44.8.7 Data Format

The data framing format of both the transmitter and the receiver are programmable through the Transmitter Frame Mode Register (SSC_TFMR) and the Receive Frame Mode Register (SSC_RFMR). In either case, the user can independently select the following parameters:

  • Event that starts the data transfer (START)
  • Delay in number of bit periods between the start event and the first data bit (STTDLY)
  • Length of the data (DATLEN)
  • Number of data to be transferred for each start event (DATNB)
  • Length of synchronization transferred for each start event (FSLEN)
  • Bit sense: most or least significant bit first (MSBF)

Additionally, the transmitter can be used to transfer synchronization and select the level driven on the TD pin while not in data transfer operation. This is done respectively by the Frame Sync Data Enable (FSDEN) and by the Data Default Value (DATDEF) bits in SSC_TFMR.

Table 44-2. Data Frame Registers
Transmitter Receiver Field Length Comment
SSC_TFMR SSC_RFMR DATLEN Up to 32 Size of word
SSC_TFMR SSC_RFMR DATNB Up to 16 Number of words transmitted in frame
SSC_TFMR SSC_RFMR MSBF Most significant bit first
SSC_TFMR SSC_RFMR FSLEN Up to 256 Size of Synchro data register
SSC_TFMR DATDEF 0 or 1 Data default value ended
SSC_TFMR FSDEN Enable send SSC_TSHR
SSC_TCMR SSC_RCMR PERIOD Up to 512 Frame size
SSC_TCMR SSC_RCMR STTDLY Up to 255 Size of transmit start delay
Figure 44-16. Transmit and Receive Frame Format in Edge/Pulse Start Modes

In the example illustrated above, the SSC_THR is loaded twice. The FSDEN value has no effect on the transmission. SyncData cannot be output in Continuous mode.

Figure 44-17. Transmit Frame Format in Continuous Mode (STTDLY = 0)
Figure 44-18. Receive Frame Format in Continuous Mode (STTDLY = 0)