D12320VF25V Datasheet, PDF (801/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 17 ROM
(3) Operating frequency error
Operating frequency is calculated from the received value of the input frequency and the
multiplication or division ratio. The input frequency is input to the LSI and the LSI is operated at
the operating frequency. The expression is given below.
Operating frequency = Input frequency × Multiplication ratio , or
Operating frequency = Input frequency ÷ Division ratio
The calculated operating frequency should be checked to ensure that it is within the range of
minimum to maximum frequencies which are available with the clock modes of the specified
device. When it is out of this range, an operating frequency error is generated.
(4) Bit rate
Peripheral operating clock (φ), bit rate (B), clock select (CKS) in the serial mode register (SMR).
The error as calculated by the method below is checked to ensure that it is less than 4%. When it
is 4% or more, a bit-rate selection error is generated.
Error (%) = {[
φ * 10⁶
] − 1} * 100
(N+1) * B * 64 * 2^(2*n−1)
When the new bit rate is selectable, the rate will be set in the register after sending ACK in
response. The host will send an ACK with the new bit rate for confirmation and the boot program
will response with that rate.
Confirmation H'06
• Confirmation, H'06, (1 byte): Confirmation of a new bit rate
Response H'06
• Response, H'06, (1 byte): Response to confirmation of a new bit rate
The sequence of new bit-rate selection is shown in figure 17.85.
Rev.7.00 Feb. 14, 2007 page 767 of 1108
REJ09B0089-0700