Generic Channels
5-12
5.3.1.5
Autoinitialization
A DMA channel (synchronized or not) can operate in two modes.
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Single transfer mode
In this mode, a channel stops when the current transfer finishes
.
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Autoinitialization mode
In this mode, a channel loads a new configuration and automatically
restarts a new transfer when the current one finishes.
A DMA channel has two sets of configuration registers: programming and
active. Only the programming set is accessible through the TIPB. When a
channel is enabled for the first time or when a channel autoinitializes, the
programming set is copied in the active set of registers. You can then pro-
gram the programming set to configure the next transfer while the current
transfer is running.
This feature can be used in two ways:
J
Continuous operation
You can change the programming registers while the current configu-
ration is executed. The next transfer is transferred with a new context
but without stopping the DMA.
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Repetitive operation
You never modify the programming registers. The same context is
always used.
The programming set includes the following registers:
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DMA_CSSA_L
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DMA_CSSA_U
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DMA_CDSA_L
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DMA_CDSA_U
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DMA_CEN
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DMA_CFN
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DMA_CFI
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DMA_CEI
The following registers are part of the working set and are accessible. They
always have impact on the current transfer.
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DMA_CSDP
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DMA_CCR
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DMA_CICR
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DMA_CSR