
CHAPTER 18 IEBus CONTROLLER
User’s Manual U16541EJ4V0UD
686
18.5 Interrupt Request Signal Generation Timing and Main CPU Processing
18.5.1 Master transmission
Initial preparation processing:
Sets a unit address, slave address, control data, telegraph length, and the first byte of the transmit data.
Communication start processing:
Set the BCR register (enable communication, master request, and slave reception).
Figure 18-26. Master Transmission
Start
Broad-
cast
M address P
S address
P
A
Control
P
A
Telegraph
length
P
A
Data 1
PA
Data 1
Data 2
P
A
Data n – 1
P
A
Data n
P
A
<1>
<2>
Approx. 624
s (mode 1, at 6.29 MHz)
Approx. 390 s
(mode 1, at 6.29 MHz)
<1> Interrupt request signal (INTIE2, INTSTA) occurrence
Judgment of occurrence of error
Note
→
Error processing
↓
Judgment of slave request
→
Slave reception processing
(See 18.5.1 (1) Slave reception processing)
↓
Judgment of arbitration result
→
Remaster request processing
<2> Interrupt request signal (INTIE2, INTSTA) occurrence
Judgment of occurrence of error
Note
→
Error processing
↓
Judgment of end of communication
→
End of communication processing
↓
Judgment of end of frame
→
Recommunication processing
(See 18.5.1 (3) Recommunication processing)
Note
This processing is necessary only when the INTIE2 interrupt request signal is used as the start interrupt,
and is not necessary when the INTSTA interrupt request signal is used (in this case, the error processing
is performed by using the INTERR interrupt request signal).
Remarks 1.
: Interrupt request signal (INTIE1) occurrence (See 18.5.1 (2)
Interrupt request signal
(INTIE1) occurrence)
The transmit data of the second and subsequent bytes is written to the DR register by DMA
transfer.
At this time, the data transfer direction is RAM
→ on-chip peripheral I/O
2.
: An interrupt request signal (INTIE1) does not occur.
3. n = Final number of data bytes