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Chapter 33 I2C Controller
2.I2C Interface Registers
2.1 Bus Control Register (IBCR0)
The bus control register (IBCR0) has the following functions:
• Interrupt enabling flags
• Interrupt generation flag
• Bus error detection flag
• Repeated start condition generation
• Master / slave mode selection
• General call acknowledge generation enabling
• Data byte acknowledge generation enabling
Write access to this register should only occur while the INT=‘1’ or if a transfer is to be started. The user
should not write to this register during an ongoing transfer since changes to the ACK or GCAA bits could result
in bus errors. All bits in this register except the BER and the BEIE bit are cleared if the interface is not enabled
(EN=‘0’ in ICCR0).
[bit 15] BER (Bus ERror)
This bit is the bus error interrupt flag. It is set by the hardware and cleared by the user. It always reads ‘1’ in a
Read-Modify-Write access.
(Write access)
(Read access)
When this bit is set, the EN bit in the ICCR0 register is cleared, the I
2
C interface goes to pause status, data
transfer is interrupted and all bits in the IBSR0 and the IBCR0 registers except BER, BEIE and INT are
cleared. The BER bit must be cleared before the interface may be reenabled.
This bit is set to ‘1’ if:
• start or stop conditions are detected at wrong places: during an address data transfer or during the transfer
of the bits two to nine (acknowledge bit)
• a ten bit address header with read access is received before a ten bit write access
• a stop condition is detected while the interface is in master mode
The detection of the first two of the above conditions is enabled after the reception of the first stop condition to
prevent false bus error reports if the interface is being enabled during an ongoing transfer.
0 Clear bus error interrupt flag.
1 No effect.
0 No bus error detected.
1 One of the error conditions described below detected.
BER BEIE SCC MSS ACK GCAA INTE INT
⇐ Bit no.
Read/write ⇒
(R/W) (R/W) (W) (R/W) (R/W) (R/W) (R/W) (R/W)
Default value⇒
(0) (0) (0) (0) (0) (0) (0) (0)
Bus control register
Address : 0000D0
H
15 14 13 12 11 10 9 8
IBCR0