Renesas H8S/2111B 用户手册

Rev. 1.00, 05/04, page 335 of 544 

 

The IIC has a function for forcible initialization of its internal state if a deadlock occurs during 
communication. 

Initialization is executed in accordance with the setting of bits CLR3 to CLR0 in DDCSWR or 
clearing ICE bit. For details on the setting of bits CLR3 to CLR0, see section 13.3.7, DDC Switch 
Register (DDCSWR). 

Scope of Initialization: The initialization executed by this function covers the following items: 

•  ICDRE and ICDRF internal flags 
•  Transmit/receive sequencer and internal operating clock counter 
•  Internal latches for retaining the output state of the SCL and SDA pins (wait, clock, data 

output, etc.) 

 

The following items are not initialized: 

•  Actual register values (ICDR, SAR, SARX, ICMR, ICCR, ICSR, ICXR (except for the ICDRE 

and ICDRF flags), and PGCTL) 

•  Internal latches used to retain register read information for setting/clearing flags in ICMR, 

ICCR, and ICSR 

•  The value of the ICMR bit counter (BC2 to BC0) 
•  Generated interrupt sources (interrupt sources transferred to the interrupt controller) 

 

•  Interrupt flags and interrupt sources are not cleared, and so flag clearing measures must be 

taken as necessary. 

•  Basically, other register flags are not cleared either, and so flag clearing measures must be 

taken as necessary. 

•  When initialization is executed by DDCSWR, the write data for bits CLR3 to CLR0 is not 

retained. To perform IIC clearance, bits CLR3 to CLR0 must be written to simultaneously 
using an MOV instruction. Do not use a bit manipulation instruction such as BCLR. 

•  Similarly, when clearing is required again, all the bits must be written to simultaneously in 

accordance with the setting. 

•  If a flag clearing setting is made during transmission/reception, the IIC module will stop 

transmitting/receiving at that point and the SCL and SDA pins will be released. When 
transmission/reception is started again, register initialization, etc., must be carried out as 
necessary to enable correct communication as a system.