Renesas H8S/2100 Series, Hardware Manual

Page: 842 / 1024

Section 24 Flash Memory
Rev. 1.00 Apr. 28, 2008 Page 816 of 994
REJ09B0452-0100
(4) Receive Data Check
The methods for checking of receive data are listed below.
1. Input frequency
The received value of the input frequency is checked to ensure that it is within the range of
minimum to maximum frequencies which matches the clock modes of the specified device.
When the value is out of this range, an input-frequency error is generated.
2. Division ratio
The received value of the division ratio is checked to ensure that it matches the clock modes of
the specified device. When the value is out of this range, a division ratio error is generated.
3. Operating frequency error
Operating frequency is calculated from the received value of the input frequency and the
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
÷
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
To facilitate error checking, the value (n) of clock select (CKS) in the serial mode register
(SMR), and the value (N) in the bit rate register (BRR), which are found from the peripheral
operating clock frequency (
φ
) and bit rate (B), are used to calculate the error rate to ensure that
it is less than 4%. If the error is more than 4%, a bit rate error is generated. The error is
calculated using the following expression:
Error (%) = {[ ]
−
1}
×
100
(N + 1)
×
B
×
64
×
2
(2
×
n
−
1)
φ ×
10
6
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, (one byte): Confirmation of a new bit rate
Response H'06
•
Response, H'06, (one byte): Response to confirmation of a new bit rate