UPD72042BGT NEC [NEC], UPD72042BGT Datasheet - Page 19

• Manufacturer Part Number: UPD72042BGT
• Description: LSI DEVICE FOR Inter Equipment Bus (IEBus) PROTOCOL CONTROL
• Manufacturer: NEC [NEC]

(2) Data/command transfer (control bits: Read (3H, 7H), write (AH, BH, EH, FH))
Notes 1. The slave transmission buffer is accessed during a data read operation (control bits: 3H, 7H).
Remarks 1. The user can select data and commands as necessary according to the system.
When data read (3H, 7H) is set, the data in the data buffer of the slave unit is read into the master unit.
When data write (BH, FH) or command write (AH, EH) is set, the data received by the slave unit is processed
according to the operation specifications for the slave unit.
2. The slave reception buffer is accessed during a data write operation (control bits: 8H, AH, BH, EH, FH).
3. The value of bit 4 can be selected by using the UAR1 register.
4. Bits 7 and 6 are currently fixed to 10 in the hardware of the PD72042B.
For the PD72042B, this buffer corresponds to the TBF available when STRQ of the FLG register is set
to 1.
For the PD72042B, this buffer corresponds to the RBF available when SLRE of the FLG register is set
to 1.
2. 3H, AH, and BH may cause locking, depending on the communication conditions and status.
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 7
Bit 6
MSB
bit 7
Note 1
Note 2
Note 3
Bit
bit 6
Value
00
01
10
11
0
1
0
1
0
1
0
0
1
0
Fig. 2-2 Slave Status (SSR) Bit Format
Table 2-5 Slave Status Meanings
bit 5
The slave transmission buffer is empty.
The slave transmission buffer is not empty.
The slave reception buffer is empty.
The slave reception buffer is not empty.
The unit is not locked.
The unit is locked.
Fixed at 0
Slave transmission disabled
Slave transmission enabled
Fixed at 0
Mode 0
Mode 1
Reserved for future expansion
Data Sheet S13990EJ3V0DS
bit 4
bit 3
Meaning
bit 2
Indicates the highest
mode supported by the
unit
Note 4
bit 1
.
bit 0
LSB
PD72042B
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