M30218 Datasheet, PDF (107/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Serial I/O2
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Serial I/O2 Mode
There are two types of serial I/O2 modes: 8-bit serial I/O mode where automatic transfer RAM is not
used, and an automatic transfer serial I/O mode.
(1) 8-bit Serial I/O Mode
Address 034616 is assigned to the serial I/O2 register. When the internal synchronous clock is
selected, a serial transfer of the 8-bit serial I/O is started by a write signal to the serial I/O2 register
(address 034616).
The serial transfer status flag (bit 5 of address 034416) is set to “1” by writing into the serial I/O2
register and reset to “0” after completion of 8-bit transfer. At the same time, a serial I/O2 interrupt
request occurs. If the transfer is completed, the receive data is read out from serial I/O2 register.
When the external synchronous clock is selected, the contents of the serial I/O2 register are con-
tinuously shifted while transfer clocks are input to SCLK21 or SCLK22. Therefore, the clock needs to
be controlled externally.
(2) Automatic Transfer Serial I/O Mode
Address 034616 is assigned to the transfer counter (1-byte units). The serial I/O2 automatic trans-
fer controller controls the write and read operations of the serial I/O2 register. The serial I/O auto-
matic transfer RAM is mapped to addresses 0040016 to 004FF16. Before starting transfer, make
sure the 8 low-order bits of the address that contains the beginning data to be serially transferred is
set to the automatic transfer data pointer (address 034016).
When the internal synchronous clock is selected, the transfer interval is inserted between one data
and another in the following cases:
1. When using no handshake signal
2. When using the SRDY2 output, SBUSY2 output, and SSTB2 output of the handshake signal inde
pendently
3. When using a combination of SRDY2 output and SSTB2 output or a combination of SBUSY2 output
and SSTB2 output of the handshake signal
The transfer interval can be set in the range of 2 to 23 cycles using the automatic transfer interval
set bit (bits 0–4 of address 034816 ).
Also, when using SBUSY2 output as a signal for each occurrence of the all transfer data, a transfer
interval is inserted before the system starts sending or receiving the first data and after the system
finished sending or receiving the last data, not just between one data and another.
Furthermore, when using SSTB2 output, the transfer interval between each 1-byte data is extended
by 2 cycles from the set value no matter how the SBUSY2 output. SSTB2 output function select bit (bit
4 of address 034416) is set.
When using SBUSY2 output and SSTB2 output in combination as a signal for each occurrence of the
all transfer data, the transfer interval after the system finished sending or receiving the last data is
extended by 2 cycles from the set value.
When an external synchronous clock is selected, the automatic transfer interval is disabled.
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