R01UH0822EJ0100 Rev.1.00
Page 724 of 1041
Jul 31, 2019
RX13T Group
24. I
2
C-bus Interface (RIICa)
24.
I
2
C-bus Interface (RIICa)
This MCU has a single-channel I
2
C-bus interface (RIIC).
The RIIC module conforms with the NXP I
2
C-bus (Inter-IC bus) interface and provides a subset of its functions.
In this section, “PCLK” is used to refer to PCLKB.
24.1
Overview
lists the specifications of the RIIC,
shows a block diagram of the RIIC, and
shows
an example of I/O pin connections to external circuits (I
2
C-bus configuration example).
lists the I/O pins of
the RIIC.
Table 24.1
RIIC Specifications (1/2)
Item
Description
Communications format
I
2
C-bus format or SMBus format
Master mode or slave mode selectable
Automatic securing of the various setup times, hold times, and bus-free times for the transfer rate
Transfer rate
Fast-mode is supported (up to 400 kbps)
SCL clock
For master operation, the duty cycle of the SCL clock is selectable in the range from 4 to 96%.
Issuing and detecting
conditions
Start, restart, and stop conditions are automatically generated. Start conditions (including restart conditions)
and stop conditions are detectable.
Slave address
Up to three different slave addresses can be set.
7-bit and 10-bit address formats are supported (along with the use of both at once).
General call addresses, device ID addresses, and SMBus host addresses are detectable.
Acknowledgment
For transmission, the acknowledge bit is automatically loaded.
Transfer of the next data for transmission can be automatically aborted on detection of a
not-acknowledge bit.
For reception, the acknowledge bit is automatically transmitted.
If a wait between the eighth and ninth clock cycles has been selected, software control of the value in the
acknowledge field in response to the received value is possible.
Wait function
In reception, the following periods of waiting can be obtained by holding the SCL clock at the low level:
Waiting between the eighth and ninth clock cycles
Waiting between the ninth clock cycle and the first clock cycle of the next transfer
SDA output delay
function
Timing of the output of transmitted data, including the acknowledge bit, can be delayed.
Arbitration
For multi-master operation
Operation to synchronize the SCL clock in cases of conflict with the SCL signal from another master is
possible.
When issuing the start condition would create conflict on the bus, loss of arbitration is detected by testing
for non-matching between the internal signal for the SDA line and the level on the SDA line.
In master operation, loss of arbitration is detected by testing for non-matching between the signal on the
SDA line and the internal signal for the SDA line.
Loss of arbitration due to detection of the start condition while the bus is busy is detectable (to prevent the
issuing of double start conditions).
Loss of arbitration in transfer of a not-acknowledge bit due to the internal signal for the SDA line and the
level on the SDA line not matching is detectable.
Loss of arbitration due to non-matching of internal and line levels for data is detectable in slave
transmission.
Timeout function
The internal timeout function is capable of detecting long-interval stop of the SCL clock.
Noise cancellation
The interface incorporates digital noise filters for both the SCL and SDA signals, and the width for noise
cancellation by the filters is adjustable by software.
Interrupt sources
Four sources:
Error in transfer or occurrence of events
Detection of arbitration, NACK, timeout, a start condition including a restart condition, or a stop condition
Receive data full (including matching with a slave address)
Transmit data empty (including matching with a slave address)
Transmit end