M16C80 Datasheet, PDF (307/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

M16C/80 Group
32. Standard serial I/O mode
32.1 Overview of standard serial I/O mode 1 (clock synchronized)
In standard serial I/O mode 1, software commands, addresses and data are input and output between the
MCU and peripheral units (serial programer, etc.) using 4-wire clock-synchronized serial I/O (UART1).
Standard serial I/O mode 1 is engaged by releasing the reset with the P65 (CLK1) pin "H" level.
In reception, software commands, addresses and program data are synchronized with the rise of the trans-
fer clock that is input to the CLK1 pin, and are then input to the MCU via the RxD1 pin. In transmission, the
read data and status are synchronized with the fall of the transfer clock, and output from the TxD1 pin.
The TxD1 pin is for CMOS output. Transfer is in 8-bit units with LSB first.
When busy, such as during transmission, reception, erasing or program execution, the RTS1 (BUSY) pin is
"H" level. Accordingly, always start the next transfer after the RST1 (BUSY) pin is "L" level.
Also, data and status registers in memory can be read after inputting 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 software commands, status
registers, etc.
Rev.1.00 Aug. 02, 2005 ^{Page 296} of 329
REJ09B0187-0100