IA186EB/IA188EB
8-Bit/16-Bit Microcontrollers
Data Sheet
July 10, 2011
4.1.7
I/O Port Unit
The I/O Port Unit (IPU) on the IA186EB/IA188EB supports two 8-bit channels of input, output,
or input/output operation. Port 1 is multiplexed with the chip select pins and is output only.
Most of Port 2 is multiplexed with the serial channel pins.
4.1.8
Refresh Control Unit
The Refresh Control Unit (RCU) automatically generates a periodic memory read bus cycle to
keep dynamic or pseudo-static memory refreshed. A 9-bit counter controls the number of clocks
between refresh requests.
A 12-bit address generator is maintained by the RCU and is presented on the a1–a12 address
lines during the refresh bus cycle. Address Bits [a13–a19] are programmable to allow the refresh
address block to be located on any 8-Kbyte boundary.
4.1.9
Power Management Unit
The IA186EB/IA188EB Power Management Unit (PMU) is provided to control the power
consumption of the device. The PMU provides three power modes: Active, Idle, and
Powerdown.
Active Mode indicates that all units on the IA186EB/IA188EB are functional and the device
consumes maximum power (depending on the level of peripheral operation). Idle Mode freezes
the clocks of the execution and bus units at a logic zero state (all peripherals continue to operate
normally).
The Powerdown mode freezes all internal clocks at a logic zero level and disables the crystal
oscillator. All internal registers hold their values provided V
CC
is maintained. Current
consumption is reduced to just transistor junction leakage.
4.2
Peripheral Architecture
The IA186EB/IA188EB has integrated several common system peripherals with a CPU core to
create a compact, yet powerful system. The integrated peripherals are designed to be flexible
and provide logical interconnections between supporting units (e.g., the interrupt control unit
supports interrupt requests from the timer/counters or serial channels). The list of integrated
peripherals includes:
7-Input Interrupt Control Unit
3-Channel Timer/Counter Unit
2-Channel Serial Communications Unit
10-Output Chip-Select Unit
I/O Port Unit
Refresh Control Unit
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