DMA Controller
Am186™CC/CH/CU Microcontrollers User’s Manual
8-15
■
The DMA synchronization for the channel (“Setting Synchronization” on page 8-17)
■
Whether DMA transfers use buffer queues or circular buffers (see “Using Buffer Queues
or Circular Buffers” on page 8-20)
8.5.6.6.1
Generating Interrupts
The general-purpose DMA channels can generate an interrupt request when the terminal
count value in the GDxTC register reaches 0. To program this feature, set the INT bit in the
GDxCON0 register to 1.
8.5.6.6.2
Transferring Bytes or Words
The TS bit in the GDxCON0 register can enable either byte or word transfers.
8.5.6.6.3
Incrementing or Decrementing Addresses
The source and destination addresses can increment or decrement after each transfer, or
remain constant. Specify the action with the SINC and DINC bits in the GD
xCON1 register.
The increment or decrement factor of the source and destination addresses are
programmed independently; however, both the source and destination have to be the same
size. Word transfers are only supported when the address is incremented or decremented
by 2 (an increment by one causes unpredictable results). Byte transfers can be incremented
or decremented by 1 or 2. When a byte transfer is incremented or decremented by 2, the
high byte is ignored.
Because the DMA controller stores addresses as 20-bit linear values, there are no segment
restrictions on the address increment and decrement. However, when using the circular
buffer feature, the address boundary is limited to the size of the buffer. For example, when
using a 1-Kbyte circular buffer, the address has to start at a 1-Kbyte boundary. For more
information, see “Using Buffer Queues or Circular Buffers” on page 8-20.
8.5.6.6.4
Selecting DMA Request Sources
The DSEL bit field in the GDxCON0 register sets the DMA request source for that channel.
As shown in Figure 8-3, the DMA request source can be an external DRQ signal, Timer 2,
UART receiver, UART transmitter, High-Speed UART receiver, or High-Speed UART
transmitter.
The Am186CC and Am186CU microcontrollers also support USB endpoints A, B, C, or D
as request sources. Each USB endpoint can be configured either for receive or transmit.
In addition to setting the DMA request source, the DSEL bit field also selects the
synchronization type (see “Setting Synchronization” on page 8-17).
CU
CC
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...