SH7261 datasheet(922/1348 Pages) RENESAS

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Section 20 IEBus

TM Controller (IEB) [R5S72612] [R5S72613]

Rev. 2.00 Sep. 07, 2007 Page 890 of 1312

REJ09B0320-0200

(2)

Data Command Transfer (Control Bits: Read (H'3, H'7), Write (H'A, H'B, H'E, H'F))

In the case of data read (H'3, H'7), data in the data buffer of the slave unit is read in the master

unit. In the case of data write (H'B or H'F) or command write (H'A or H'E), data received in the

slave unit is processed in accordance with the operation specification of the slave unit.

Notes: 1. The user can select data and commands freely in accordance with the system.

2. H'3, H'A, or H'B may lock depending on the communications condition and status.

(3)

Locked Address Read (Control Bits: H

′4, H′5)

In the case of the locked address read (H'4 or H'5), the address (12 bits) of the master unit which

issues the lock instruction is configured in bytes as shown in figure 20.3.

SDA

SCL

SLA

1-7

DATA

Figure 20.3 Locked Address Configuration

(4)

Locking/Unlocking (Control Bits: Setting (H'3, H'A, H'B), Cancellation: (H'6))

The lock function is used for message transfer over multiple communications frames. A locked

unit receives data only from the unit which locked it.

Locking and unlocking are described below.

(a)

Locking

When an acknowledge bit of 0 in the message length field is transmitted/received with the control

bits (H'3, H'A, H'B) indicating the lock operation, and then the communications frame is

completed before completion of data transmission/reception for the number of bytes specified by

the message length bits, the slave unit is locked by the master unit. In this case, the bit (bit 2)

relevant to locking in the byte data indicating the slave status is set to 1.

Lock is set only when the number of data exceeds the maximum number of transfer bytes in one

frame. Lock is not set by other error terminations.

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