SBAS495D June 2010 – August 2021 PCM9211
PRODUCTION DATA
The PCM9211 has two integrated sampling frequency calculators. The first calculator is always connected to the output of the DIR. It calculates the actual sampling frequency of the incoming S/PDIF signal. The result can be read from a register, or output through the MPIO pins. Note that this process is not the same as reading the Channel Status value for the sample rate that the transmitting equipment may be sending.
To use this function, a 24.576-MHz clock source must be supplied to the XTI pin. The 24.576-MHz clock is used as a reference clock to calculate the incoming S/PDIF sampling frequency. If the XTI pin is connected to DGND, the function is disabled and the calculation is not performed. If there is an error in the XTI clock frequency, the calculation result and range will be incorrect.
The result is decoded into 4-bit data and stored in Register 39h/SFSOUT[3:0]; the MPIO pins are then assigned to the SFSOUT[3:0] function.
The data in the SFSOUT[3:0] register (and available as a signal for the MPIO section) are the calculated sampling frequency based on the incoming S/PDIF stream, and not what is reported in Channel Status bits 24 to 27. If the PLL becomes unlocked, or attempts to run out of range, SFSOUT[3:0] = '0000' is output, and indicates abnormal operation.
If the XTI source clock is not supplied before the PCM9211 powers up, SFSOUT [3:0] outputs '0000'. If the XTI source clock is stopped, the fS calculator holds its most recent calculated result. Once the XTI source clock is restored, the fS calculator resumes operation.
Register 39h/SFSST indicates the calculator status. Before reading SFSOUT[3:0], it is recommended that the user verify that the SFSST status is 0.
The relationship between SFSOUT[3:0] outputs and the range of sampling frequency fS is shown in Table 7-8.
NOMINAL fS | ACTUAL SAMPLING FREQUENCY RANGE | CALCULATED SAMPLING FREQUENCY OUTPUT(1) | |||
---|---|---|---|---|---|
SFSOUT3 | SFSOUT2 | SFSOUT1 | SFSOUT0 | ||
Out of range | Out of range | 0 | 0 | 0 | 0 |
8 kHz | 7.84 kHz to 8.16 kHz | 0 | 0 | 0 | 1 |
11.025 kHz | 10.8045 kHz to 11.2455 kHz | 0 | 0 | 1 | 0 |
12 kHz | 11.76 kHz to 12.24 kHz | 0 | 0 | 1 | 1 |
16 kHz | 15.68 kHz to 16.32 kHz | 0 | 1 | 0 | 0 |
22.05 kHz | 21.609 kHz to 22.491 kHz | 0 | 1 | 0 | 1 |
24 kHz | 23.52 kHz to 24.48 kHz | 0 | 1 | 1 | 0 |
32 kHz | 31.36 kHz to 32.64 kHz | 0 | 1 | 1 | 1 |
44.1 kHz | 43.218 kHz to 44.982 kHz | 1 | 0 | 0 | 0 |
48 kHz | 47.04 kHz to 48.96 kHz | 1 | 0 | 0 | 1 |
64 kHz | 62.72 kHz to 65.28 kHz | 1 | 0 | 1 | 0 |
88.2 kHz | 86.436 kHz to 89.964 kHz | 1 | 0 | 1 | 1 |
96 kHz | 94.08 kHz to 97.92 kHz | 1 | 1 | 0 | 0 |
128 kHz | 125.44 kHz to 130.56 kHz | 1 | 1 | 0 | 1 |
176.4 kHz | 172.872 kHz to 179.928 kHz | 1 | 1 | 1 | 0 |
192 kHz | 188.16 kHz to 195.84 kHz | 1 | 1 | 1 | 1 |
The Biphase Sampling Frequency Calculator is also used for restricting the type of data that can be received.
Register 21h/RXFSRNG is used for global control of the acceptable sampling frequencies. If normal mode is selected, the range of acceptable sampling frequency is restricted from 28 kHz to 108 kHz. If wide mode is selected, the range is from 7 kHz to 216 kHz.