3886 datasheet(220/380 Pages) RENESAS

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3886 Group User’s Manual

2-103

APPLICATION

2.5 Multi-master I2C-BUS interface

2.5.7 Notes on multi-master I2C-BUS interface

(1)

Read-modify-write instruction

Precautions for read-modify-write instructions, such as SEB and CLB, when used for any of the

registers of the multi-master I2C-BUS interface, are described below.

➀ I2C data shift register (S0: address 001216)

When executing the read-modify-write instruction for this register during transfer, data may become

an unexpected value.

➁ I2C address register (S0D: address 001316)

When the read-modify-write instruction is executed for this register at detecting the STOP condition,

data may become an unexpected value.

q Reason

Because hardware changes the read/write bit (RWB) at detecting the STOP condition.

➂ I2C status register (S1: address 001416)

Do not execute the read-modify-write instruction for this register because all bits of this register

are changed by hardware.

➃ I2C control register (S1D: address 001516)

When the read-modify-write instruction is executed for this register at detecting the START condition

or at completing the byte transfer, data may become an unexpected value.

q Reason

Because hardware changes the bit counter (BC0 to BC2).

➄ I2C clock control register (S2: address 001616)

The read-modify-write instruction can be executed for this register.

➅ I2C START/STOP condition control register (S2D: address 001716)

The read-modify-write instruction can be executed for this register.

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