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9-20 Intel® PXA255 Processor Developer’s Manual
I
2
C Bus Interface Unit
9.6.3 Read 1 Byte as a Master
1. Load target slave address and R/nW bit in the IDBR. R/nW must be 1 for a read.
2. Initiate the write.
Set ICR[START], clear ICR[STOP], clear ICR[ALDIE], set ICR[TB]
3. When an IDBR Transmit Empty interrupt occurs.
Read ISR: IDBR Transmit Empty (1), Unit busy (1), R/nW bit (1)
4. Write a 1 to the ISR[ITE] bit to clear the interrupt.
5. Initiate the read.
Clear ICR[START], set ICR[STOP], set ICR[ALDIE], set ICR[ACKNAK], set ICR[TB]
6. When an IDBR Receive full interrupt occurs (unit is sending STOP).
Read ISR: IDBR Receive Full (1), Unit Busy (x), R/nW bit (1), ACK/NAK bit (1)
7. Write a 1 to the ISR[IRF] bit to clear the interrupt.
8. Read IDBR data.
9. Clear ICR[STOP] and ICR[ACKNAK] bits
9.6.4 Write 2 Bytes and Repeated Start Read 1 Byte as a Master
1. Load target slave address and R/nW bit in the IDBR. R/nW must be 0 for a write.
2. Initiate the write.
Set ICR[START], clear ICR[STOP], clear ICR[ALDIE], set ICR[TB]
3. When an IDBR Transmit Empty interrupt occurs.
Read ISR: IDBR Transmit Empty (1), Unit Busy (1), R/nW bit (0)
4. Write a 1 to the ISR[ITE] bit to clear interrupt.
5. Load data byte to be transferred in the IDBR.
6. Initiate the write.
Clear ICR[START], clear ICR[STOP], set ICR[ALDIE], set ICR[TB]
7. When an IDBR Transmit Empty interrupt occurs.
Read ISR: IDBR Transmit Empty (1), Unit busy (1), R/nW bit (0)
8. Write a 1 to the ISR[ITE] bit to clear interrupt.
9. Repeat steps 5-8 one time.
10. Load target slave address and R/nW bit in the IDBR. R/nW must be 1 for a read.
11. Send repeated start as a master.
Set ICR[START], clear ICR[STOP], clear ICR[ALDIE], set ICR[TB]
12. When an IDBR Transmit Empty interrupt occurs.
Read ISR: IDBR Transmit Empty (1), Unit busy (1), R/nW bit (1)
13. Write a 1 to the ISR[ITE] bit to clear interrupt.
14. Initiate the read.
Clear ICR[START], set ICR[STOP], set ICR[ALDIE], set ICR[ACKNAK], set ICR[TB]
15. When an IDBR Receive full interrupt occurs (unit is sending stop).
Read ISR: IDBR Receive Full (1), Unit Busy (x), R/nW bit (1), ACK/NAK bit (1)