Samsung S5PC110 Manual page 1823

S5PC110_UM
2.4.1.1 External DMA Transfer
To transfer up to 5.1 channel primary sound from s/w mixer to IIS, use external DMA or SFR interface. To play
primary sound for 5.1 channels or record 2 channel sound, IIS has TXFIFO0, TXFIFO1, TXFIFO2, TXFIFO_S and
RXFIFO registers. IIS will mix primary sound in TXFIFO0 and secondary sound in TXFIFO_S and output mixed
sound stream to external codec logic.
In the external DMA transfer mode, use external DMA controller to access the transmitter or receiver FIFO. The
transmitter or receiver FIFO state activates DMA service request internally. The FTXEMPT, FRXEMPT, FTXFULL,
and FRXFULL bits of I2SCON register represent the transmitter or receiver FIFO data state. Especially,
FTXEMPT and FRXFULL bit are the ready flag for DMA service request; the transmit DMA service request is
activated when TXFIFO is not empty and the receiver DMA service request is activated when RXFIFO is not full.
The external DMA transfer uses only handshaking method for single data. Note that during external DMA
acknowledge activation; the data read or write operation should be performed.
* Reference: DMA request point
• TX mode: (FIFO is not full) & (TXDMACTIVE is active)
• RX mode: (FIFO is not empty) & (RXDMACTIVE is active)
2.4.1.2 Internal DMA Transfer
To transfer up to 2 channel secondary sound to IIS, use internal DMA or SFR interface. To play secondary sound
for 2 channels, internal DMA in IIS gets sound data from address range between 0xC000_0000 and
0xC01F_FFFF (when ARM decodes encoded music file.) or between OBUF0 and OBUF1 (when RP decodes
encoded music file.) to TXFIFO_S. IIS will mix primary sound in TXFIFO0 and secondary sound in TXFIFO_S and
output mixed sound stream to external codec logic.
Like external DMA transfer mode, in the internal DMA transfer mode, the internal DMA is activated when
TXFIFO_S is not full. After activation, internal DMA runs according to SFR configurations and signals an interrupt
after completion.
• It only supports single transfer in both Internal & External DMA transfer mode.
• Refer OBUF0 and OBUF1 at 10.01.S5PC110_Low Power Audio Subsystem chapter.
2.4.1.3 Sound Mixing
IIS can mix primary sound in TXFIFO0 and secondary sound in TXFIFO_S when two sound sources have the
same sampling rate and PCM format.
If overflow occurs, then mixer saturates output value.
•
• Mixer can handle Different Bit Length. (Controlled by BLC bit at IISMOD SFR)
2 IIS MULTI AUDIO INTERFACE
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