DSP56366 datasheet(23/25 Pages) MOTOROLA

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Chip Errata

DSP56366 Digital Signal Processor

Mask:2J26D

DSP56366 Errata

366CE2J26D_0_0

NG 11/12/01 pg. 23 of 25

 1997 -2001, Motorola

ED40

Description (added 11/11/99):

When an instruction with all the following conditions follows a repeat

instruction, then the last move will be corrupted.:

1. The repeated instruction is from external memory.

2. The repeated instruction is a DALU instruction that includes 2 DAL

registers, one as a source, and one as destination (e.g. tfr, add).

3. The repeated instruction has a double move in parallel to the DALU

instruction: one move’s source is the destination of the DALU instruction

(causing a DALU interlock); the other move’s destination is the source of

the DALU instruction.

Example:

rep #number

tfr x0,a

x(r0)+,x0

a,y0 ; This instruction is from external memory

|__|_________|------|----------> This is condition 3 second part.

|_____________|----------> This is condition 3, first part - DALU interlock

In this example, the second iteration before the last, the "x(r0)+,x0" doesn’t

happen. On the first iteration before the last, the X0 register is fixed with

the "x(r0)+,x0", but the "tfr x0,a" gets the wrong value from the previous

iteration’s X0. Thus, at the last iteration the A register is fixed with "tfr

x0,a", but the "a,y0" transfers the wrong value from the previous iteration’s

A register to Y0.

Workaround:

1. Use the DO instruction instead; mask any necessary interrupts before the

DO.

2. Run the REP instructions from internal memory.

3. Don’t make DALU interlocks in the repeated instruction. After the

repeat make the move. In the example above, all the "move a,y0" are

redundant so it can be done in the next instruction:

rep #number

tfr x0,a

x(r0)+,x0

move a,y0

If no interrupts before the move is a must, mask the interrupts before the

REP. Pertains to: DSP56300 Family Manual, Rev. 2, Section A.3,

“Instruction Sequence Restrictions.”

2J26D

Errata Description

Applies

to Mask

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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