SH7147 Datasheet, PDF (860/1108 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 20 Flash Memory
(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 20.8. Boot mode must be initiated within the ranges of these
system clock frequencies. Note that the internal clock division ratio of ×1/3 is not supported in
boot mode.
Start _{D0 D1 D2 D3 D4 D5 D6}
bit
Measure low period (9 bits) (data is H'00)
D7 ^{Stop bit}
High period of
at least 1 bit
Figure 20.7 Automatic Adjustment Operation of SCI Bit Rate
Table 20.8 Peripheral Clock (Pφ) Frequency that Can Automatically Adjust Bit Rate of
This LSI
Host Bit Rate
Peripheral Clock (Pφ) Frequency Which Can Automatically Adjust LSI's
Bit Rate
9,600 bps
10 to 40 MHz (T_opr = −40 to +85°C)
10 to 32 MHz (T_opr = −40 to +125°C)
19,200 bps
10 to 40 MHz (T = −40 to +85°C)
opr
10 to 32 MHz (T = −40 to +125°C)
opr
Note: The internal clock division ratio of ×1/3 is not supported in boot mode.
Rev. 3.00 Oct. 06, 2008 Page 836 of 1080
REJ09B0230-0300