SH7261 datasheet(914/1348 Pages) RENESAS

914 / 1348 page

Section 20 IEBus

TM Controller (IEB) [R5S72612] [R5S72613]

Rev. 2.00 Sep. 07, 2007 Page 882 of 1312

REJ09B0320-0200

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Slave Address Field

The slave address field is a field to transmit an address (the slave address) of a unit (the slave unit)

to be transmitted. The slave address field is comprised of slave address bits, a parity bit, and an

acknowledge bit.

The slave address consists of 12 bits and the MSB is output first. The parity bit is output after the

12-bit slave address is transmitted to avoid receiving the slave address accidentally. The master

unit then detects the acknowledgement from the slave unit to confirm that the slave unit exists on

the bus. When the acknowledgement is detected, the master unit enters the control field output

state. However, the master unit enters the control field output state without detecting the

acknowledgement in broadcast communications.

The slave unit returns an acknowledgement when the slave addresses match and the parities of the

master and slave addresses are correct. When the parity of either the master or slave address is

incorrect, the slave unit decides that the master or slave address was not correctly received and

does not return the acknowledgement. In this case, the master unit enters the waiting (monitor)

state and communications ends.

In the case of broadcast communications, the slave address is used to identify the type of broadcast

communications (group or general) as follows:

• When the slave address is H'FFF: General broadcast communications

• When the slave address is other than H'FFF: Group broadcast communications

Note:

The group number is the upper 4-bit value of the slave address in group broadcast

communications.

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Control Field

The control field is a field for transmitting the type and direction of the following data field. The

control field is comprised of control bits, a parity bit, and an acknowledge bit.

The control bits consist of four bits and the MSB is output first.

The parity bit is output following the control bits. When the parity is correct, and the slave unit

can implement the function required from the master unit, the slave unit returns an

acknowledgement and enters the message length field output state. However, if the slave unit

cannot implement the requirements from the master unit even though the parity is correct, or if the

parity is not correct, the slave unit does not return an acknowledgement and returns to the waiting

(monitor) state.

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