IA186EM/IA188EM
Data Sheet
8-Bit/16-Bit Microcontrollers
February 25, 2011
4.
Device Architecture
A functional block diagram of the IA186EM/IA188EM is shown in Figure 7. This
microcontroller consists of the following functional blocks.
Bus Interface and Control (BIC)
Peripheral Control and Registers
Chip Selects and Control (CSC)
Programmable I/O
Clock and Power Management
DMA
Interrupt Controller
Timers
Asynchronous Serial Ports
Synchronous Serial Interface
4.1
Bus Interface and Control
BIC manages all accesses to external memory and external peripherals. These peripherals may
be mapped either in memory space or I/O space. The BIC supports both multiplexed and non-
multiplexed bus operations. Multiplexed address and data are provided on the ad15–ad0 bus,
while a non-multiplexed address is provided on the a19–a0 bus. The a bus provides address
information for the entire bus cycle (t1–t4), while the ad bus provides address information only
during the first phase of the bus cycle (t1). For more details regarding bus cycles, see the AC
waveforms at the end of this datasheet.
The IA186EM microcontroller provides two signals that serve as byte write enables, write high
byte (whb_n) and write low byte (wlb_n). The IA188EM microcontroller requires only a single
write byte (wb_n) signal to support its 8-bit data bus. The whb_n is the logical OR of the bhe_n
and wr_n. The wlb_n is the logical OR of ad0 and wr_n. The wlb_n is the logical OR of ad0
and wr_n. The wb_n is low whenever a byte is written to the IA188EM data bus ad7–ad0.
The byte write enables are driven in conjunction with the non-multiplexed address bus a19–a0 to
support the timing requirements of common SRAMs.
The BIC also provides support for PSRAM devices. PSRAM is supported in only the lower chip
select (lcs_n) area. In order to support PSRAM, the CSC must be appropriately programmed
(see Section 4.7, Chip Selects).
®
IA211050831-19
UNCONTROLLED WHEN PRINTED OR COPIED
http://www.Innovasic.com
Customer Support:
Page 43 of 146
1-888-824-4184
INNOVASIC [ INNOVASIC, INC ]
