416
CHAPTER 21 400 kHz I
2
C INTERFACE
bit12
MSS:
Master/slave
select bit
This is the master/slave mode selection bit. It can only be set by the user, but it can be
cleared by the user and the hardware.
"0": Go to slave mode
"1": Go to master mode, generate start condition and send address data byte in IDAR
register. It is cleared if an arbitration loss event occurs during master sending.
If a "0" is written to it during a master interrupt (MSS = 1 and INT = 1), the INT bit is
cleared automatically, a stop condition will be generated and the data transfer ends.
Note that the MSS bit is reset immediately, the generation of the stop condition can be
checked by polling the BB bit in the IBSR register.
If a "1" is written to it while the bus is idle (MSS= 0 and BB= 0), a start condition is
generated and the contents of the IDAR register (which should be address data) is sent.
If a "1" is written to the MSS bit while the bus is in use (BB = 1 and TRX= 0 in IBSR;
MSS= 0 in IBCR), the interface waits until the bus is free and then starts sending.
If the interface is addressed as slave with write access (data reception) in the meantime,
it will start sending after the transfer ended and the bus is free again. If the interface is
sending data as slave in the meantime (AAS = 1 and TRX = 1 in IBSR), it will not start
sending data if the bus of free again. It is important to check whether the interface was
addressed as slave (AAS = 1 in IBSR), sent the data byte successfully (MSS = 1 in
IBCR) or failed to send the data byte (AL = 1 in IBSR) at the next interrupt!
bit11
ACK:
Acknowledge bit
This is the acknowledge generation on data byte reception enable bit. It only can be
changed by the user.
"0": The interface will not acknowledge on data byte reception
"1": The interface will acknowledge on data byte reception
This bit is not valid when receiving address bytes in slave mode - if the interface detects
its 7 or 10 bit slave address, it will acknowledge if the corresponding enable bit (ENTB
in ITMK or ENSB in ISMK) is set.
Write access to this bit should occur during an interrupt (INT = 1) or if the bus is idle
(BB= 0 in the IBSR register) only.
bit10
GCAA:
General call
address
acknowledge bit
This bit enables acknowledge generation when a general call address is received. It only
can be changed by the user.
"0": The interface will not acknowledge on general call address byte reception.
"1": The interface will acknowledge on general call address byte reception.
Write access to this bit should occur during an interrupt (INT = 1) or if the bus is idle
(BB= 0 in IBSR register) or the interface is disabled (EN= 0 in ICCR register) only.
bit9
INTE:
Interrupt enable
bit
This bit enables the MCU interrupt generation. It only can be changed by the user.
"0": Interrupt disabled
"1": Interrupt enabled
Setting this bit to "1" enables MCU interrupt generation when the INT bit is set to "1"
(by the hardware).
Table 21.2-2 Function of Each Bit of the Bus Control Register (IBCR) (2/3)
Bit name
Function
Содержание MB90390 Series
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Страница 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
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Страница 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
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Страница 364: ...336 CHAPTER 19 UART0 UART1 ...
Страница 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
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Страница 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
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Страница 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
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