UPD72042 datasheet(47/92 Pages) NEC

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µPD72042

Data Sheet S14870EJ1V0DS00

Table 4-3

MARC Return Codes for Master Communication

MARC

Description

0100

1. Meaning: Master reception has started.

2. Occurrence condition:

1 The unit has won the arbitration to become the master unit, and a communication frame up to the

data-length field was transferred successfully.

2 When the control field is received, RBF becomes ready for receptionNote.

After the data-length field, 0000 is set in MARC, and three-byte data consisting of a slave address,

control bits, and data-length bits is set in RBF. If RBF becomes full when this three-byte data is set,

0001 is set in MARC.

3. Microcomputer processing: Three-byte data consisting of a slave address, control bits, and data-

length bits can be read from RBF.

0101

1. Meaning: The master reception buffer is full.

2. Occurrence condition: This return code is issued when RBF becomes full during data reception as the

master unit, and reception data cannot be set in RBF.

3. Microcomputer processing: If data consisting of one or more bytes is not read from RBF within the

time below, the one-byte data cannot be received, and the

µPD72042 returns an NAK.

• Reception data read time:

Approx. 1570

µs (mode 0)

Approx. 390

µs (mode 1)

0110

1. Meaning: Master reception was terminated normally.

2. Occurrence condition: This return code is issued when as much data as the amount specified in the

data-length field has been received normally in a communication frame. In this case, the MARQ flag of

the FLG register changes from 1 to 0.

3. Microcomputer processing: Reception data can be read from RBF, and the number of bytes of

master reception data can be read from RDR1.

0111

1. Meaning: Master reception was aborted.

2. Occurrence condition: This return code is issued in any of the following cases. In each case, the

MARQ flag of the FLG register changes from 1 to 0.

•

When the unit has lost the arbitration to become the master unit.

•

When a transmission is stopped because the NAK is returned from the slave unit at the end of the

slave address field or the control field of a communication frame or because the NAK is sent to the

slave unit at the end of the data-length field of a communication frame (excluding the broadcast).

•

When a communication is terminated prior to the reception of as much data as the amount specified

in the data-length field of a communication frame.

3. Microcomputer processing: Reception data can be read from RBF, and the number of bytes of

master reception data can be read from RDR1.

Note

See Note of Table 4-9.

UPD72042 Datasheet(PDF) 47 Page - NEC

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