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Section 21 IEBus
TM
Controller
Page 1086 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
(2) Communications Mode
The IEBus has three communications modes with different transfer speeds. Table 21.2 shows the
transfer speed in each communications mode and the maximum number of transfer bytes in one
communications frame.
Table 21.2 Transfer Speed and Maximum Number of Transfer Bytes in Each
Communications Mode
Communications
Mode
Maximum Number
of Transfer Bytes
(bytes/frame)
Effective Transfer Speed*
1
(kbps)
IEB*
2
=
12, 18, 24*
3
, 30, 36 MHz
IEB*
2
= 12.58, 18.87*
3
,
25.16, 31.45 MHz
0 16 About 3.9 About 4.1
1 32 About 17 About 18
2 128 About 26 About 27
Notes: Each unit connected to the IEBus should select a communications mode prior to
performing communications. Note that correct communications is not guaranteed if the
master and slave units do not adopt the same communications mode.
In the case of communications between a unit with IEB = 6 MHz and a unit with IEB =
6.29 MHz, correct communications are not possible even if the same communications
mode is adopted. Communications must be done with the same oscillation frequency.
1. Effective transfer speed when the maximum number of transfer bytes is transmitted.
2. Peripheral clock (P), or clocks for AUDIO_X1 and AUDIO_X2
3. Oscillation frequency when this LSI is used
(3) Communications Address
In the IEBus, a specific 12-bit communications address is allocated to each individual unit. A
communications address is configured as follows.
Upper four bits: group number (number identifying a group to which the unit belongs)
Lower eight bits: unit number (number identifying individual units in a group)