Samsung S3C2451X User Manual page 657

S3C2451X RISC MICROPROCESSOR
PROGRAMMING GUIDE
The IIS bus interface can be accessed either by the processor using programmed I/O instructions or by the DMA
controller.
INITIALIZATION
1. Before you use IIS bus interface, you have to configure GPIOs to IIS mode. And check signal's direction.
I2SLRCLK, I2SSCLK and I2SCDCLK is inout-type. The each of I2SSDI and I2SSDO is input and output.
2. Now then, you choose clock source. S3C2451 has four clock sources. Those are PCLK, divided EPLL clock
EPLLRefCLK and external codec. If you want to know more detail, refer Figure 25-2.
PLAY MODE (TX MODE) WITH DMA
1. TXFIFO is flushed before operation. If you don't distinguish Master/Slave mode from TX/RX mode, you must
study Master/Slave mode and TX/RX mode. Refer Master/Slave chapter.
2. To configure I2SMOD register and I2SPSR (IIS pre-scaler register) properly.
3. To operate system in stability, the internal TXFIFO should be almost full before transmission. First of all, DMA
starts because of that reason.
4. Basically, IIS bus doesn't support the interrupt. So, you can only check state by polling through accessing
SFR.
5. If TXFIFO is full, now then you make I2SACTIVE be asserted.
RECORDING MODE (RX MODE) WITH DMA
1. RXFIFO is flushed before operation. Also, if you don't distinguish between Master/Slave mode and TX/RX
mode, you must study Master/Slave mode and TX/RX mode. Refer Master/Slave chapter.
2. To configure I2SMOD register and I2SPSR (IIS pre-scaler register) properly.
3. To operate system in stability, the internal RXFIFO should have at least one data before DMA operation.
Because of that reason, you make I2SACTIVE be asserted.
4. Now then you check RXFIFO state by polling through accessing SFR.
5. If RXFIFO is not empty, let's start RXDMACTIVE.
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
IIS-BUS INTERFACE
25-7