M16C80 Datasheet, PDF (314/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

M16C/80 Group
32. Standard serial I/O mode
Lock Bit Disable Command
This command disables the lock bit. The command code “7516” is sent with the 1st byte of the serial
transmission. This command only disables the lock bit function; it does not set the lock bit itself.
However, if an erase command is executed after executing the lock bit disable command, “0” (locked)
lock bit data is set to “1” (unlocked) after the erase operation ends. In any case, after the reset is
cancelled, the lock bit is enabled.
CLK1
RxD1
(M16C reception data)
TxD1
(M16C transmit data)
RTS1(BUSY)
7516
Figure 32.10 Timing for disabling the lock bit
Download Command
This command downloads a program to the RAM for execution. Execute the download command as
explained here following.
(1) Transfer the “FA16” command code with the 1st byte.
(2) Transfer the program size with the 2nd and 3rd bytes.
(3) Transfer the check sum with the 4th byte. The check sum is added to all data sent with the 5th
byte onward.
(4) The program to execute is sent with the 5th byte onward.
When all data has been transmitted, if the check sum matches, the downloaded program is executed.
The size of the program will vary according to the internal RAM.
CLK1
RxD1
(M16C reception data)
TxD1
(M16C transmit data)
RTS1(BUSY)
FA16
Data size (low)
Check
sum
Program ^Program
data
data
Data size (high)
Figure 32.11 Timing for download
Rev.1.00 Aug. 02, 2005 ^{Page 303} of 329
REJ09B0187-0100