Renesas SH7781 - Manual (Page 1358)

26. Serial Sound Interface (SSI) Module
Rev.1.00 Jan. 10, 2008 Page 1328 of 1658
REJ09B0261-0100
26.4.5 Transmit Operation
Transmission can be controlled in one of two ways: either DMA or an interrupt driven.
DMA driven is preferred to reduce the CPU load. In DMA control mode, an underflow or
overflow of data or DMAC transfer end is notified by using an interrupt.
The alternative is using the interrupts that the SSI module generates to supply data as required.
This mode has a higher interrupt load as the SSI module is only double buffered and will require
data to be written at least every system word period.
When disabling the SSI module, the SSI clock* must be supplied continuously until the module
enters in the idle state, indicated by the IIRQ bit.
Figure 26.21 shows the transmit operation in the DMA controller mode. Figure 26.22 shows the
transmit operation in the interrupt controller mode.
Note: * SCKD = 0: Clock input through the SSI_SCK pin
SCKD = 1: Clock input through the SSI_CLK pin