User manual
170
mikoBasic PRO for dsPIC30/33 and PIC24
MikroElektronika
DMA RAM
Every dsPIC33F device contains a portion of dual ported DMA RAM located at the end of Y data space. Direct Memory
Access (DMA) is a very efcient mechanism of copying data between peripheral SFRs and buffers or variables stored
in RAM, with minimal CPU intervention.
The DMA controller can automatically copy entire blocks of data without requiring the user software to read or write the
peripheral Special Function Registers (SFRs) every time a peripheral interrupt occurs.
The DMA controller uses a dedicated bus for data transfers and therefore, does not steal cycles from the code execution
ow of the CPU. To exploit the DMA capability, the corresponding user buffers or variables must be located in DMA
RAM.
Unimplemented Memory Space
The last segment of data RAM space is not implemented, but can be mapped into program space for Program Space
Visibility. This allows program memory to be read as though it were in data RAM.
Notes:
- Boundaries between memory spaces are device specic. Please, refer to the appropriate datasheet for details.
- Memory spaces are not shown to scale. Please, refer to the appropriate datasheet for details.
There are seven memory type speciers that can be used to refer to the data memory: rx, data, code, sfr,
xdata, ydata, and dma
Related topics: Accessing individual bits, SFRs, Memory type speciers, dsPIC Memory Type Qualiers