HMS81C2012A Datasheet, PDF (69/107 Pages) List of Unclassifed Manufacturers – CMOS Single-Chip 8-Bit Microcontroller with A/D Converter & VFD Driver

HMS81C2012A/2020A
14.2 The method of Serial I/O
① Select transmission/receiving mode
Note: When external clock is used, the frequency should
be less than 1MHz and recommended duty is 50%.
② In case of sending mode, write data to be send to SIOR.
③ Set SIOST to “1” to start serial transmission.
Note: If both transmission mode is selected and transmis-
sion is performed simultaneously it would be made error.
④ The SIO interrupt is generated at the completion of SIO
and SIOSF is set to “1”. In SIO interrupt service routine,
correct transmission should be tested.
⑤ In case of receiving mode, the received data is acquired
by reading the SIOR.
14.3 The Method to Test Correct Transmission
Serial I/O Interrupt
Service Routine
0
SIOSF
1
SE = 0
Abnormal
Write SIOM
0
SR
1
Normal Operation
Overrun Error
- SE : Interrupt Enable Register Low IENL(Bit3)
- SR : Interrupt Request Flag Register Low IRQL(Bit3)
Figure 14-5 Serial Method to Test Transmission
SEP. 2004 Ver 2.00
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