PD72042B_15 Datasheet, PDF (47/92 Pages) Renesas Technology Corp – LSI DEVICE FOR Inter Equipment BusTM (IEBusTM) PROTOCOL CONTROL

µPD72042B
RCR
Return code register
Address : 1000B (8H)
Read/write : Read
When reset : 11111111B
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
transmission or master reception. SLRC indicates the communication status in slave data transmission, slave
reception, or broadcast reception. When the contents of RCR change, an interrupt request is sent to the
microcomputer according to the setting of the IRS flag of the CMR register.
The MARC and SLRC flags are set independently, such that the microcomputer can simultaneously read the master
communication status and slave communication status.
b7
b4
b3
MARC
SLRC
b0
RCR
Caution When IRQ is set as a result of a program crash, the previous value of RCR is preserved.
[MARC]
MARC represents a return code issued during master transmission or master reception.
(a) Master transmission
Master transmission is performed when the microcomputer performs the setting explained below.
• Master transmission setting
1 In the low-order 4 bits of the MCR register, control bits (1010, 1011, 1110, or 1111) are set for master-
to-slave data transfer.
2 In COMC of the CMR register, a command (1000 or 1001) for requesting master communication is set.
Table 4-2 lists the MARC return codes for master transmission.
Data Sheet S13990EJ3V0DS
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