Datasheet

Section 7 ROM
Page 184 of 982 REJ09B0465-0300 Rev. 3.00
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
(e) Frequency-Division-Ratio Inquiry
In response to a frequency-division-ratio inquiry command, the boot program returns the
information on the selectable frequency division ratios.
Command H'22
• Command H'22 (1 byte): Frequency-division-ratio inquiry
Response H'32 Size Number
of types
Number of
Frequency
division
ratios
Frequency
division
ratio
…
…
SUM
• Response H'32 (1 byte): Response to a frequency-division-ratio inquiry command
• Size (1 byte): The total size of the number-of-types, number-of-frequency-division-ratios, and
frequency-division-ratio fields.
• Number of types (1 byte): The number of operating clock signals for which frequency division
ratios can be selected for the device.
(For example, the value is H'02 if frequency division ratio settings can be made for the
frequencies of the main and peripheral module operating clock signals.)
• Number of frequency division ratios (1 byte): The number of selectable frequency division
ratios for each operating clock signal.
(For example, the number of selectable frequency division ratios for the main or peripheral
module operating clock signal.)
• Frequency division ratio (1 byte):
The negative numerical value by which the frequency is divided. (Example: H'FE (-2) when
the frequency is divided by two.)
As many frequency-division-ratio fields are repeated as the number of corresponding
frequency division ratios; and the combinations of the former and latter fields are repeated as
many times as the number of types (= number of operating clock signals).
• SUM (1 byte): Checksum