P R E L I M I N A R Y
connects to the data inputs and outputs, and the chip
selects connect to the memory chip-select inputs.
COMPARING THE ES TO THE 80C186
Figure 1 shows an example system using a 40-MHz
Am186ES microcontroller. Figure 2 shows a
comparable system implementation with an 80C186.
Because of its superior integration, the Am186ES
microcontroller system does not require the support
devices that are required on the 80C186 example
system. In addition, the Am186ES microcontroller
provides significantly better performance with its 40-
MHz clock rate.
The RD output connects to the SRAM Output Enable
(OE) pin for read operations. Write operations use the
byte-write enables connected to the SRAM Write
Enable (WE) pins.
The example design uses 2-Mbit memory technology
(256 Kbytes) to fully populate the available address
space. Two flash PROM devices provide 512 Kbytes of
nonvolatile program storage, and two static RAM
devices provide 512 Kbytes of data storage area.
X2
X1
BHE
A0
40-MHz
Crystal
SRAM
Am29F200
WE
Flash
WE
WR
ALE
WE
Address
Address
Data
Data
AD15–AD0
OE
OE
RD
UCS
LCS
CS
CS
LATCH
PIOs
RS-232
Level
Converter
Serial
Port
PCS0
Timer 0–2
INT3
INT2–INT0
DMA 0–1
20 MHz
CLKOUT
Figure 2. 80C186 Microcontroller Example System Design
n An option to have all MCS space asserted through
COMPARING THE ES TO THE EMTABLE1
MCS0
Compared to the Am186EM and Am188EM
microcontrollers, the Am186ES and Am188ES
microcontrollers have the following additional features:
n On the Am186ES microcontroller, static bus sizing
allows UCS space to use a 16-bit data bus, while
LCS space can be either 8-bit or 16-bit. All non-
UCS and non-LCS memory and I/O accesses can
be 8-bit or 16-bit. This capability is available only on
the Am186ES microcontroller; the Am188ES micro-
controller has a uniform 8-bit access width.
n Two full-featured asynchronous serial ports
n The ability to use DMA to and from the serial ports
n Two additional external interrupt signals
n Enhancements to the watchdog timer to improve its
n The synchronous serial interface is removed
security and functionality
n On the ES, row addresses are not driven on DRAM
n A pulse width demodulation option
refreshes
n A data strobe bus interface option for DEN
Two Asynchronous Serial Ports
n ARDY functionality is changed to allow both edges
of ARDY to be asynchronous to the clock
The Am186ES and Am188ES microcontrollers have
two identical asynchronous serial ports. Each serial
Am186/188ES and Am186/188ESLV Microcontrollers
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