UPD72042BGT NEC [NEC], UPD72042BGT Datasheet - Page 45

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

transmission or master reception. SLRC indicates the communication status in slave data transmission, slave
reception, or broadcast reception.
microcomputer according to the setting of the IRS flag of the CMR register.
communication status and slave communication status.
[MARC]
RCR is a one-byte read register used to indicate the IEBus communication status (return code).
RCR consists of two return codes: MARC and SLRC. MARC indicates the communication status in master
The MARC and SLRC flags are set independently, such that the microcomputer can simultaneously read the master
Caution When IRQ is set as a result of a program crash, the previous value of RCR is preserved.
MARC represents a return code issued during master transmission or master reception.
(a) Master transmission
RCR
Return code register
Master transmission is performed when the microcomputer performs the setting explained below.
• Master transmission setting
Table 4-2 lists the MARC return codes for master transmission.
1 In the low-order 4 bits of the MCR register, control bits (1010, 1011, 1110, or 1111) are set for master-
2 In COMC of the CMR register, a command (1000 or 1001) for requesting master communication is set.
to-slave data transfer.
b7
MARC
When the contents of RCR change, an interrupt request is sent to the
Data Sheet S13990EJ3V0DS
b4
b3
SLRC
Address
Read/write
When reset : 11111111B
b0
RCR
: 1000B (8H)
: Read
PD72042B
45