Motorola MCF5281 Capture Mode, Reference Compare, Output Mode, DMA Timer Module Memory Map

Models: MCF5282 MCF5281

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DMA Timer Programming Model

DTMRn[CLK] selects the clock input source. A programmable prescaler divides the clock input by values from 1 to 256. The prescaler output is an input to the 32-bit counter, DTCNn.

21.2.2 Capture Mode

Each DMA timer has a 32-bit timer capture register (DTCRn) that latches the counter value when the corresponding input capture edge detector senses a defined DTINn transition. The capture edge bits (DTMRn[CE]) select the type of transition that triggers the capture and sets the timer event register capture event bit, DTERn[CAP]. If DTERn[CAP] is set and DTXMRn[DMAEN] is one, a DMA request is asserted. If DTERn[CAP] is set and DTXMRn[DMAEN] is zero, an interrupt is asserted.

21.2.3 Reference Compare

Each DMA timer can be configured to count up to a reference value, at which point DTERn[REF] is set. If DTMRn[ORRI] is one and DTXMRn[DMAEN] is zero, an interrupt is asserted. If DTMRn[ORRI] is one and DTXMRn[DMAEN] is one, a DMA request is asserted. If the free run/restart bit DTMRn[FRR] is set, a new count starts. If it is clear, the timer keeps running.

21.2.4 Output Mode

When a timer reaches the reference value selected by DTRR, it can send an output signal on DTOUTn. DTOUTn can be an active-low pulse or a toggle of the current output as selected by the TMRn[OM] bit.

21.2.5 Memory Map

The timer module registers, shown in Table 21-1,can be modified at any time.

Table 21-1. DMA Timer Module Memory Map

IPSBAR

[31:24]

[23:16]

[15:8]

[7:0]

Offset

 

 

 

 

 

 

 

 

 

0x400

DMA Timer0 Mode Register (DTMR0)

DMA Timer0 Extended

DMA Timer0 Event

 

 

Mode Register (DTXMR0)

Register (DTER0)

 

 

 

 

 

 

 

 

0x404

 

DMA Timer0 Reference Register (DTRR0)

 

 

 

 

 

0x408

 

DMA Timer0 Capture Register (DTCR0)

 

 

 

 

 

0x40C

 

DMA Timer0 Counter Register (DTCN0)

 

 

 

 

 

0x440

DMA Timer1 Mode Register (DTMR1)

DMA Timer1 Extended

DMA Timer1 Event

 

 

Mode Register (DTXMR1)

Register (DTER1)

 

 

 

 

 

 

 

 

0x444

 

DMA Timer1 Reference Register (DTRR1)

 

 

 

 

 

 

MOTOROLA

Chapter 21. DMA Timers (DTIM0–DTIM3)

21-3

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Motorola MCF5281, MCF5282 user manual Capture Mode, Reference Compare, Output Mode, DMA Timer Module Memory Map