Analog Devices VISUALDSP++ 3.5, Руководство пользователя

Страница: 135 / 166

Vi+ 3.5 Loader Manual 5-11
for 16-Bit Processors
ADSP-218x DSP Loader/Splitter
Host Booting (IDMA)
When booted through the IDMA interface, an ADSP-218x DSP behaves
like a slave. After reset, it does not start program execution until internal
PM location
0x0000
is overwritten by an IDMA write access. The host
processor initializes all on-chip memories of the DSP but finally writes to
PM address
0x0000
. Then the DSP starts program execution.
The host is responsible for handling the IDMA traffic properly. Typically,
the host boots the DSP page-by-page (segment-by-segment). To boot a
segment, the host first performs an address latch cycle to program the
IDMA Control register and the IDMA Overlay register (on ADSP-2184
through ADSP-2189 DSPs only). Afterwards, the host writes 16- or 24-bit
words to the IDMA port. The DSP auto-increments its address counter.
Figure 5-1 on page 5-12 illustrates the algorithm the host processor must
compute to boot the DSP successfully.
-uload filename
Reads the BDMA preloader from
filename.doj
.
The preloader must consist of exactly 32 instructions. Preloaders gener-
ated by the
elfspl21
utility automatically determine the
BWCOUNT
value, which mirrors the numbers of instructions required by the page
loaders. Customized preloaders do not have access to this length infor-
mation and should always set
BWCOUNT
by assuming the maximal possi-
ble page loader length.
In this software version, the maximal number of instructions required
for the page loader is 658. This may change in future releases.
-offsetaddr #
Provides byte memory address offset (valid only with
-2181 -noloader
or with
-218x -noloader
).
-offsetpage #
Provides byte memory page offset (valid only with
-2181 -noloader
or with
-218x -noloader
).
Table 5-5. ADSP-218x DSP: BDMA Mode Command-Line Switches
Switch Description