Reset Configuration (RESCON) register (see Figure 4-2) in the peripheral control block
latches system-configuration information that is presented to the processor on the address/
data bus (AD15–AD0 for the 186 or AO15–AO8 and AD7–AD1 for the 188) during the rising
edge of reset. The interpretation of this information is system-specific. The processor does
not impose any predetermined interpretation, but simply provides a means for
communicating this information to software.
When the RES input is asserted Low, the contents of the address/data bus are written into
the Reset Configuration register. The system can place configuration information on the
address/data bus using weak external pullup or pulldown resistors, or using an external
driver that is enabled during reset. The processor does not drive the address/data bus
during reset.
For example, the Reset Configuration register could be used to provide the software with
the position of a configuration switch in the system. Using weak external pullup and pulldown
resistors on the address and data bus, the system could provide the microcontroller with
a value corresponding to the position of a jumper during a reset.
Reset Configuration Register
The value of the RESCON register is system-dependent.
Bits 15–0: Reset Configuration (RC)—There is a one-to-one correspondence between
address/data bus signals during the reset and the Reset Configuration register’s bits. On
the Am186ES microcontroller, AD15 corresponds to bit 15 of the Reset Configuration
register, and so on. On the Am188ES microcontroller, AO15 corresponds to register bit 15
and AD7 corresponds to bit 7. Once RES is deasserted, the Reset Configuration register
holds its value. This value can be read by software to determine the configuration
information.
The contents of the Reset Configuration register are read-only and remain valid until the
next processor reset.
15
Peripheral Control Block
RC
7
0