FSDEF=B_0x0, FSOFF=B_0x0, FSPOL=B_0x0
SAI frame configuration register
| FRL | Frame length. These bits are set and cleared by software. They define the audio frame length expressed in number of SCK clock cycles: the number of bits in the frame is equal to FRL[7:0] + 1. The minimum number of bits to transfer in an audio frame must be equal to 8, otherwise the audio block behaves in an unexpected way. This is the case when the data size is 8 bits and only one slot 0 is defined in NBSLOT[4:0] of SAI_xSLOTR register (NBSLOT[3:0] = 0000). In master mode, if the master clock (available on MCLK_x pin) is used, the frame length should be aligned with a number equal to a power of 2, ranging from 8 to 256. When the master clock is not used (NODIV = 1), it is recommended to program the frame length to an value ranging from 8 to 256. These bits are meaningless and are not used in AC97 or SPDIF audio block configuration. They must be configured when the audio block is disabled. |
| FSALL | Frame synchronization active level length. These bits are set and cleared by software. They specify the length in number of bit clock (SCK) + 1 (FSALL[6:0] + 1) of the active level of the FS signal in the audio frame These bits are meaningless and are not used in AC97 or SPDIF audio block configuration. They must be configured when the audio block is disabled. |
| FSDEF | Frame synchronization definition. This bit is set and cleared by software. When the bit is set, the number of slots defined in the SAI_xSLOTR register has to be even. It means that half of this number of slots are dedicated to the left channel and the other slots for the right channel (e.g: this bit has to be set for I2S or MSB/LSB-justified protocols…). This bit is meaningless and is not used in AC97 or SPDIF audio block configuration. It must be configured when the audio block is disabled. 0 (B_0x0): FS signal is a start frame signal 1 (B_0x1): FS signal is a start of frame signal + channel side identification |
| FSPOL | Frame synchronization polarity. This bit is set and cleared by software. It is used to configure the level of the start of frame on the FS signal. It is meaningless and is not used in AC97 or SPDIF audio block configuration. This bit must be configured when the audio block is disabled. 0 (B_0x0): FS is active low (falling edge) 1 (B_0x1): FS is active high (rising edge) |
| FSOFF | Frame synchronization offset. This bit is set and cleared by software. It is meaningless and is not used in AC97 or SPDIF audio block configuration. This bit must be configured when the audio block is disabled. 0 (B_0x0): FS is asserted on the first bit of the slot 0. 1 (B_0x1): FS is asserted one bit before the first bit of the slot 0. |