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VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

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ADSP-21161 Processor Booting<br />

After the boot process loads 256 words into memory locations 0x40000<br />

through 0x400FF, the processor begins executing instructions. Because<br />

most processor programs require more than 256 words of instructions <strong>and</strong><br />

initialization data, the 256 words typically serve as a loading routine for<br />

the application. <strong>VisualDSP++</strong> includes loading routines (boot kernels)<br />

that can load entire programs; refer to “ADSP-21161 Processor Boot Kernels”<br />

on page 4-16 for more information.<br />

Refer to the ADSP-21161 SHARC DSP Hardware Reference for detailed<br />

information on DMA <strong>and</strong> system configurations.<br />

� DMA<br />

channel differences between ADSP-21161 <strong>and</strong> previous<br />

SHARC family processors (ADSP-2106x) account for boot differences.<br />

Even with these differences, ADSP-21161 processors<br />

support the same boot capability <strong>and</strong> configuration as<br />

ADSP-2106x processors. The DMAC10 register default values differ<br />

because the ADSP-21161processor has additional parameters <strong>and</strong><br />

different DMA channel assignments. Host boot mode uses EPB0,<br />

DMA channel 10.<br />

The processor determines the boot mode at reset from the EBOOT, LBOOT,<br />

<strong>and</strong> BMS pin inputs. When EBOOT=0, LBOOT=0, <strong>and</strong> BMS=1, the processor<br />

boots from a host through the external port. Refer to Table 4-1 <strong>and</strong><br />

Table 4-2 on page 4-4 for boot mode selection.<br />

When using any of the power-up boot modes, address 0x40004 should not<br />

contain a valid instruction. Because it is not executed during the boot<br />

sequence, place a NOP or IDLE instruction at this location.<br />

During reset, the processor ACK line is internally pulled high with an<br />

equivalent 20K ohm resistor <strong>and</strong> is held high with an internal keeper<br />

latch. It is not necessary to use an external pull-up resistor on the ACK line<br />

during booting or at any other time.<br />

4-10 <strong>VisualDSP++</strong> <strong>4.5</strong> <strong>Loader</strong> <strong>and</strong> <strong>Utilities</strong> <strong>Manual</strong>

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