SH7261 datasheet(915/1348 Pages) RENESAS

915 / 1348 page

Section 20 IEBus

TM Controller (IEB) [R5S72612] [R5S72613]

Rev. 2.00 Sep. 07, 2007 Page 883 of 1312

REJ09B0320-0200

The master unit enters the subsequent message length field output state after confirming the

acknowledgement.

When the acknowledgement is not confirmed, the master unit enters the waiting (monitor) state,

and communications ends. However, in the case of broadcast communications, the master unit

enters the following message length field output state without confirming the acknowledgement.

For details of the contents of the control bit, see table 20.4.

(5)

Message Length Field

The message length field is a field for specifying the number of transfer bytes. The message length

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

The message length has eight bits and the MSB is output first. Table 20.3 shows the number of

transfer bytes.

Table 20.3

Contents of Message Length bits

Message Length bits (Hexadecimal)

Number of Transfer Bytes

H'01

H'02

H'FF

H'00

1 byte

2 bytes

255 bytes

256 bytes

Note:

If a number greater than the maximum number of transfer bytes in one frame is specified,

communications are done in multiple frames depending on the communications mode. In

this case, the message length bits indicate the number of remaining communications data

after the first transfer. In this LSI, the message length bits must be smaller than the

maximum number of transfer bytes in one frame. Set these within the ranges shown below.

Mode 0: 1 to 16 bytes

Mode 1: 1 to 32 bytes

Mode 2: 1 to 128 bytes

This field operation differs depending on the value of bit 3 in the control field: master

transmission (the bit 3 of the control bits is 1) or master reception (the bit 3 of the control bits is

0).

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