User's Manual

PCM AUDIO INTERFACE S3C2450X RISC MICROPROCESSOR
28-6
3.4 PCM CONTROL REGISTER
The PCM_CTL register is used to control the various aspects of the PCM module. It also provides a status bit to
provide the option to using polling instead of interrupt based control.
Register Address R/W Description Reset Value
PCM_CTL0 0x5C000000 R/W Control the PCM0 Audio Interface 0x00000000
PCM_CTL1 0x5C000100 R/W Control the PCM1 Audio Interface 0x00000000
The bit definitions for the PCM_CTL Control Register are shown below:
PCM_CTLn Bit Description Initial State
Reserved [31:19] Reserved
TXFIFO_DIPSTICK [18:13] Determines when the almost_full, almost_empty flags go
active for the TXFIFO
TXFIFO_ALMOST_EMPTY: txfifo_depth < txfifo_dipstick
TXFIFO_ALMOST_FULL: txfifo_depth > (32 –
txfifo_dipstick)
Note:
- If txfifo_dipstick is 0, Almost_empty, Almost_full are invalid
- For DMA loading of TX fifo, Txfifo_dipstick should be equal to 2
or greater than 2(txfifo_dipstick >= 2)
This is required since the PCM_TXDMA uses
TXFIFO_ALMOST_FULL as the DMA request (keep requesting data
until the FIFO is almost full) In some circumstances, the DMA write
one more word after the DMA_req goes away. Thus the almost_full
flag most go active with at least space for one extra word in the fifo
0
RXFIFO_DIPSTICK [12:7] Determines when the almost_full, almost_empty flags go
active for the RXFIFO
RXFIFO_ALMOST_EMPTY : fifo_depth < fifo_dipstick
RXFIFO_ALMOST_FULL : fifo_depth > (32 – fifo_dipstick)
Note:
- If fifo_dipstick is 0, Almost_empty, Almost_full are invalid.
- For DMA, RXFIFO_DIPSTICK is a don’t care.
(DMA unloading of RX fifo uses the RXFIFO_EMPTY flag as the
DMA request)
- Non-DMA IRQ/polling RXFIFO_DIPSTICK should be 32.
This will have the effect of RXFIFO_ALMOST_FULL acting as a
rx_fifo_not_empty flag (as a not RXFIFO_EMPTY).
0
PCM_TX_DMA_EN [6] Enable the DMA interface for the TXFIFO DMA must operate
in the demand mode.
DMA_TX request will occur whenever the TXFIFO is not
almost full
0
PCM_RX_DMA_EN [5] Enable the DMA interface for the RXFIFO DMA must operate
in the demand mode.
0