Figure 20.20 Bit-Rate-Adjustment Sequence - Renesas H8S/2437 Hardware Manual

(2) Bit-Rate-Adjustment State
The bit rate is calculated by measuring the period of transfer of a low-level byte (H'00) from the
host. The bit rate can be changed by the command for a new bit rate selection. After the bit rate
has been adjusted, the boot program enters the inquiry/selection state. The bit-rate-adjustment
sequence is shown in figure 20.20.
Host
(3) Communication Protocol
After adjustment of the bit rate, the protocol for serial communications between the host and the
boot program is as shown below.
1. One-Byte Commands and One-Byte Responses
These commands and responses are comprised of a single byte. These are consists of the
inquiries and the ACK for successful completion.
2. n-Byte Commands or n-Byte Responses
These commands and responses are comprised of n bytes of data. These are selections and
responses to inquiries.
The amount of programming data is not included under this heading because it is determined
in another command.
3. Error Response
The error response is a response to inquiries. It consists of two bytes: an error response and an
error code.
4. Programming of 128 Bytes
The size is not specified in commands. The size is indicated in response to the programming
unit inquiry.
5. Memory Read Response
This response consists of four bytes.
H'00 (30 times maximum)
H'00 (Completion of adjustment)
H'E6 (Boot response)
(H'FF (error))

Figure 20.20 Bit-Rate-Adjustment Sequence

Boot Program
Measuring the
H'55
Rev. 1.00, 09/03, page 585 of 704
1-bit length