Filter
Top Products
Section 21 IEBus
TM
Controller
Page 1084 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
21.1.1 IEBus Communications Protocol
An overview of the IEBus is provided below.
Communications method: Half-duplex asynchronous communications
Multi-master system
All units connected to the IEBus can transfer data to other units.
Broadcast communications function (one-to-many communications)
Group broadcast communications: Broadcast communications to group unit
General broadcast communications: Broadcast communications to all units
Mode is selectable (three modes with different transfer speeds)
Table 21.1 Mode Types
Mode
IEB*
1
=
12, 18, 24*
2
, 30, 36 MHz
IEB*
1
= 12.58, 18.87*
2
,
25.16, 31.45 MHz
Maximum Number of
Transfer Bytes (byte/frame)
0 About 3.9 kbps About 4.1 kbps 16
1 About 17 kbps About 18 kbps 32
2 About 26 kbps About 27 kbps 128
Notes: 1. Peripheral clock (P), or clocks for AUDIO_X1 and AUDIO_X2
2. Oscillation frequency when this LSI is used
Access control: CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
Priority of bus mastership is as follows.
Broadcast communications (one-to-many communications) have priority over normal
communications (one-to-one communications).
A smaller master address has priority.
Communications scale
Number of units: Up to 50
Cable length: Up to 150 m (when using a twisted-pair cable)
Note: The communications scale of the actual system depends on the characteristics of the
externally mounted IEBus driver/receiver and the cable used.