3804H Datasheet, PDF (91/116 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

3804 Group (Spec. H)
q Standard serial I/O Mode
The standard serial I/O mode inputs and outputs the software
commands, addresses and data needed to operate (read, pro-
gram, erase, etc.) the internal flash memory. This I/O is clock
synchronized serial. This mode requires a purpose-specific pe-
ripheral unit.
The standard serial I/O mode is different from the parallel I/O
mode in that the CPU controls flash memory rewrite (uses the
CPU rewrite mode), rewrite data input and so forth. The standard
serial I/O mode is started by connecting “H” to the CNVss pin and
“H” to the P45 (BOOTENT) pin, and releasing the reset operation.
(In the ordinary microcomputer mode, set CNVss pin to “L” level.)
This control program is written in the Boot ROM area when the
product is shipped from Renesas. Accordingly, make note of the
fact that the standard serial I/O mode cannot be used if the Boot
ROM area is rewritten in parallel I/O mode. The standard serial I/
O mode has standard serial I/O mode 1 of the clock synchronous
serial and standard serial I/O mode 2 of the clock asynchronous
serial. Tables 17 and 18 show description of pin function (standard
serial I/O mode). Figures 87 to 90 show the pin connections for
the standard serial I/O mode.
In standard serial I/O mode, only the User ROM area shown in
Figure 77 can be rewritten. The Boot ROM area cannot be written.
In standard serial I/O mode, a 7-byte ID code is used. When there
is data in the flash memory, this function determines whether the
ID code sent from the peripheral unit (programmer) and those writ-
ten in the flash memory match. The commands sent from the
peripheral unit (programmer) are not accepted unless the ID code
matches.
Rev.1.01 Jan 25, 2005 page 91 of 114
REJ03B0131-0101Z