Microcontroller User's Manual

21-2 MCF5282 User’s Manual MOTOROLA
DMA Timer Programming Model
Figure 21-1. DMA Timer Block Diagram
21.1.1 Key Features
Each DMA timer module has the following features:
• Maximum timeout period of 266,521 seconds at 66 MHz (~74 hours)
• 15-ns resolution at 66 MHz
• Programmable sources for the clock input, including external clock
• Programmable prescaler
• Input-capture capability with programmable trigger edge on input pin
• Programmable mode for the output pin on reference compare
• Free run and restart modes
• Programmable interrupt or DMA request on input capture or reference-compare
21.2 DMA Timer Programming Model
The following features are programmable through the timer registers, shown in Table 21-1:
21.2.1 Prescaler
The prescaler clock input is selected from system clock (divided by 1 or 16) or from the
corresponding timer input, DTINn. DTINn is synchronized to the system clock. The
synchronization delay is between two and three system clocks. The corresponding
DMA Timer
Divider
DMA Timer Mode Register (DTMRn)
Prescaler Mode Bits
DMA Timer Counter Register (DTCNn)
31 0
DMA Timer Reference Register (DTRRn)
31 0
DMA Timer Capture Register (DTCRn)
31 0
DMA Timer Event Register (DTERn)
Capture
Detection
DTINn
DTOUTn
clock
(contains incrementing value)
(reference value for comparison with DTCN)(latches DTCN value when triggered by DTINn)
(indicates capture or when DTCN = DTRRn)
IRQn
Clock
Generator
System Clock
(÷1 or ÷16
)
DMA Timer Extended Mode
Register (DTXMRn)
DREQn
0
0
15
7
7
0