CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
475
(10)IEBus slave status register (SSR)
This register indicates the communication status of the slave unit. After receiving a slave status transmission
request from the master, the CPU reads this register, and writes a slave status to the IEBus data register
(DR) to transmit the slave status. At this time, the telegraph length is automatically set to “01H” that setting of
the IEBus telegraph length register (DLR) is not required (because it is preset by hardware).
Bits 6 and 7 indicate the highest mode supported by the unit, and are fixed to “01H” (mode 1).
Figure 19-25. IEBus Slave Status Register (SSR) Format
After reset: 41H
R
Address: FFFFF3F2H
7
6
5
<4>
3
<2>
<1>
<0>
SSR
0
1
0
STATSLV
0
STATLOCK
STATRX STATTX
STATSLV
Slave transmission status flag
0
Slave transmission stops
1
Slave transmission enabled
STATLOCK
Lock status flag
0
Unlock status
1
Lock status
STATRX
DR receive status
0
Receiving data not stored in DR
1
Receiving data stored in DR
STATTX
DR transmit status
0
Transmission data not stored in DR
1
Transmission data stored in DR
(a) Slave transmission status flag (STATSLV)...Bit 4
Reflects the contents of slave transmission enable flag.
(b) Lock status flag (STATLOCK)...Bit 2
Reflects the contents of locked flag.
(c) DR reception status (STATRX)...Bit 1
This flag indicates the DR reception state.
(d) DR transmission status (STATTX)...Bit 0
This flag indicates the DR transmission state.
Содержание MPD703030A
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