SH7055S Datasheet, PDF (844/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

22.10 Further Information
22.10.1 Serial Communication Interface Specification for Boot Mode
Initiating boot mode enables the boot program to communicate with the host by using the on-chip
SCI. The serial communication interface specifications are shown below.
• Status
The boot program has three states.
(1) Bit-rate-adjustment state
In this state, the boot program adjusts the bit rate to communicate with the host. Initiating boot
mode enables starting of the boot program and entry to the bit-rate-adjustment state. The
program receives the command from the host to adjust the bit rate. After adjusting the bit rate,
the program enters the inquiry/selection state.
(2) Inquiry/Selection state
In this state, the boot program responds to inquiry commands from the host. The device name,
clock mode, and bit rate are selected. After selection of these settings, the program is made to
enter the programming/erasing state by the command for a transition to the
programming/erasing state. The boot program transfers the erasure program to RAM and
erases the user MATs and user boot MATs before the transition.
(3) Programming/erasing state
Programming and erasure by the boot program take place in this state. The boot program is
made to transfer the programming/erasing program to RAM by commands from the host. Sum
checks and blank checks are executed by sending these commands from the host.
These boot program states are shown in figure 22.26.
Rev.2.0, 07/03, page 806 of 960