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Synchronous Serial Interface (SSI)
Freescale Semiconductor
27-53
empty condition, even when the transmitter is disabled by the transmit enable (SSI_CR[TE]) bit. Writing
data to the SSI_TX clears the corresponding TDE bit, thus clearing the interrupt.
Two transmit data interrupts are available (two per channel in two-Channel mode): transmit data with
exception status and transmit data without exceptions.
shows the conditions under which
these interrupts are generated.
27.5
Initialization/Application Information
The following types of reset affected the SSI:
•
Power-on reset—Asserting the RESET signal generates the power-on reset. This reset clears the
SSI_CR[SSI_EN] bit, which disables the SSI. All other status and control bits in the SSI are
affected as described in
•
SSI reset—The SSI reset is generated when the SSI_CR[SSI_EN] bit is cleared. The SSI status bits
are reset to the same state produced by the power-on reset. The SSI control bits, including those in
SSI_CR, are unaffected. The SSI reset is useful for selective reset of the SSI, without changing the
present SSI control bits and without affecting the other peripherals.
The correct sequence to initialize the SSI is:
1. Issue a power-on or SSI reset (SSI_CR[SSI_EN] = 0).
2. Set all control bits for configuring the SSI (refer to
3. Enable appropriate interrupts/DMA requests through SSI_IER.
4. Set the SSI_CR[SSI_EN] bit to enable the SSI.
5. For AC97 mode, set the SSI_ACR[AC97EN] bit after programming the SSI_ATAG register (if
needed, for AC97 fixed mode).
6. Set SSI_CR[TE/RE] bits.
To ensure proper operation of the SSI, use the power-on or SSI reset before changing any of the control
bits listed in
NOTE
These control bits should not be changed when the SSI module is enabled.
Table 27-30. SSI Transmit Data Interrupts
Interrupt
TIE
TUE
n
TFE
n
/TDE
n
Transmit Data 0 Interrupts (
n
= 0)
Transmit Data 1 (with exception status)
1
1
1
Transmit Data 1 (without exception)
1
0
1
Transmit Data 1 Interrupts (
n
= 1)
Transmit Data 0 (with exception status)
1
1
1
Transmit Data 0 (without exception)
1
0
1
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...