Module Operation
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SPNU563A–March 2018
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Direct Memory Access Controller (DMA) Module
20.2.10 Debugging
The DMA supports four different behaviors in suspend mode. These behaviors can be configured by the
user as per the application requirement.
• Immediate stop at a DMA channel arbitration boundary. Please refer to Table 20-4 and Table 20-5 for
arbitration boundary definition.
• Finish current frame transfer and continue after suspend ends.
• Finish current block transfer and continue after suspend ends.
• Ignore the suspend. The DMA continues to be operational as in functional mode when debug mode is
active.
When the DMA controller enters suspend mode, it continues to sample incoming hardware DMA requests,
but the Channel Pending Register (Section 20.3.1.2) is frozen from being updated. After the suspend
ends, all new requests that were received during suspend mode are reflected in the Channel Pending
Register (Section 20.3.1.2).
Except when the DMA controller is configured to ignore suspend mode, no channel arbitration is
performed during suspend mode. The current channel under which suspend mode was entered will finish
its entire frame or block-transfer after suspend mode ends, depending how the debug option was chosen.
To facilitate debugging, a Watch Point Register (Section 20.3.1.54) and a Watch Mask Register
(Section 20.3.1.55) are used. The watch point register together with the watch mask register can be
configured to watch for a unique address or a range of addresses. When the condition to watch is true, the
DMA freezes its state and generates a debug request signal to the host CPU so the state of the DMA can
be examined.
20.2.11 Power Management
The DMA offers two power-management modes: run and sleep. In run mode, the DMA is fully operational.
The sleep mode shuts down the DMA if no pending channels are waiting to be serviced. If a DMA request
is received or a software request is generated by the user software, then the DMA wakes up immediately.
The sleep mode may be used to optimize the DMA module power consumption.
When the system module issues a global low power mode request, the DMA will respond to the system
module with an acknowledge as soon as an arbitration boundary is reached. If no DMA requests are
pending, it will respond with an acknowledge immediately.
NOTE: When the DMA is in global low power mode, the clock is stopped and therefore it cannot
detect any DMA request. The device must be woken up before a peripheral can generate a
DMA request.
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