The dst argument supplies the peripheral or memory address to which the transfer will write. Since the callback function is executed as a DSR, only a subset of eCos operations are valid. The count argument is a count of the number of data items that remain to be transferred, and will be zero for a successful transfer. The polled argument configures the stream for polled mode if true, otherwise it will be interrupt driven. The following are examples of how definitions can be made:
|Date Added:||16 July 2012|
|File Size:||40.67 Mb|
|Operating Systems:||Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X|
|Price:||Free* [*Free Regsitration Required]|
The DMA controller hardware when using double buffer mode will automatically switch buffers on a buffer fill event.
Atmel DMAC Driver
For configurations where Descriptor Integrity Check support is available, and enabled, then if an error is detected in a referenced memory-based transfer structure this result will be raised. Calling the function with enable set to false will disable the double buffer mode, with the passed memory1 parameter being ignored.
Ecow normal callback handler is subsequently called with a non-zero count indicating a partial transfer. The user is directed towards the relevant Atmel documentation for a full description of the DMAC devices, and to the variant device drivers for examples of the use of this API.
The priv argument is a client specified value that will be passed to the callback function, and can be used to reference client driver specific data.
Re: RedBoot ROM monitor causes DMA errors!!
Once this function call completes the channel is operational and will transfer data once the relevant peripheral starts triggering transfers. A DMAC instance is defined by a controller number 0 or 1and each controller has support for a dmq of variant defined channels. The prototype of the callback is as follows:. This documentation only gives a brief description of the functions available. The count argument is the number of data items successfully transferred.
The ch argument describes the DMA channel, with the descriptor used when allocating the channel defining how the other arguments are used. The priority argument defines both the interrupt level assigned to the stream interrupt, and the DMA channel arbitration priority level defined by the top two bits.
When using dmaa buffer mode the developer should ensure that the buffer size used is large enough to cope with the processing code associated with a completed transaction being able to complete to avoid overrun.
The data argument is a copy of the data field from the stream structure. A valid transfer completion. If the stream is configured for interrupt control then when a transfer completes an interrupt is raised. This documentation only gives a brief description of the functions available.
Jürgen Lambrecht – Re: RedBoot ROM monitor causes DMA errors!!
This will disable the stream and cause the callback in the stream structure to be called from DSR mode. The polled argument configures the stream for polled mode if true, otherwise it will be interrupt driven.
Also, depending on the descriptor construction macros used, it is possible to eecos the direction and modification of addresses during transfers. It is currently limited to single DMA transfers.
When the transfer has completed the callback function will be called from within the poll routine. The data argument is the client private data registered for the callback. Most drivers will allocate a DMA channel object and keep it active throughout the system lifetime. The driver needs to detect this and terminate the polling loop. It is mainly limited to supporting peripheral DMA e.
The extended descriptor allows for non-default FIFO configurations and transfer chunk sizes to be specified. Once this call completes, the channel is operational and will transfer data once the peripheral starts triggering transfers.
This support is not intended to expose the full functionality of dam devices. The cbid argument is a completion identifier:.
The register callback function has the following prototype: The API uses a simple bit encoding to describe how a specific DMA channel should be used, with this package providing helper macros to combine the necessary information into a unique descriptor.
The size of the buffers will eco on the DMA transfer rate for the peripheral being used and the application DSR latency, plus the actual callback buffer processing code time. This allows circular buffers and continuous data flows e. When appropriate the stream will be disabled by the DMA controller and the relevant callback handler function called asynchronously.
Calling the function with enable set to false will disable circular mode.