ADSP-21xx
REV.
–7–
The interrupt force and clear register, IFC, is a write-only
register that contains a force bit and a clear bit for each inter-
rupt (except for level-sensitive interrupts and the ADSP-2111
HIP interrupts—these cannot be forced or cleared in software).
When responding to an interrupt, the ASTAT, MSTAT, and
IMASK status registers are pushed onto the status stack and
the PC counter is loaded with the appropriate vector address.
The status stack is seven levels deep (nine levels deep on the
ADSP-2111) to allow interrupt nesting. The stack is automati-
cally popped when a return from the interrupt instruction is
executed.
Pin Definitions
Table IV (on next page) shows pin definitions for the ADSP-
21xx processors. Any inputs not used must be tied to V
DD
.
Table III. Interrupt Vector Addresses & Priority
ADSP-2105
Interrupt Interrupt
Source Vector Address
RESET Startup 0x0000
IRQ2 0x0004 (High Priority)
SPORT1 Transmit or
IRQ1 0x0010
SPORT1 Receive or
IRQ0 0x0014
Timer 0x0018 (Low Priority)
ADSP-2101/2103/2115/216x
Interrupt Interrupt
Source Vector Address
RESET Startup 0x0000
IRQ2 0x0004 (High Priority)
SPORT0 Transmit 0x0008
SPORT0 Receive 0x000C
SPORT1 Transmit or
IRQ1 0x0010
SPORT1 Receive or
IRQ0 0x0014
Timer 0x0018 (Low Priority)
ADSP-2111
Interrupt Interrupt
Source Vector Address
RESET Startup 0x0000
IRQ2 0x0004 (High Priority)
HIP Write from Host 0x0008
HIP Read to Host 0x000C
SPORT0 Transmit 0x0010
SPORT0 Receive 0x0014
SPORT1 Transmit or
IRQ1 0x0018
SPORT1 Receive or
IRQ0 0x001C
Timer 0x0020 (Low Priority)
SYSTEM INTERFACE
Figure 3 shows a typical system for the ADSP-2101, ADSP-
2115, or ADSP-2103, with two serial I/O devices, a boot
EPROM, and optional external program and data memory. A
total of 15K words of data memory and 16K words of program
memory is addressable for the ADSP-2101 and ADSP-2103. A
total of 14.5K words of data memory and 15K words of
program memory is addressable for the ADSP-2115.
Figure 4 shows a system diagram for the ADSP-2105, with one
serial I/O device, a boot EPROM, and optional external
program and data memory. A total of 14.5K words of data
memory and 15K words of program memory is addressable for
the ADSP-2105.
Figure 5 shows a system diagram for the ADSP-2111, with two
serial I/O devices, a host processor, a boot EPROM, and
optional external program and data memory. A total of 15K
words of data memory and 16K words of program memory is
addressable.
Programmable wait-state generation allows the processors to
easily interface to slow external memories.
The ADSP-2101, ADSP-2103, ADSP-2115, and ADSP-2111
processors also provide either: one external interrupt (
IRQ2)
and two serial ports (SPORT0, SPORT1), or three external
interrupts (
IRQ2, IRQ1, IRQ0) and one serial port (SPORT0).
The ADSP-2105 provides either: one external interrupt (
IRQ2)
and one serial port (SPORT1), or three external interrupts
(
IRQ2, IRQ1, IRQ0) with no serial port.
Clock Signals
The ADSP-21xx processors’ CLKIN input may be driven by a
crystal or by a TTL-compatible external clock signal. The
CLKIN input may not be halted or changed in frequency during
operation, nor operated below the specified low frequency limit.
If an external clock is used, it should be a TTL-compatible
signal running at the instruction rate. The signal should be
connected to the processor’s CLKIN input; in this case, the
XTAL input must be left unconnected.
Because the ADSP-21xx processors include an on-chip oscilla-
tor circuit, an external crystal may also be used. The crystal
should be connected across the CLKIN and XTAL pins, with
two capacitors connected as shown in Figure 2. A parallel-
resonant, fundamental frequency, microprocessor-grade crystal
should be used.
Figure 2. External Crystal Connections
CLKIN CLKOUT
XTAL
ADSP-21xx
