Samsung S5PC100, User Manual

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I2S CONTROLLER(5.1CH) S5PC100 USER’S MANUAL (REV1.0)
10.2-4
4.1.2 Internal DMA Transfer
To transfer up to 2 channel secondary sound to I2S, internal DMA or SFR interface are used. To play secondary
sound for 2 channels, internal DMA in I2S gets sound data from address range between 0xC000_0000 and
0xC01F_FFFF to TXFIFO_S if LPMP3_MODE_SEL[0] bit is high. I2S mixes 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 if TXFIFO_S is
not full. If activated, internal DMA runs according to SFR configurations and signals an interrupt after completion.
4.1.3 Sound Mixing
I2S mixes primary sound in TXFIFO0 and secondary sound in TXFIFO_S if two sound sourses have the same
sampling rate and PCM format.
+
+
I2S
Sound
Source 1
Sound
Source N - 1
Sound
Source N
Volume 1 Volume N
Master
Volume
Volume X
Master Volume
Secondary
Sound Path
Primary
Sound Path
Figure 10.2-4 Concept of Mixer in I2S
This function has two limitations:
1. Normalization should be pre-processed in S/W configurations or settings.
2. Synchronization between two sound sources is not guaranteed.