IA186EB/IA188EB
Data Sheet
8-Bit/16-Bit Microcontrollers
July 10, 2011
Table 8. IA188EB Pin/Signal Descriptions (Continued)
Pin
Signal
bclk1
Name
p2.2/bclk1
PLCC
59
LQFP
46
PQFP
9
Description
baud clock, Serial Port 1. Input. The bclk1 pin
can be used to provide an alternate clock
source for Serial Port 1. The input clock rate
cannot be greater than one-half the operating
frequency of the IA188EB.
clkin
clkin
41
28
71
clock input. Input. The clkin pin is the input
connection for an external clock. An external
oscillator, operating at two times the required
processor operating frequency, can be
connected to this pin.
If a crystal is used to supply the clock, it is
connected between the clkin pin and the
oscout pin (see oscout table entry). When a
crystal is connected, it drives an internal Pierce
oscillator to the IA188EB.
clkout
clkout
44
31
74
clock output. Output. The clkout pin provides
a timing reference for inputs and outputs of the
IA188EB. This clock output is one-half the input
clock (clkin) frequency. The clkout signal has
a 50% duty cycle, transitioning every falling
edge of clkin.
cts0_n
cts1_n
den_n
dt/r_n
cts0_n
p2.4/cts1_n
den_n
51
56
11
16
38
43
80
NA
1
6
clear to send, Serial Port 0. Input. Active Low.
When this input is high (i.e., not asserted), data
transmission from Serial Port 0 is inhibited.
When the signal is asserted (low), data
transmission is permitted.
clear to send, Serial Port 1. Input. Active Low.
When this input is high (i.e., not asserted), data
transmission from Serial Port 1 is inhibited.
When the signal is asserted (low), data
transmission is permitted.
data enable. Output. Active Low. This signal
is used to enable of bidirectional transceivers in
a buffered system. The den_n signal is
asserted (low) only when data are to be
transferred on the bus.
data transmit/receive. Output. This signal is
used to control the direction of data flow for
bidirectional buffers in a buffered system.
When dt/r_n is high, the direction indicated is
transmit; when dt/t_n is low, the direction
indicated is receive.
43
NA
dt/r_n
IA211080314-13
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