H8SSLASH2225 datasheet(577/1071 Pages) RENESAS

577 / 1071 page

Section 14 IEBus™ Controller (IEB) [H8S/2258 Group]

Rev. 5.00 Aug 08, 2006 page 491 of 982

REJ09B0054-0500

acknowledgement. The master unit reads in the subsequent data if the number of data does not

exceed the maximum number of transfer bytes in one frame.

(7) Parity Bit

The parity bit is used to confirm that transfer data has no error.

The parity bit is added to respective data of the master address, slave address, control, message

length, and data bits.

The even parity is used. When the number of one bits in data is odd, the parity bit is 1. When the

number of one bits in data is even, the parity bit is 0.

(8) Acknowledge Bit

In normal communications (a single unit to a single unit communications), the acknowledge bit is

added to the following position in order to confirm that data is correctly accepted.

• At the end of the slave address field

• At the end of the control field

• At the end of the message length field

• At the end of the data field

The acknowledge bit is defined below.

• 0: indicates that the transfer data is acknowledged. (ACK)

• 1: indicates that the transfer data is not acknowledged. (NAK)

Note that the acknowledge bit is ignored in the case of broadcast communications.

(a) Acknowledge bit at the End of the Slave Address Field

The acknowledge bit at the end of the slave address field becomes NAK in the following cases

and transfer is stopped.

 When the parity of the master address or slave address bits is incorrect

 When a timing error (an error in bit format) occurs

 When there is no slave unit

(b) Acknowledge bit at the End of the Control Field

The acknowledge bit at the end of the control field becomes NAK in the following cases and

transfer is stopped.

 When the parity of the control bits is incorrect

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