
Synchronous Serial Interface (SSI)
Freescale Semiconductor
24-41
The following settings are done automatically by the processor when in I
2
S slave mode:
•
Normal mode is selected (SSI_CR[NET] = 0)
•
Tx frame sync length set to one-bit-long-frame (SSI_TCR[TFSL] = 1)
•
Rx frame sync length set to one-bit-long-frame (SSI_RCR[RFSL] = 1)
•
Tx shifting w.r.t. bit 0 of TXSR (SSI_TCR[TXBIT0] = 1)
•
Rx shifting w.r.t. bit 0 of RXSR (SSI_RCR[RXBIT0] = 1)
Set the SSI_CCR[WL, DC] bits to configure the data transmission.
The word length is variable in I
2
S slave mode and the WL bits determine the number of bits that contain
valid data. The actual word length is determined by the external codec. The external I
2
S master sends a
frame sync according to the I
2
S protocol (early, word wide, and active low). The SSI internally operates
so each frame sync transition is the start of a new frame (the WL bits determine the number of bits to be
transmitted/received). After one data word has been transferred, the SSI waits for the next frame sync
transition to start operation in the next time slot. Transmit and receive mask bits should not be used in I
2
S
slave mode.
24.4.1.5
AC97 Mode
In AC97 mode, SSI transmits a 16-bit tag slot at the start of a frame and the rest of the slots (in that frame)
are all 20-bits wide. The same sequence is followed while receiving data. Refer to the AC97 specification
for details regarding transmit and receive sequences and data formats.
NOTE
Since the SSI has only one RxDATA pin, only one codec is supported.
Secondary codecs are not supported.
When AC97 mode is enabled, the hardware internally overrides the following settings. The programmed
register values are not changed by entering AC97 mode, but they no longer apply to the module’s
operation. Writing to the programmed register fields updates their values. These updates can be seen by
reading back the register fields. However, these settings do not take effect until AC97 mode is turned off.
The register bits within the bracket are equivalent settings.
•
Synchronous mode is entered (SSI_CR[SYN] = 1)
•
Network mode is selected (SSI_CR[NET] = 1)
•
Tx shift direction is msb transmitted first (SSI_TCR[TSHFD] = 0)
•
Rx shift direction is msb received first (SSI_RCR[RSHFD] = 0)
•
Tx data is clocked at rising edge of the clock (SSI_TCR[TSCKP] = 0)
•
Rx data is latched at falling edge of the clock (SSI_RCR[RSCKP] = 0)
•
Tx frame sync is active high (SSI_TCR[TFSI] = 0)
•
Rx frame sync is active high (SSI_RCR[RFSI] = 0)
•
Tx frame sync length is one-word-long-frame (SSI_TCR[TFSL] = 0)
•
Rx frame sync length is one-word-long-frame (SSI_RCR[RFSL] = 0)
•
Tx frame sync initiated one bit before data is transmitted (SSI_TCR[TEFS] = 1)
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...