STM32W108CB datasheet(117/278 Pages) STMICROELECTRONICS

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STM32W108HB STM32W108CC STM32W108CB STM32W108CZ

Serial interfaces

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Full I2C frames have to be constructed by software from individual I2C segments. All

necessary segment transitions are shown in Figure 11. ACK or NACK generation of an I2C

receive frame segment is determined with the ACK bit in the SCx_I2CCR2 register.

Figure 11.

I2C segment transitions

Generation of a 7-bit address is accomplished with one transmit segment. The upper 7 bits

of the transmitted character contain the 7-bit address. The remaining lower bit contains the

command type ("read" or "write").

Generation of a 10-bit address is accomplished with two transmit segments. The upper 5

bits of the first transmit character must be set to 0x1E. The next 2 bits are for the 2 most

significant bits of the 10-bit address. The remaining lower bit contains the command type

("read" or "write"). The second transmit segment is for the remaining 8 bits of the 10-bit

address.

Transmitted and received characters are accessed through the SCx_DR register.

To initiate (re)start and stop segments, set the START or STOP bit in the SCx_I2CCR1

be used for waiting.

To initiate a transmit segment, write the data to the SCx_DR data register, then set the BTE

bit in the SCx_I2CCR1 register, and finally wait until the bit is clear. Alternatively the BTF bit

in the SCx_I2CSR register can be used for waiting.

To initiate a receive segment, set the BRE bit in the SCx_I2CCR1 register, wait until it is

clear, and then read from the SCx_DR register. Alternatively, the BRF bit in the SCx_

NACK or ACK was received from an I2C slave device.

RECEIVE Segment

with NACK

RECEIVE Segment

with ACK

IDLE

START Segment

STOP Segment

TRANSMIT Segment

received ACK ?

YES

STM32W108CB Datasheet(PDF) 117 Page - STMicroelectronics