M30620FCAFP datasheet(257/274 Pages) MITSUBISHI

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Appendix Standard Serial I/O Mode 2 (Flash Memory Version)

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

257

Overview of 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 (UART1).

Standard serial I/O mode 2 is engaged by releasing the reset with the P65 (CLK1) pin "L" level.

The TxD1 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 (Fig-

ure 1.29.22) 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 fre-

quency of the main clock, by sending the code as prescribed by the protocol for initial communications

with peripheral units (Figure 1.29.22).

(1) Transmit "B016" from a peripheral unit. If the oscillation frequency input by the main clock is 10 or 16

MHz, the MCU with internal flash memory outputs the "B016" check code. If the oscillation frequency

is anything other than 10 or 16 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

successfully *1. 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.

*1. If the peripheral unit cannot receive "B016" successfully, change the oscillation frequency of the main clock.

Figure 1.29.22. Peripheral unit and initial communication

MCU with internal

flash memory

Peripheral unit

(1) Transfer "B016"

If the oscillation frequency input

by the main clock is 10 or 16

MHz, the MCU outputs "B016". If

other than 10 or 16 MHz, the

MCU does not output anything.

(2) Transfer "0016" 16 times

At least 15ms

transfer interval

1st

2nd

15 th

16th

(3) Transfer check code "B016"

"B016"

"0016"

"B016"

"0016"

Reset

The bit rate generator setting completes (9600bps)

M30620FCAFP Datasheet(PDF) 257 Page - Mitsubishi Electric Semiconductor

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