PD72042B_15 Datasheet, PDF (17/92 Pages) Renesas Technology Corp – LSI DEVICE FOR Inter Equipment BusTM (IEBusTM) PROTOCOL CONTROL

µPD72042B
2 Master reception
The data-length bits and parity bit are output by the slave unit. When the master unit detects even parity,
the master unit outputs the acknowledge signal.
If the master unit detects odd parity, the master unit does not output an acknowledge signal, regarding the
received data-length bits as being incorrect. Then, the master unit enters the standby state again. At this
time, the slave unit also enters the standby state again, and communication terminates.
(6) Data field
The data field is used for data transmission and reception to and from a slave unit.
The master unit uses the data field to transmit data to the slave unit, or to receive data from the slave unit.
The data field consists of data bits, a parity bit, and an acknowledge bit.
The eight data bits are output, starting with the MSB.
After the data bits have been output, the parity bit and acknowledge bit are output from the master unit and slave
unit, respectively.
Broadcast is performed only when the master unit transmits data. At this time, any acknowledge signal is ignored.
The operations related to master transmission and master reception are explained below.
1 Master transmission
When the master unit performs a write to a slave unit, the master unit transmits the data bits and a parity
bit to the slave unit. The slave unit receives the data bits and parity bit, then outputs an acknowledge signal
if even parity is detected and the reception buffer is empty. If odd parity is detected, or if the reception buffer
is not empty, the slave unit rejects the corresponding data, and does not output an acknowledge signal.
If no acknowledge signal is received from the slave unit, the master unit transmits the same data
again. The master unit repeats this operation until it receives an acknowledge signal from the slave unit,
or until the data exceeds the maximum number of transmission bytes.
When even parity is detected, and an acknowledge signal is received from the slave unit, the master unit
transmits the subsequent data, if any, and provided the maximum number of transmission bytes is not
reached.
For broadcast, an acknowledge signal is not output by any slave unit. The master unit transfers data one
byte at a time.
2 Master reception
When the master unit reads data from a slave unit, the master unit outputs a synchronization signal for each
bit as it is read.
The slave unit outputs data and a parity bit to the bus according to the synchronization signal output by the
master unit.
The master unit reads the data and parity bit output by the slave unit, and checks the parity.
If the master unit detects odd parity, or if the reception buffer is not empty, the master unit rejects the data,
and does not output an acknowledge signal. The master unit repeats the read operation for the same data
provided the maximum allowable number of transmission bytes per communication frame has not been
reached.
If the master unit confirms even parity, and the reception buffer is empty, the master unit accepts the data,
and returns an acknowledge signal to the slave unit. Then, the master unit reads the next data, provided
the maximum allowable number of transmission bytes per frame has not been reached.
Data Sheet S13990EJ3V0DS
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