HD6412332 RENESAS [Renesas Technology Corp], HD6412332 Datasheet - Page 840

• Manufacturer Part Number: HD6412332
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Automatic SCI Bit Rate Adjustment: When boot mode is initiated, the H8S/2338 F-ZTAT chip
measures the low period of the asynchronous SCI communication data (H'00) transmitted
continuously from the host. The SCI transmit/receive format should be set as follows: 8-bit data, 1
stop bit, no parity. The chip calculates the bit rate of the transmission from the host from the
measured low period, and transmits one H'00 byte to the host to indicate the end of bit rate
adjustment. The host should confirm that this adjustment end indication (H'00) has been received
normally, and transmit one H'55 byte to the chip. If reception cannot be performed normally,
initiate boot mode again (reset), and repeat the above operations. Depending on the host’s
transmission bit rate and the chip’s system clock frequency, there will be a discrepancy between
the bit rates of the host and the chip. To ensure correct SCI operation, the host’s transfer bit rate
should be set to 9,600 or 19,200 bps.
Table 19.31 shows typical host transfer bit rates and system clock frequencies for which automatic
adjustment of the MCU’s bit rate is possible. The boot program should be executed within this
system clock range.
Table 19.31 System Clock Frequencies for which Automatic Adjustment
Host Bit Rate
19,200 bps
9,600 bps
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REJ09B0245-0400
of H8S/2338 F-ZTAT Bit Rate is Possible
Start
bit
Figure 19.38 Automatic SCI Bit Rate Adjustment
D0
System Clock Frequencies for which Automatic Adjustment
of H8S/2338 F-ZTAT Bit Rate is Possible
16 MHz to 25 MHz
8 MHz to 25 MHz
Low period (9 bits) measured (H'00 data)
D1
D2
D3
D4
D5
D6
D7
(1 or more bits)
High period
Stop
bit