Datasheet

Section 7 ROM
REJ09B0465-0300 Rev. 3.00 Page 177 of 982
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
(1) Bit-Rate Adjustment State
In the bit-rate adjustment state, the boot program measures the low-level period of H'00
transmitted from the host and calculates the bit rate according to the measurement. The bit rate can
be changed using the new-bit-rate selection command. On completion of bit rate adjustment, the
boot program enters the inquiry/selection state. Figure 7.7 shows the sequence of bit rate
adjustment.
Host Boot program
H'00 (30 times max.)
H'E6 (Response)
Measures the length
of nine bits.
H'00 (Adjustment completed)
H'55
H'FF (Error)
Figure 7.7 Sequence of Bit Rate Adjustment
(2) Communication Protocol
1. One-character command or one-character response
A command or response consisting of one character used for inquiry or ACK code indicating a
successful end.
2. n-character command or n-character response
A command or response requiring 128 bytes of data used as a selection command or a response
to an inquiry. The length of programming data is defined separately and so data size (length) is
omitted here.
3. Error response
Response to a command which has caused an error; two bytes, consisting of the error response
and error code.
4. 128-byte programming command
This command does not include its data size information. The data size can be acquired from
the response to the programming-size inquiry command.