400
CHAPTER 22 I
2
C
■
Stop Condition
The master can release the bus and end communications by generating a stop condition. Changing the
SDA0 line from "L" to "H" while SCL0 is "H" generates a stop condition. This signals to the other devices
on the bus that the master has finished communications (referred to below as "bus free"). However, the
master can continue to generate start conditions without generating a stop condition. This is called a
repeated start condition.
Writing "0" to the IBCR10:MSS bit during an interrupt while in bus master mode (IBCR10:MSS = 1,
IBSR0:BB = 1, IBCR10:INT = 1, and IBCR00:ALF = 0) generates a stop condition and changes to slave
mode. In other cases, writing "0" to the IBCR10:MSS bit is ignored.
■
Arbitration
The interface circuit is a true multi-master bus able to connect multiple master devices. Arbitration occurs
when another master within the system simultaneously transfers data during a master transfer.
Arbitration occurs on the SDA0 line while the SCL0 line is at the "H" level. When the send data is "1" and
the data on the SDA0 line is "L" at the master, this is treated as arbitration lost. In this case, data output is
halted and IBCR00:ALF is set to "1". If this occurs, an interrupt is generated if arbitration lost interrupts
have been enabled (IBCR00:ALE = 1). If IBCR00:ALF is set to "1", the module sets IBCR10:MSS = 0 and
IBSR0:TRX = 0, clears TRX, and goes to slave receive mode.
If IBCR00:ALF is set to "1" when IBSR0:BB = 0, IBCR00:ALF is cleared only by writing "0". If
IBCR00:ALF is set to "1" when IBSR0:BB = 1, IBCR00:ALF is cleared only by clearing IBCR10:INT to
"0".
●
Conditions for generating an arbitration lost interrupt when IBSR0:BB = "0"
When a start condition is generated by the program (by setting the IBCR10:MSS bit to "1") at the timing
shown in Figure 22.7-3 or Figure 22.7-4, interrupt generation (IBCR10:INT bit = 1) is prohibited by
arbitration lost detection (IBCR00:ALF = 1).
•
Conditions (1) in which no interrupt is generated due to arbitration lost
If the program triggers a start condition (by setting the IBCR10:MSS bit to "1") when no start condition has
been detected (IBSR0:BB bit = 0) and the SDA0 and SCL0 line pins are at the "
L
" level.
Figure 22.7-3 Timing Diagram with No Interrupt Generated with IBCR00:ALF = 1
"L"
"L"
1
0
0
SCL0 or SDA0 pin at "L" level
SCL0 pin
SDA0 pin
I
2
C operation enabled (ICCR0:EN bit = 1)
Master mode set (IBCR10:MSS bit = 1)
Arbitration lost detection bit
(IBCR00:ALF bit = 1)
Bus busy (IBSR0:BB bit)
Interrupt (IBCR10:INT bit)
Содержание F2 MC-8FX Family
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Страница 30: ...16 CHAPTER 1 DESCRIPTION 1 FPT 64P M23 FPT 64P M24 2 For the I O circuit type refer to 1 8 I O Circuit Type ...
Страница 34: ...20 CHAPTER 1 DESCRIPTION ...
Страница 35: ...21 CHAPTER 2 HANDLING DEVICES This chapter gives notes on using 2 1 Device Handling Precautions ...
Страница 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Страница 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Страница 43: ...29 CHAPTER 4 MEMORY ACCESS MODE This chapter describes the memory access mode 4 1 Memory Access Mode ...
Страница 56: ...42 CHAPTER 5 CPU ...
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Страница 104: ...90 CHAPTER 7 RESET ...
Страница 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
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Страница 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Страница 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
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Страница 382: ...368 CHAPTER 21 UART SIO DEDICATED BAUD RATE GENERATOR ...
Страница 390: ...376 CHAPTER 22 I2C ...
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Страница 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
Страница 476: ...462 CHAPTER 24 LCD CONTROLLER ...
Страница 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
Страница 494: ...480 CHAPTER 26 CLOCK SUPERVISOR ...
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Страница 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
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Страница 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
Страница 595: ...581 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Страница 596: ...582 INDEX Index ...
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Страница 599: ...585 Pin Function Index V2 LCD power supply driving pin 2 439 V3 LCD power supply driving pin 3 439 ...
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