CS49300 Family DSP
(from the rising edge of RESET). Note: This time host had toggled the RESET line with ABOOT
has been tested using the ac3_493263_13.ld held low, only now, the code image held in the
application code release, however other application
code releases MAY take longer than 200mS as they
have may an increased image size and may take
external flash or eprom page will now be
downloaded anywhere from 1.5 to 3 times faster
than using Autoboot, depending on the gfabt code
longer to initialize all of the internal state variables. that was first downloaded.
It is up to the designer to verify the actual times
The normal DSP clock divide factor during
required for each application code in their system.
Autoboot is 12 (VCO open loop frequency
divider). The gfabt8.ld code changes that divide
factor to 8, the gfabt6.ld code changes it to 6, and
the gfabt4.ld code changes it to 4. Contact your
FAE in order to obtain these gfabt codes.
8.3. Decreasing Autoboot Times Using
GFABT Codes (Fast Autoboot)
Instead the host toggling the RESET line while
ABOOT is held low, the host decrease the
Autoboot download time by instead downloading a
special code called “GFABT” (Genesis Fast
Autoboot) which first speeds up the DSP’s core
clock, and then automatically causes the DSP to
Autoboot itself from external ROM.
Some sample data for various autoboot times can
be seen below in Table 11 using the
ac3_pl2_reeq_493264_08.ld application code. It
shows that the autoboot times after downloading
gfabt8.ld,
gfabt6.ld,
and
gfabt4.ld
are
approximately 1.5, 2, and 3 times faster than a
standard autoboot. The typical autoboot time listed
in the datasheet of 200 ms will therefore become
135 ms (200ms/1.5), 100ms (200ms/2), and 70ms
(200/3) with gfabt8, 6, and 4, respectively.
Basically, the host should perform a normal serial
host boot with one of the GFABT codes (gfabt8.ld,
gfabt6.ld or gfabt4.ld) as described in Section
8.1.1, (with ABOOT held high). Immediately
following the download of the GFABT code, the
DSP will start to act the exact same way as if the
Open Loop
VCO
Standard Autoboot Times
GFABT4.LD
GFABT6.LD
GFABT8.LD
Application
ac3_pl~1.ld
dts_6d~1.ld
eff_49~1.ld
ac3_pl~1.ld
ac3_pl~1.ld
ac3_pl~1.ld
Code Name
(8.3 File Name)
Application
Code Name
(Long File
Name)
ac3_pl2_
reeq_
493264_
08.ld
dts_6dot1_
reeq_
493264_
04.ld
eff_4932xx
_14.ld
Code Size on
Disk
94 k
94 k
47 k
12 k
Code Size in
Bytes
24 k
24 k
Sample 1
Sample 2
Sample 3
12.5 MHz
12.4 MHz
11.7 MHz
98 ms
99 ms
97 ms
96 ms
98 ms
96 ms
48 ms
50 ms
48 ms
34 ms
34 ms
32 ms
50 ms
50 ms
50 ms
65 ms
67 ms
66 ms
Table 11. Reduced Autoboot Times using GFABT8.LD, GFABT6.LD, and GFABT4.LD on a CS493264-CL Rev. G DSP
DS339PP4
59
CIRRUS [ CIRRUS LOGIC ]
