M16C62N Datasheet, PDF (196/213 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Mitsubishi microcomputers
M16C / 62N Group (80-pin)
Appendix Standard Serial I/O Mode 2 (Flash Memory Version) ^{SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER}
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 1.32.21) 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 1.32.21).
(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.
Peripheral unit
MCU with internal
flash memory
(1) Transfer "B016"
(2) Transfer "0016" 16 times
1st
At least 15ms
transfer interval
2nd
"B016"
"B016"
"0016"
"0016"
Reset
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.
15 th
16th
"0016"
"0016"
"B016"
(3) Transfer check code "B016"
The bit rate generator setting completes (9600bps)
Figure 1.32.21. Peripheral unit and initial communication
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