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Document # 001-20559 Rev. *D
Digital Blocks
Figure 17-17. Typical SPIM Timing in Mode 2 and 3
Status Generation and Interrupts.
There are four status
bits in an SPI Block: TX Reg Empty, RX Reg Full, SPI Com-
plete, and Overrun.
TX Reg Empty indicates that a new byte can be written to
the TX Buffer register. When the block is enabled, this status
bit is immediately asserted. This status bit is cleared when
the user writes a byte of data to the TX Buffer register. TX
Reg Empty is a control input to the state machine and, if a
transmission is not already in progress, the assertion of this
control signal initiates one. This is the default SPIM block
interrupt. However, an initial interrupt is not generated when
the block is enabled. The user must write a byte to the TX
Buffer register and that byte must be loaded into the shifter
before interrupts generated from the TX Reg Empty status
bit are enabled.
RX Reg Full is asserted on the edge that captures the eighth
bit of receive data. This status bit is cleared when the user
reads the RX Buffer register (DR2).
SPI Complete is an optional interrupt and is generated when
eight bits of data and clock have been sent. In modes 0 and
1, this occurs one-half cycle after RX Reg Full is set;
because in these modes, data is latched on the leading
edge of the clock and there is an additional one-half cycle
remaining to complete that clock. In modes 2 and 3, this
occurs at the same edge that the receive data is latched.
This signal may be used to read the received byte or it may
be used by the SPIM to disable the block after data trans-
mission is complete.
Overrun status is set if RX Reg Full is still asserted from a
previous byte when a new byte is about to be loaded into the
RX Buffer register. Because the RX Buffer register is imple-
mented as a latch, Overrun status is set one-half bit clock
before RX Reg Full status.
See
for status timing relationships.
INTERNAL CLOCK
TX REG EMPTY
D7
MOSI
D6
D5
D2
D1
D0
D7
User writes first
byte to the TX
Buffer register.
Shifter is loaded
with the first byte.
User writes next
byte to the TX
Buffer register.
SCLK (MODE 2)
Shifter is loaded
with the next
byte.
Last bit of received
data is valid on this
edge and is latched
into RX Buffer.
CLK INPUT
Free running,
internal bit rate
clock is CLK input
divided by two.
Set up time
for the TX
Buffer write.
SCLK (MODE 3)
RX REG FULL
First input bit
is latched.
First Shift
Содержание PSoC CY8C23533
Страница 4: ...Contents Overview 4 Document 001 20559 Rev D Section G Glossary 385 Index 401 ...
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Страница 24: ...24 Document 001 20559 Rev D Section A Overview ...
Страница 30: ...30 Document 001 20559 Rev D Pin Information ...
Страница 54: ...54 Document 001 20559 Rev D Supervisory ROM SROM ...
Страница 60: ...60 Document 001 20559 Rev D RAM Paging ...
Страница 68: ...68 Document 001 20559 Rev D Interrupt Controller ...
Страница 76: ...12 Document 001 20559 Rev D General Purpose IO GPIO ...
Страница 82: ...18 Document 001 20559 Rev D Internal Main Oscillator IMO ...
Страница 84: ...20 Document 001 20559 Rev D Internal Low Speed Oscillator ILO ...
Страница 90: ...26 Document 001 20559 Rev D External Crystal Oscillator ECO ...
Страница 94: ...30 Document 001 20559 Rev D Phase Locked Loop PLL ...
Страница 106: ...42 Document 001 20559 Rev D Sleep and Watchdog ...
Страница 228: ...164 Document 001 20559 Rev D Section D Digital System ...
Страница 234: ...170 Document 001 20559 Rev D Array Digital Interconnect ADI ...
Страница 278: ...214 Document 001 20559 Rev D Digital Blocks ...
Страница 296: ...232 Document 001 20559 Rev D Analog Interface ...
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Страница 308: ...244 Document 001 20559 Rev D Analog Input Configuration ...
Страница 312: ...248 Document 001 20559 Rev D Analog Reference ...
Страница 338: ...274 Document 001 20559 Rev D Section F System Resources ...
Страница 354: ...290 Document 001 20559 Rev D Multiply Accumulate MAC ...
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Страница 400: ...336 Document 001 20559 Rev D Section G Glossary ...