Renesas RL78 Series User Manual page 613

RL78/G1D
The meanings of <1> to <6> in (a) Start condition ~ address ~ data in Figure 14-32 are explained below.
<1> The start condition trigger is set by the master device (STTn = 1) and a start condition (i.e. SCLAn = 1 changes
SDAAn from 1 to 0) is generated once the bus data line goes low (SDAAn). When the start condition is
subsequently detected, the master device enters the master device communication status (MSTSn = 1). The
master device is ready to communicate once the bus clock line goes low (SCLAn = 0) after the hold time has
elapsed.
<2> The master device writes the address + W (transmission) to the IICA shift register n (IICAn) and transmits the
slave address.
<3> In the slave device if the address received matches the address (SVAn value) of a slave device
device sends an ACK by hardware to the master device. The ACK is detected by the master device (ACKDn =
1) at the rising edge of the 9th clock.
<4> The master device issues an interrupt (INTIICAn: end of address transmission) at the falling edge of the 9th
clock. The slave device whose address matched the transmitted slave address sets a wait status (SCLAn = 0)
and issues an interrupt (INTIICAn: address match)
<5> The master device writes the data to transmit to the IICAn register and releases the wait status that it set by the
master device.
<6> If the slave device releases the wait status (WRELn = 1), the master device starts transferring data to the slave
device.
Note If the transmitted address does not match the address of the slave device, the slave device does not return
an ACK to the master device (NACK: SDAAn = 1). The slave device also does not issue the INTIICAn
interrupt (address match) and does not set a wait status. The master device, however, issues the INTIICAn
interrupt (end of address transmission) regardless of whether it receives an ACK or NACK.
Remarks 1. <1> to <15> in Figure 14-32 represent the entire procedure for communicating data using the I
bus.
Figure 14-32 (a) Start condition ~ address ~ data shows the processing from <1> to <6>, Figure 14-
32 (b) Address ~ data ~ data shows the processing from <3> to <10>, and Figure 14-32 (c) Data ~
data ~ stop condition shows the processing from <7> to <15>.
2. n = 0
R01UH0515EJ0120 Rev.1.20
Dec 16, 2016
CHAPTER 14 SERIAL INTERFACE IICA
Note
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Note
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