Analog Devices ee-03 Application Notes

Engineer To Engineer Note EE-3

Notes on using Analog Devices’ DSP, audio, & video components from the Computer Products Division

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Writing to Flash Memory on the
ADSP-2106x

Last Modified: 10/24/96

Introduction

This note explains how to write to ADSP-2106x
(SHARC) BMS space using the boot select override (BSO
mode). The explanation includes a general description of
BSO operations and a source code example for writing to
flash memory or EEPROM.

The BSO (Boot Select Override) mode bit in the
SYSCON register allows the BMS pin to be asserted

under software control. In PROM boot mode, an initial
256-word boot-kernel is automatically read from an 8-bit
wide PROM. This kernel can set the BSO bit to let the
DSP read the remaining application code from the
PROM. In many systems, the boot data may need to be
updated or modified. In these cases, the PROM may be
substituted by a write-able EEPROM or FLASH memory.
The code example demonstrates how to write to the same
memory space, selected by the BMS pin, that the

SHARC reads from in PROM boot mode.

When BSO is set, DMA channels 7-9 can be used with
any of the modes available in the DMACx register (for
read or write), any packing mode, and any data or
instruction.

BSO Write Code Example

The following code example uses DMA channel 7 to write
to an 8-bit wide memory connected to pins DATA23-16
of the EP bus. The connections between the SHARC and
flash memory appear in Figure 1. Following the code
example, an architecture file for a corresponding SHARC­flash-memory system appears.

DATA 47-0

FLASH

DMA READ

FLASH DMA

WRITE

Figure 1 - SHARC-To-Flash-Memory Connections

078151623243132394047

Notes on BSO operation

When BSO is set, the BMS pin will assert only on an
External Port (EP) DMA read or write. BMS does not
assert on a DSP core access of the EP.

When BSO is set, an EP DMA does not assert the MS1x
pins. DSP core accesses are not affected by BSO.

To write to memory with the BMS asserted, use DMA
channels 7, 8 or 9. DMA channel 6 should only be used

for a read when BSO is set. This limitation of accesses
appears because DMA channel 6 is hardwired for a special
8-bit boot read mode

When BSO is set, a write with DMA channel 6 with BSO
set results in illegal chip operation.

/*________________________________________

BSOWRITE.ASM
ADSP-21060 Flash Write Transfer Example

________________________________________*/

/* define number of 48-bit words
to write to FLASH */

#define N 8
#include "def21060.h"
.SEGMENT/DM dm32_b1;
.VAR temp;
.ENDSEG;
.SEGMENT/DM extdata;

/* Location of FLASH memory */
.VAR flash[N*6];
.ENDSEG;

/* interrupt vector table */
.SEGMENT/PM pm48_1b0;
resoi: nop;nop;nop;nop;

reset: nop;nop;nop;jump start;
res1i: nop;nop;nop;rti;

sovfi: nop;nop;nop;rti;

/* status stack ovflw, PC stack full */

tmzhi: nop;nop;nop;rti;

/* timer high priority */

virpt: nop;nop;nop;rti;

/* vector interrupt */

irq2i: nop;nop;nop;rti;

/* irq2 asserted */

irq1i: nop;nop;nop;rti;

/* irq1 asserted */

irq0i: nop;nop;nop;rti;

/* irq0 asserted */

res2i: nop;nop;nop;rti;

spr0i: nop;nop;nop;rti;

/* sport0 receive DMA */

spr1i:lp0i: nop;nop;nop;rti;

/* sport1 receive or link port 0 DMA */

spt0i: nop;nop;nop;rti;

/* sport0 transmit or link port 0 DMA*/

spt1i:lp1i: nop;nop;nop;rti;

/* sport1 transmit DMA */

lp2i: nop;nop;nop;rti;

/* link port 2 DMA */

lp3i: nop;nop;nop;rti;

/* link port 3 DMA */

ep0i:lp4i: nop;nop;nop;rti;

/* reserved */

/* reserved */

/* reserved */

/* ext port 0 or link port 4 DMA */

ep1i:lp5i: nop;nop;nop;rti;

/* ext port 1 or link port 5 DMA */

ep2i: nop;nop;nop;rti;

/* ext port 2 DMA */

ep3i: nop;nop;nop;rti;

/* ext port 3 DMA */

.VAR source[N];

/* block of 48-bit wide test data */

/*_______ start of main routine ________*/

start:
ustat1=0x00108421;
dm(WAIT)=ustat1;

/* No waistates enabled in example */

px1=0x2211;

/* Fill source with test data */
px2=0x66554433;
i8=source;
l8=0;
m8=1;
lcntr=@source;
do fill_tst until lce;
fill_tst: pm(i8,m8)=px;

call write_block; /* Write out source */

stop: jump stop;

/* --------------------------------------­Write block of 48-bit words to 8-bit wide

memory with BMS pin asserted

---------------------------------------- */
write_block:
i8=source;

EE-3 Page 2

Notes on using Analog Devices’ DSP, audio, & video components from the Computer Products Division

Phone: (800) ANALOG-D or [phone], FAX: [phone], EMAIL: [e-mail]