
Synchronous Serial Interface (SSI)
Freescale Semiconductor
24-31
24.4.1.1
Normal Mode
Normal mode is the simplest mode of the SSI. It transfers data in one time slot per frame. A time slot is a
unit of data and the WL bits define the number of bits in a time slot. In continuous clock mode, a frame
sync occurs at the beginning of each frame. The following factors determine the length of the frame:
•
Period of the serial bit clock (DIV2, PSR, PM bits for internal clock or the frequency of the external
clock on the SSI_BCLK port)
•
Number of bits per time slot (WL bits)
•
Number of time slots per frame (DC bits)
If normal mode is configured with more than one time slot per frame, data transfers only in the first time
slot of the frame. No data transfers in subsequent time slots. In normal mode, DC values corresponding to
more than a single time slot in a frame only result in lengthening the frame.
24.4.1.1.1
Normal Mode Transmit
Conditions for data transmission from the SSI in normal mode are:
1. SSI enabled (SSI_CR[SSI_EN] = 1)
2. Enable FIFO and configure transmit and receive watermark if the FIFO is used.
3. Write data to transmit data register (SSI_TX0)
4. Transmitter enabled (TE = 1)
5. Frame sync active (for continuous clock case)
6. Bit clock begins (for gated clock case)
When the above conditions occur in normal mode, the next data word transfers into the transmit shift
register (TXSR) from the transmit data register 0 (SSI_TX0) or from the transmit FIFO 0 register, if
enabled. The new data word transmits immediately.
If transmit FIFO 0 is not enabled and the transmit data register empty (TDE0) bit is set, a transmit
interrupt 0 occurs if the TIE and SSI_IER[TDE0] bits are set.
If transmit FIFO 0 is enabled and the transmit FIFO empty (TFE0) bit is set, transmit interrupt 0 occurs if
the TIE and SSI_IER[TFE0] bits are set. If transmit FIFO 0 is enabled and filled with data, eight data
words can be transferred before the core must write new data to the SSI_TX0 register.
The SSI_TXD port is disabled except during the data transmission period. For a continuous clock, the
optional frame sync output and clock outputs are not disabled, even if receiver and transmitter are disabled.
24.4.1.1.2
Normal Mode Receive
Conditions for data reception from the SSI are:
1. SSI enabled (SSI_CR[SSI_EN] = 1)
2. Enable receive FIFO (optional)
3. Receiver enabled (RE = 1)
4. Frame sync active (for continuous clock case)
5. Bit clock begins (for gated clock case)
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...