ADSP-21xx
REV.
–13–
If the ADSP-21xx 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
cycle after the access completes (up to eight cycles later depend-
ing on the number of wait states). The instruction does not need
to be completed when the bus is granted; the ADSP-21xx will
grant the bus in between two memory accesses if an instruction
requires more than one external memory access.
When the
BR signal is released, the processor releases the BG
signal, re-enables the output drivers and continues program
execution from the point where it stopped.
The bus request feature operates at all times, including when
the processor is booting and when
RESET is active. If this
feature is not used, the
BR input should be tied high (to V
DD
).
Low Power IDLE Instruction
The IDLE instruction places the ADSP-21xx processor in low
power state in which it waits for an interrupt. When an interrupt
occurs, it is serviced and execution continues with instruction
following IDLE. Typically this next instruction will be a JUMP
back to the IDLE instruction. This implements a low-power
standby loop.
The IDLE n instruction is a special version of IDLE that slows
the processor’s internal clock signal to further reduce power
consumption. The reduced clock frequency, a programmable
fraction of the normal clock rate, is specified by a selectable
divisor, n, given in the IDLE instruction. The syntax of the
instruction is:
IDLE n;
where n = 16, 32, 64, or 128.
The instruction leaves the chip in an idle state, operating at the
slower rate. While it is in this state, the processor’s other
internal clock signals, such as SCLK, CLKOUT, and the timer
clock, are reduced by the same ratio. Upon receipt of an
enabled interrupt, the processor will stay in the IDLE state for
up to a maximum of n CLKIN cycles, where n is the divisor
specified in the instruction, before resuming normal operation.
When the IDLE n instruction is used, it slows the processor’s
internal clock and thus its response time to incoming interrupts–
the 1-cycle response time of the standard IDLE state is in-
creased by n, the clock divisor. When an enabled interrupt is
received, the ADSP-21xx will remain in the IDLE state for up
to a maximum of n CLKIN cycles (where n = 16, 32, 64, or
128) before resuming normal operation.
When the IDLE n instruction is used in systems that have an
externally generated serial clock (SCLK), the serial clock rate
may be faster than the processor’s reduced internal clock rate.
Under these conditions, interrupts must not be generated at a
faster rate than can be serviced, due to the additional time the
processor takes to come out of the IDLE state (a maximum of n
CLKIN cycles).
ADSP-216x Prototyping
You can prototype your ADSP-216x system with either the
ADSP-2101 or ADSP-2103 RAM-based processors. When code
is fully developed and debugged, it can be submitted to Analog
Devices for conversion into a ADSP-216x ROM product.
The ADSP-2101 EZ-ICE emulator can be used for develop-
ment of ADSP-216x systems. For the 3.3 V ADSP-2162 and
ADSP-2164, a voltage converter interface board provides 3.3 V
emulation.
Additional overlay memory is used for emulation of ADSP-
2161/62 systems. It should be noted that due to the use of off-
chip overlay memory to emulate the ADSP-2161/62, a perfor-
mance loss may be experienced when both executing instruc-
tions and fetching program memory data from the off-chip
overlay memory in the same cycle. This can be overcome by
locating program memory data in on-chip memory.
Ordering Procedure for ADSP-216x ROM Processors
To place an order for a custom ROM-coded ADSP-2161,
ADSP-2162, ADSP-2163, or ADSP-2164 processor, you must:
1. Complete the following forms contained in the ADSP ROM
Ordering Package, available from your Analog Devices sales
representative:
ADSP-216x ROM Specification Form
ROM Release Agreement
ROM NRE Agreement & Minimum Quantity Order (MQO)
Acceptance Agreement for Pre-Production ROM Products
2. Return the forms to Analog Devices along with two copies of
the Memory Image File (.EXE file) of your ROM code. The
files must be supplied on two 3.5" or 5.25" floppy disks for
the IBM PC (DOS 2.01 or higher).
3. Place a purchase order with Analog Devices for non-recurring
engineering changes (NRE) associated with ROM product
development.
After this information is received, it is entered into Analog
Devices’ ROM Manager System which assigns a custom ROM
model number to the product. This model number will be
branded on all prototype and production units manufactured to
these specifications.
To minimize the risk of code being altered during this process,
Analog Devices verifies that the .EXE files on both floppy disks
are identical, and recalculates the checksums for the .EXE file
entered into the ROM Manager System. The checksum data, in
the form of a ROM Memory Map, a hard copy of the .EXE file,
and a ROM Data Verification form are returned to you for
inspection.
