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M30245 Group
Serial I/O Mode
Rev.2.00
Oct 16, 2006
page 208 of 264
REJ03B0005-0200
Standard Serial I/O Mode
The standard serial I/O mode serially inputs and outputs the software commands, addresses and data needed to
operate (read, program, erase, etc.) the internal flash memory. It uses a specific serial programmer to accomplish this.
It is different from the parallel I/O mode because the CPU controls operations like rewriting the flash memory (using the
CPU rewrite mode) and serially inputting data.
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The standard serial I/O mode is entered by clearing the reset with the P50 (CE) pin set to a "H" level, the P55 (EPM) pin
set to a "L" level and the CNVss pin set to a "H" level. (For normal microprocessor mode, set the CNVss pin to "L" level.)
A control program is written in the boot ROM area when the product is shipped from Renesas. The standard serial I/O
mode cannot be used if the boot ROM area is rewritten in the parallel I/O mode. Figure 1.158 shows the pin connections
for the standard serial I/O mode. Table 1.70 lists the pin functions for standard serial IO mode.
There are two standard serial I/O modes that both require a purpose-specific serial programmer: clock synchronous
and clock asynchronous. Standard serial I/O switches between mode 1 (clock synchronous) and mode 2 (clock
asynchronous) according to the level of the CLK1 pin when the reset is released. Serial data I/O uses UART1 and
transfers the data serially in 8-bit units.
To use standard serial I/O mode 1 (clock synchronous):
Set the CLK1 pin to "H" level and release the reset
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This mode 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.
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The RTS1 (BUSY) pin outputs an "L" level when ready for reception and an "H" level when reception starts.
To use standard serial I/O mode 2 (clock asynchronous):
Set the CLK1 pin to "L" level and release the reset.
This mode uses the two UART1 pins RxD1 and TxD1.
In standard serial I/O mode, only the user ROM area indicated in Figure 1.149 can be rewritten. The boot ROM cannot.
The standard serial I/O mode uses a 7-byte ID code. When there is data in the flash memory, commands sent from the
programmer are not accepted unless the ID codes are identical.
ID Code Check Function
The ID code check function can be used in serial I/O mode to protect the contents of the flash memory from being read
out or rewritten. If the contents of the flash memory are not blank, the ID code sent from the serial programmer is
compared with the ID code written in the flash. If the ID codes are not identical, the commands sent from the serial
programmer are not accepted. Figure 1.159 shows the ID code store addresses. The ID code consists of 8-bit data:
(beginning with the first byte) 0FFFDF16, 0FFFE316, 0FFFEB16, 0FFFEF16, 0FFFF316, 0FFFF716, and 0FFFFB16. Write
a program that has the ID code preset at these addresses.