DMA Controller
8-2
Am186™CC/CH/CU Microcontrollers User’s Manual
pairs support the USB endpoints A, B, C, or D. On-chip peripherals that support general-
purpose DMA are Timer 2, the two asynchronous serial ports (the UART and the High-
Speed UART), and the USB peripheral controller. External peripherals support DMA
transfers through the external DMA request signals. Each general-purpose channel accepts
a DMA request from one of four sources: the DMA request signals (DRQ1–DRQ0), Timer
2, the UARTs, or the USB peripheral controller. (Note that Timer 2 acts only as a DMA
request source; no data is transferred to or from Timer 2.)
Up to 64 Kbytes or 64 Kwords can be transferred to or from even or odd addresses on the
Am186CC/CH/CU microcontrollers. Two bus cycles (a minimum of eight clocks) are
necessary for each general-purpose DMA data transaction. For word transfers, both the
source and destination addresses must be configured as 16-bit addresses.
The SmartDMA channels only support byte transfers. Data is written or read from sequential
byte addresses in the memory buffers. The SmartDMA channels also feature fly-by DMA
transfers—what would typically take two cycles (a read and write) is moved in a single cycle
on the external processor bus; read and write are performed concurrently in one cycle.
The general-purpose DMA channels and the SmartDMA channels can be programmed so
that one channel/channel pair is always given priority over the other, or they can be
programmed to alternate cycles when both have DMA requests pending.
Содержание Am186 CC
Страница 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Страница 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Страница 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Страница 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Страница 39: ...Architectural Overview Am186 CC CH CU Microcontrollers User s Manual 1 15 Figure 1 6 32 Channel Linecard CH CC...
Страница 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Страница 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Страница 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Страница 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Страница 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...