M30222 Datasheet, PDF (225/237 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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MITSUBISHI MICROCOMPUTERS
M30222 Group
Rev. G
Serial I/O Mode 2 (Flash Memory Version)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Standard serial I/O mode 2 (clock asynchronized)
In standard serial I/O mode 2, software commands, addresses and data are input and output between the
MCU and peripheral units (serial programer, etc.) using 2-wire clock-asynchronized serial I/O (UART0).
Standard serial I/O mode 2 is engaged by releasing the reset with the P61 (CLK0) pin "L" level.
The TxD0 pin is for CMOS output. Data transfer is in 8-bit units with LSB first, 1 stop bit and parity OFF.
After the reset is released, connections can be established at 9,600 bps when initial communications
(Figure 1.183) are made with a peripheral unit. However, this requires a main clock with a minimum 2
MHz input oscillation frequency. Baud rate can also be changed from 9,600 bps to 19,200, 38,400 or
57,600 bps by executing software commands. However, communication errors may occur because of the
oscillation frequency of the main clock. If errors occur, change the main clock's oscillation frequency and
the baud rate.
After executing commands from a peripheral unit that requires time to erase and write data, as with erase
and program commands, allow a sufficient time interval or execute the read status command and check
how processing ended, before executing the next command.
Data and status registers in memory can be read after transmitting software commands. Status, such as
the operating state of the flash memory or whether a program or erase operation ended successfully or
not, can be checked by reading the status register. Here following are explained initial communications
with peripheral units, how frequency is identified and software commands.
Initial communications with peripheral units
After the reset is released, the bit rate generator is adjusted to 9,600 bps to match the oscillation frequency of the
main clock, by sending the code as prescribed by the protocol for initial communications with peripheral units
(Figure 1.83).
(1) Transmit "B016" from a peripheral unit. If the oscillation frequency input by the main clock is 10 MHz, the MCU
with internal flash memory outputs the "B016" check code. If the oscillation frequency is anything other than 10
MHz, the MCU does not output anything.
(2) Transmit "0016" from a peripheral unit 16 times. (The MCU with internal flash memory sets the bit rate generator
so that "0016" can be successfully received.)
(3) The MCU with internal flash memory outputs the "B016" check code and initial communications end success-
fully (see Note). Initial communications must be transmitted at a speed of 9,600 bps and a transfer interval of a
minimum 15 ms. Also, the baud rate at the end of initial communications is 9,600 bps.
Note: If the peripheral unit cannot receive "B016" successfully, change the oscillation frequency of the main clock.
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