h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 469

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

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 and
selection state. The bit-rate-adjustment sequence is shown in figure 14.22.
Communications Protocol:After adjustment of the bit rate, the protocol for communications
between the host and the boot program is as shown below.
1. One-byte commands and one-byte responses
2. n-byte commands or n-byte responses
3. Error response
4. Programming of 128 bytes
5. Memory read response
These commands and responses are comprised of a single byte. These are consists of the
inquiries and the ACK for successful completion.
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.
The error response is a response to inquiries. It consists of an error response and an error code
and comes two bytes.
The size is not specified in commands. The size of n is indicated in response to the
programming unit inquiry.
This response consists of four bytes of data.
Host
Figure 14.22 Bit-Rate-Adjustment Sequence
H'00 (Completion of adjustment)
H'E6 (Boot response)
H'00 (30 times maximum)
(H'FF (error))
H'55
Rev. 2.00, 03/04, page 437 of 534
Boot Program
Measuring the
1-bit length