ADSP-214xx SHARC Processor Hardware Reference 8-17
Media Local Bus
7. Configure the logical channel using the
MLB_CECRx register for I/O
mode, transfer direction, channel type, channel address and inter-
rupt generation.
For a transmit, a transmit service request, (STS bit 1 in the
MLB_CSCRx register) an interrupt is generated when the local chan-
nel buffer can accept data. Within the ISR, check if this status bit is
set. If set, write the data into transmit data buffer (MLB_CNBCRx).
For a receive, a receive service request, (STS bit 2 in the MLB_CSCRx
register) an interrupt is generated when the local channel buffer has
data to be read. Within the ISR, check if this status bit is set. If set,
read the data from the receive data buffer (MLB_CCBCRx).
8. Clear all interrupts by writing 0x0000FFFF to the MLB_CSCRx
register.
DMA Modes
MLB channels can be configured for circular buffer DMA mode by pro-
gramming the channel mode select bits (MLB_CECRx register, bits 25–26 =
01) for synchronous channels only. In contrast to DMA mode with
ping-pong buffering, circular buffering uses a single, circular memory buf-
fer to process channel data.
To configure a ping-pong or circular buffered DMA, use the following
procedure.
1. Reset the MLB device.
2. Program the appropriate bits in the PICRx register to generate MLB
interrupt.
3. Unmask the appropriate bits in the
MLB_SSCR register inorder to
monitor the MLB network.
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