
I-90
EPSON
S1C62N33 TECHNICAL HARDWARE
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Serial Interface)
Programming notes
(1) If the bit data of SE2 changes while SCLK is in the mas-
ter mode, a hazard will be output to the SCLK pin. If this
poses a problem for the system, be sure to set the SCLK
to the external clock if the bit data of SE2 is to be
changed.
(2) Be sure that read-out of the interrupt factor flag (ISIO) is
done only when the serial port is in the STOP status
(SIOF = "0") and the DI status (interrupt flag = "0"). If
read-out is performed while the serial data is in the RUN
status (during input or output), the data input or output
will be suspended and the initial status resumed. Read-
out during the EI status (interrupt flag = "1") causes
malfunctioning.
(3) When using the serial interface in the master mode, the
synchronous clock uses the CPU system clock. Accord-
ingly, do not change the system clock (fosc1
fosc3)
while the serial interface is operating.
(4) Perform data writing/reading to data registers SD0–SD7
only while the serial interface is halted (i.e., the synchro-
nous clock is neither being input or output).
(5) As a trigger condition, it is required that data writing or
reading on data registers SD0–SD7 be performed prior to
writing "1" to SCTRG. (The internal circuit of the serial
interface is initiated through data writing/reading on
data registers SD0–SD7.) Supply trigger only once every
time the serial interface is placed in the RUN state. More-
over, when the synchronous clock SCLK is external clock,
start to input the external clock after the trigger.
(6) Writing to the interrupt mask registers can be done only
in the DI status (interrupt flag = "0").
Writing during EI status will cause malfunction.
(7) SCTRG resides in the same bit at the same address as
SIOF, and one or the other is selected by write or read
operation. When writing a "1" to SCTRG use the OR
command, and when writing a "0" use the AND com-
mand. No other commands should be used for this pur-
pose.