ADSP-2186L1111 Ver la hoja de datos (PDF) - Analog Devices
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ADSP-2186L1111 Datasheet PDF : 36 Pages
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ADSP-2186L
Table VI. Boot Summary Table
Mode C
0
Mode B
0
Mode A
0
Booting Method
BDMA feature is used to load
the first 32 program memory
words from the byte memory
space. Program execution is
held off until all 32 words
have been loaded. Chip is
configured in Full Memory
Mode.
0
1
0
No Automatic boot opera-
tions occur. Program execu-
tion starts at external memory
location 0. Chip is config-
ured in Full Memory Mode.
BDMA can still be used but
the processor does not auto-
matically use or wait for these
operations.
1
0
0
BDMA feature is used to load
the first 32 program memory
words from the byte memory
space. Program execution is
held off until all 32 words
have been loaded. Chip is
configured in Host Mode.
Additional interface hardware
is required.
1
0
1
IDMA feature is used to
load any internal memory as
desired. Program execution is
held off until internal program
memory location 0 is written
to. Chip is configured in
Host Mode.
IDMA Booting
The ADSP-2186L can also boot programs through its Internal
DMA port. If Mode C = 1, Mode B = 0, and Mode A = 1, the
ADSP-2186L boots from the IDMA port. The IDMA feature
can load as much on-chip memory as desired. Program execu-
tion is held off until on-chip program memory location 0 is
written to.
Bus Request and Bus Grant
The ADSP-2186L can relinquish control of the data and address
buses to an external device. When the external device requires
access to memory, it asserts the bus request (BR) signal. If the
ADSP-2186L is not performing an external memory access, it
responds to the active BR input in the following processor cycle by:
• Three-stating the data and address buses and the PMS, DMS,
BMS, CMS, IOMS, RD, WR output drivers,
• Asserting the bus grant (BG) signal, and
• Halting program execution.
If Go Mode is enabled, the ADSP-2186L will not halt program
execution until it encounters an instruction that requires an
external memory access.
If the ADSP-2186L is performing an external memory access
when the external device asserts the BR signal, it will not three-
state the memory interfaces or assert the BG signal until the
processor cycle after the access completes. The instruction does
not need to be completed when the bus is granted. If a single
instruction requires two external memory accesses, the bus will
be granted between the two accesses.
When the BR signal is released, the processor releases the BG
signal, reenables the output drivers and continues program
execution from the point at which it stopped.
The bus request feature operates at all times, including when
the processor is booting and when RESET is active.
The BGH pin is asserted when the ADSP-2186L is ready to
execute an instruction but is stopped because the external bus is
already granted to another device. The other device can release
the bus by deasserting bus request. Once the bus is released, the
ADSP-2186L deasserts BG and BGH and executes the external
memory access.
Flag I/O Pins
The ADSP-2186L has eight general purpose programmable input/
output flag pins. They are controlled by two memory mapped
registers. The PFTYPE register determines the direction,
1 = output and 0 = input. The PFDATA register is used to read
and write the values on the pins. Data being read from a pin
configured as an input is synchronized to the ADSP-2186L’s
clock. Bits that are programmed as outputs will read the value
being output. The PF pins default to input during reset.
In addition to the programmable flags, the ADSP-2186L has
five fixed-mode flags, FI, FO, FL0, FL1, and FL2. FL0-FL2
are dedicated output flags. FI and FO are available as an
alternate configuration of SPORT1.
Note: Pins PF0, PF1 and PF2 are also used for device configu-
ration during reset.
BIASED ROUNDING
A mode is available on the ADSP-2186 or ADSP-2186L to allow
biased rounding in addition to the normal unbiased rounding.
When the BIASRND bit is set to 0, the normal unbiased round-
ing operations occur. When the BIASRND bit is set to 1, biased
rounding occurs instead of the normal unbiased rounding. When
operating in biased rounding mode all rounding operations with
MR0 set to 0x8000 will round up, rather than only rounding up
odd MR1 values.
For example:
Table VII. Biased Rounding Example
MR Value
Before RND
00-0000-8000
00-0001-8000
00-0000-8001
00-0001-8001
00-0000-7FFF
00-0001-7FFF
Biased
RND Result
00-0001-8000
00-0002-8000
00-0001-8001
00-0002-8001
00-0000-7FFF
00-0001-7FFF
Unbiased
RND Result
00-0000-8000
00-0002-8000
00-0001-8001
00-0002-8001
00-0000-7FFF
00-0001-7FFF
REV. B
–11–
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