Introduction 1
1 – 9
serial port, SPORT1, may optionally be configured as two additional
external interrupt pins (
IRQ1
and
IRQ0
)and the Flag Out (FO) and Flag In
(FI) pins.
1.3.2
Timer
The programmable interval timer provides periodic interrupt generation.
An 8-bit prescaler register allows the timer to decrement a 16-bit count
register over a range from each cycle to every 256 cycles. An interrupt is
generated when this count register reaches zero. The count register is
automatically reloaded from a 16-bit period register and the count
resumes immediately.
1.3.3
Host Interface Port (ADSP-2111, ADSP-2171, ADSP-21msp5x)
The host interface port (HIP) is a parallel I/O port that allows for an easy
connection to a host processor. Through the HIP, an ADSP-21xx DSP can
be used as a memory-mapped peripheral of the host. The HIP operates in
parallel with and asynchronous to the ADSP-21xx’s computational core
and internal memory. The host interface port consists of registers through
which the ADSP-21xx and the host processor pass data and status
information. The HIP can be configured for: an 8-bit data bus or 16-bit
data bus; a multiplexed address/data bus or separate address and data
buses; and separate read and write strobes or a read/write strobe and a
data strobe.
1.3.4
DMA Ports (ADSP-2181)
The ADSP-2181 contains two DMA ports, and Internal DMA Port and a
Byte DMA Port. The IDMA port provides an efficient means of
communication between a host system and the DSP. The port is used to
access the on-chip program memory and data memory of the DSP with
only one cycle per word of overhead. The IDMA port has a 16-bit
multiplexed address and data bus and supports 24-bit program memory.
The IDMA port is completely asynchronous and can be written to while
the ADSP-2181 is operating at full speed.
The internal memory address is latched and then automatically
incremented after each IDMA transaction. An external device can
therefore access a block of sequentially addressed memory by specifying
only the starting address of the block.
The byte memory DMA controller allows loading and storing of program
instructions and data using the byte memory space. The BDMA circuit is
able to access the byte memory space while the processor is operating
normally and steals only one processor cycle per 8-, 16- or 24-bit word
transferred.