IA186EM/IA188EM
8-Bit/16-Bit Microcontrollers
Data Sheet
February 25, 2011
Error detection provided by parity, framing, or overrun errors
Hardware handshaking is achieved with the following selectable control signals:
– Clear to send (cts_n)
– Enable receiver request (enrx_n)
– Ready to send (rts_n)
– Ready to receive (rtr_n)
DMA to and from the port
The port has its own maskable interrupt
The port has an independent baud-rate generator
Maximum baud rate is 1/32 of the processor clock
Transmit and receive lines are double-buffered
In power-save mode the baud rate generator divide factor must be re-programmed to compensate
for the change in clock rate.
4.23
Synchronous Serial Port
The synchronous serial port allows the microcontrollers to communicate with ASICs that are
required to be programmed but have a pin shortage. The four-pin interface allows half-duplex,
bi-directional data transfer at a maximum of 20 Mbits/sec with a 40-MHz CPU clock.
The synchronous serial interface of the IA186EM/ IA188EM operates as the master port in a
master/slave arrangement.
There are four pins in the synchronous serial interface for communication with the system
elements. These pins are two enables (SDEN0 and SDEN1), a clock (SCLK), and a data pin
(SDATA).
In power-save mode, the baud rate generator divide factor must be re-programmed to
compensate for the change in clock rate.
4.24
Programmable I/O (PIO)
Thirty-two pins are programmable as I/O signals (PIO). Table 15 presents them in both numeric
and alphabetic order. Because programming a pin as a PIO disables its normal function, it
should be done only if the normal function is not required. A PIO pin can be programmed as an
input or output with or without a weak pull-up or pull-down. A PIO pin can be also programmed
as an open-drain output. Each PIO pin regains default status after a POR.
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