M16C26 Datasheet, PDF (212/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

Udenvdeelropment
Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative and subject to change.
Appendix Standard Serial I/O Mode (Flash Memory Version)
M16C/26 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Standard Serial I/O mode
The standard serial I/O mode inputs and outputs the software commands, addresses and data needed to
operate (read, program, erase, etc.) the internal flash memory using the serial I/O port UART1. The serial
I/O mode transfers the data serially in 8-bit units.
The standard serial I/O mode is different from the parallel I/O mode in that the CPU executes a control
program for flash memory rewrite (using the CPU's rewrite mode), rewrite data input and so forth. It is
started when both the P86(CE) pin and the CNVss pin are in “H” level after the reset is released. (In normal
operation mode, set CNVss pin to “L” level.)
Figure 1.22.1 shows the pin connections for the standard serial I/O mode.
There are actually two standard serial I/O modes: mode 1, which is clock synchronized, and mode 2, which
is asynchronized. Standard serial I/O switches between mode 1 (clock synchronous) and mode 2 (clock
asynchronous) depending on the level of CLK1 pin when the reset is released.
To use standard serial I/O mode 1 (clock synchronous), set the CLK1 pin to “H” level and release the reset.
The operation uses the four UART1 pins CLK1, RxD1, TxD1 and RTS1 (BUSY). The CLK1 pin is the transfer
clock input pin through which an external transfer clock is input. The TxD1 pin is for CMOS output. The
RTS1 (BUSY) pin outputs an “L” level when ready for reception and an "H" level when reception starts. In
mode 1, be sure the TXD1 (P67) pin is at high before reset being deasserted.
To use standard serial I/O mode 2 (clock asynchronous), set the CLK1 pin to “L” level and release the reset.
The operation uses the two UART1 pins RxD1 and TxD1.
In the standard serial I/O mode, only the user ROM area indicated in Figure 1.19.1 can be rewritten. In
addition, a 7-byte ID code exists to protect the device. When there is data in the flash memory, commands
sent from the peripheral unit are not accepted unless the ID code matches.
206
Renesas Technology Corp.