STM32W108C8

Serial interfaces
STM32W108C8
receive frame segment is determined with the SC_TWIACK bit in the SCx_TWICTRL2
register.
Figure 9.
I 2 C segment transitions
IDLE
START Segment
STOP Segment
TRANSMIT Segment
NO
received ACK ?
YES
RECEIVE Segment
with NACK
RECEIVE Segment
with ACK
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_DATA register.
To initiate (re)start and stop segments, set the SC_TWISTART or SC_TWISTOP bit in the
SCx_TWICTRL1 register, then wait until the bit is clear. Alternatively, the SC_TWICMDFIN
bit in the SCx_TWISTAT can be used for waiting.
To initiate a transmit segment, write the data to the SCx_DATA data register, then set the
SC_TWISEND bit in the SCx_TWICTRL1 register, and finally wait until the bit is clear.
Alternatively the SC_TWITXFIN bit in the SCx_TWISTAT register can be used for waiting.
To initiate a receive segment, set the SC_TWIRECV bit in the SCx_TWICTRL1 register, wait
until it is clear, and then read from the SCx_DATA register. Alternatively, the SC_TWIRXFIN
bit in the SCx_TWISTAT register can be used for waiting. Now the SC_TWIRXNAK bit in the
SCx_TWISTAT register indicates if a NACK or ACK was received from an I 2 C slave device.
83/215 Doc ID 018587 Rev 2