ADSP-214xx SHARC Processor Hardware Reference 4-17
Link Ports—ADSP-2146x
Interrupt Sources
Five types of interrupts are dedicated to link ports.
1. A DMA channel interrupt is generated when a DMA block transfer
through the link port with DMA enabled completes.
2. A DMA channel interrupt is generated when DMA for the link
buffer channel is disabled and the buffer is not full or the buffer is
not empty.
3. A link service request interrupt is generated when an external
source accesses the link port when the link port is disabled. (LxTRQ
and LxRRQ). For example, if the enabled receiver wants to initiate a
data transfer with the disabled transmitter, it can make LACKx high.
When LACKx of the disabled link port goes high, then a link service
request interrupt is generated. Now the receiver can initiate the
transfer.
4. A link port invalid transmit LPIT is generated if the transmitter is
driving LCLKx high because the receiver has not asserted LACKx and
LCLKx goes low due to a processor reset (or some other reason, even
though the receiver has not yet asserted LACKx). In this case, the
receiving link port generates an interrupt.
5. The transmitter generates an external transfer done interrupt once
the external transfer is completed. When DMA is not enabled, this
interrupt is generated when the transmitter FIFO is empty and the
last byte has been transmitted. If using DMA, the transmitter
checks if the DMA is complete.
Interrupt Service
All interrupts are latched and stored in the corresponding status register.
Whenever any of these four interrupts occur, the corresponding interrupt
LP0I or LP1I occurs if it is unmasked. In the ISR, the user should read the
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