SH7055S Datasheet, PDF (807/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

(1) SCI Interface Setting by Host
When boot mode is initiated, this LSI measures the low period of asynchronous SCI-
communication data (H'00), which is transmitted consecutively by the host. The SCI
transmit/receive format is set to 8-bit data, 1 stop bit, and no parity. This LSI calculates the bit
rate of transmission by the host by means of the measured low period and transmits the bit
adjustment end sign (1 byte of H'00) to the host. The host must confirm that this bit adjustment
end sign (H'00) has been received normally and transmits 1 byte of H'55 to this LSI. When
reception is not executed normally, boot mode is initiated again (reset) and the operation
described above must be executed. The bit rate between the host and this LSI is not matched
because of the bit rate of transmission by the host and system clock frequency of this LSI. To
operate the SCI normally, the transfer bit rate of the host must be set to 9,600 bps or 19,200
bps.
The system clock frequency which can automatically adjust the transfer bit rate of the host and
the bit rate of this LSI is shown in table 22.8. Boot mode must be initiated in the range of this
system clock.
Start _{D0 D1 D2 D3 D4 D5 D6}
bit
D7 ^{Stop bit}
Measure low period (9 bits) (data is H'00)
High period of
at least 1 bit
Figure 22.7 Automatic Adjustment Operation of SCI Bit Rate
Table 22.8 System Clock Frequency that Can Automatically Adjust Bit Rate of This LSI
Host Bit Rate
9,600 bps
19,200 bps
System Clock Frequency Which Can Automatically Adjust LSI's Bit Rate
20 to 40 MHz (input frequency of 5 to 10 MHz)
20 to 40 MHz (input frequency of 5 to 10 MHz)
(2) State Transition
The overview of the state transition after boot mode is initiated is shown in figure 22.8. For details
on boot mode, see section 22.10.1, Serial Communications Interface Specification for Boot Mode.
1. Bit rate adjustment
After boot mode is initiated, the bit rate of the SCI interface is adjusted with that of the host.
2. Waiting for inquiry set command
For inquiries about the user-MAT size and configuration, MAT start address, and support
state, the required information is transmitted to the host.
3. Automatic erasure of all user MAT and user boot MAT
After inquiries have finished and a programming/erasing status transition command has been
sent, all of the user MAT and user boot MAT are automatically erased.
Rev.2.0, 07/03, page 769 of 960