Datasheet

739
SAM9G25 [DATASHEET]
11032C–ATARM–25-Jan-13
37.12.6 TWI Status Register
Name: TWI_SR
Address: 0xF8010020 (0), 0xF8014020 (1), 0xF8018020 (2)
Access: Read-only
Reset: 0x0000F009
• TXCOMP: Transmission Completed (automatically set / reset)
TXCOMP used in Master mode:
0 = During the length of the current frame.
1 = When both holding and shifter registers are empty and STOP condition has been sent.
TXCOMP behavior in Master mode can be seen in Figure 37-8 on page 710 and in Figure 37-10 on page 711.
TXCOMP used in Slave mode
:
0 = As soon as a Start is detected.
1 = After a Stop or a Repeated Start + an address different from SADR is detected.
TXCOMP behavior in Slave mode can be seen in Figure 37-29 on page 727, Figure 37-30 on page 728, Figure 37-31 on page
729 and Figure 37-32 on page 729.
• RXRDY: Receive Holding Register Ready (automatically set / reset)
0 = No character has been received since the last TWI_RHR read operation.
1 = A byte has been received in the TWI_RHR since the last read.
RXRDY behavior in Master mode can be seen in Figure 37-10 on page 711.
RXRDY behavior in Slave mode can be seen in Figure 37-27 on page 726, Figure 37-30 on page 728, Figure 37-31 on page 729
and Figure 37-32 on page 729.
• TXRDY: Transmit Holding Register Ready (automatically set / reset)
TXRDY used in Master mode:
0 = The transmit holding register has not been transferred into shift register. Set to 0 when writing into TWI_THR register.
1 = As soon as a data byte is transferred from TWI_THR to internal shifter or if a NACK error is detected, TXRDY is set at the
same time as TXCOMP and NACK. TXRDY is also set when MSEN is set (enable TWI).
TXRDY behavior in Master mode can be seen in Figure 37.8.4 on page 708.
TXRDY used in Slave mode
:
0 = As soon as data is written in the TWI_THR, until this data has been transmitted and acknowledged (ACK or NACK).
1 = It indicates that the TWI_THR is empty and that data has been transmitted and acknowledged.
31 30 29 28 27 26 25 24
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15 14 13 12 11 10 9 8
EOSACC SCLWS ARBLST NACK
76543210
– OVRE GACC SVACC SVREAD TXRDY RXRDY TXCOMP