MSC8144E Reference Manual, Rev. 3
24-4
Freescale
Semiconductor
I
2
C
The value written to the I2CDFSRR should be defined by the system noise and the I2CFDR
value. I2CDFSRR must be less than six times the division factor defined by I2CFDR. Note that
the division factor stands for a I2CDFSRR value of 1.
24.2.4 Transaction Monitoring
The different conditions of the I
2
C data transfers are monitored as follows:
START conditions are detected when an SDA fall occurs while SCL is high.
STOP conditions are detected when and SDA rise occurs while SCL is high.
Data transfers in progress are canceled when a STOP condition is detected or if there is a
target address mismatch. Cancellation of data transactions resets the clock module
The bus state is busy beginning with the detection of a START condition, and idle when a
STOP condition is detected.
24.2.5 Arbitration Control
The arbitration control block controls the arbitration procedure of the initiator mode. A loss of
arbitration occurs whenever the initiator detects a 0 on the external SDA line while attempting to
drive a 1, tries to generate a START or restart at an inappropriate time, or detects an unexpected
STOP request on the line. Arbitration by the initiator in initiator mode is lost under the following
conditions:
Low detected when high expected (transmit)
Ack bit, low detected when high expected (receive)
A START condition is attempted when the bus is busy
A START condition is attempted when the bus is nearly busy (the I
2
C controller does not
yet recognize the bus as busy, but the bus is set to Initiator mode and SDA samples low).
A start condition is attempted when the requesting device is not the bus owner
Unexpected STOP condition detected
24.2.6 Transfer Control
The I
2
C contains logic that controls the output to the serial data (SDA) and serial clock (SCL)
lines of the I
2
C. The SCL output is pulled low as determined by the internal clock generated in
the clock module. The SDA output can only change at the midpoint of a low cycle of the SCL,
unless performing a START, STOP, or restart condition. Otherwise, the SDA output is held
constant. The SDA signal is pulled low when one or more of the following conditions are true in
either initiator or target mode:
Initiator mode
— data bit (transmit)
— ack bit (receive)
Содержание MSC8144E
Страница 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
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Страница 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
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Страница 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Страница 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Страница 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Страница 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Страница 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Страница 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Страница 884: ...MSC8144E Reference Manual Rev 3 17 44 Freescale Semiconductor RapidIO Interface Dedicated DMA Controller ...
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