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Сигнальный МП Motorola DSP56002.pdf
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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

HOST INTERFACE (HI)

XFEREQ

 

 

 

 

 

HREQ

DMA

 

 

 

 

 

DSP560021

CONTROLLER

 

 

 

 

 

 

XFERACK

 

 

 

 

 

HACK

24-BIT TRANSFER

H

M

L

H

M

L

(INTERNAL COUNTER)

(01)

(10)

(11)

(01)

(10)

(11)

16-BIT TRANSFER

M

L

M

L

M

L

(INTERNAL COUNTER)

(10)

(11)

(10)

(11)

(10)

(11)

 

 

 

 

 

HOST

 

 

 

 

 

 

 

 

 

 

 

 

RECEIVE

 

 

 

 

 

 

INTERRUPT

8-BIT TRANSFER

L

L

L

L

L

L

(INTERNAL COUNTER)

(11)

(11)

(11)

(11)

(11)

(11)

 

 

 

 

 

 

 

FAST INTERRUPT ROUTINE

 

 

 

 

 

P:$0020 MOVE X:$FFE8,A

 

READ HRX

 

 

 

P:$0021 MOVE A, Y:(R7)+

 

;AND PUT INTO Y MEMORY

 

Figure 5-37 DMA Transfer and Host Interrupts

5.3.6.3.1Host To DSP Internal Processing

The following procedure outlines the steps that the HI hardware takes to transfer DMA data from the host data bus to DSP memory (see Figure 5-36 and Figure 5-37).

1.HI asserts the HREQ pin when TXDE=1.

2.DMA controller enables data on H0-H7 and asserts HACK.

3.When HACK is asserted, the HI deasserts HREQ.

4.When the DMA controller deasserts HACK, the data on H0-H7 is latched into the TXH, TXM, TXL registers.

5.If the byte register written was not TXL (i.e., not $7) the DMA address counter internal to the HI increments and HREQ is again asserted. Steps 2-5 are then repeated.

6.If TXL ($7) was written, TXDE will be set to zero and the address counter in the HI will be loaded with the contents of HM1 and HM0. When TXDE=0, the contents of TXH:TXM:TXL are transferred to HRX provided HRDF=0. After the transfer to HRX, TXDE will be set to one, and HREQ will be asserted to start the transfer of another word from external memory to the HI.

7.When the transfer to HRX occurs within the HI, HRDF is set to one. Assuming HRIE=1, a host receive exception will be generated. The exception routine

must read the HRX to clear HRDF.

Note: The transfer of data from the TXH, TXM, TXL registers to the HRX register auto-

MOTOROLA PORT B 5 - 57

For More Information On This Product, Go to: www.freescale.com

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