UPD784938 Datasheet, PDF (473/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 20 IEBus CONTROLLER
Table 20-3. Control Field for Locked Slave Unit
Bit 3
0
0
0
Bit 2
0
1
0
Bit 1
0
0
0
Bit 0
0
0
1
Function
Reads slave status
Reads lock address (low-order 8 bits)
Reads lock address (high-order 4 bits)
If the unlocked unit receives the control data shown in Table 20-4, the unit rejects accepting the control data
and does not output the acknowledge bit.
Table 20-4. Control Field for Unlocked Slave Unit
Bit 3
0
0
Bit 2
1
1
Bit 1
0
0
Bit 0
0
1
Function
Interrupts lock address (low-order 8 bits)
Interrupts lock address (high-order 4 bits)
If one unit occupies the bus as the master, the value set to the control data register (CDR) is output.
Figure 20-4. Control Field
Control field
Control bit (4 bits) Parity ACK
MSB
LSB
(6) Telegraph length field
This field is output by the transmission side to inform the reception side of the number of bytes of the transmit data.
The configuration of the telegraph length field is as shown in Figure 20-5.
Table 20-5 shows the relation between the telegraph length bit and the number of transmit data.
Figure 20-5. Telegraph Length Field
MSB
Telegraph length field
Telegraph length bit (8 bits)
Parity ACK
LSB
Table 20-5. Contents of Telegraph Length Bit
Telegraph Length Bit (Hex)
01H
02H
|
FFH
00H
Number of Transmit Data Bytes
1 byte
2 bytes
|
255 bytes
256 bytes
Preliminary User’s Manual U13987EJ1V0UM00
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