Idma Port; Idma Port Pin Summary - Analog Devices adsp-2100 Manual

11 DMA Ports
11.3
The IDMA Port of the ADSP-2181 is a parallel I/O port that lets the
processor's internal memory be read or written by a host system. The IDMA
Port architecture eases host bus interface design.
Think of the IDMA port as a gateway to all internal memory locations on the
DSP (except for the processor's memory-mapped control registers). The
IDMA Port has a 16-bit multiplexed address and data bus that supports
access to both 16-bit Data Memory and 24-bit Program Memory. IDMA Port
read/write access is completely asynchronous and a host can access the
DSP's internal memory while the ADSP-2181 is operating at full speed.
Unlike the Host Interface Port (HIP) of the ADSP-2171 and ADSP-2111, the
IDMA port does not require any ADSP-2181 processor intervention to
maintain data flow. The host system can access ADSP-2181 internal memory
directly, without going through a set of mailbox registers. Direct access to
DSP memory increases throughput for block data transfers. Through the
IDMA port, internal memory accesses can be performed with an overhead of
one DSP processor cycle per word.
The ADSP-2181 supports boot loading through the IDMA port, through the
BDMA port, or from an external Program Memory Overlay. The BMODE
and MMAP pins select the DSP's boot mode and memory map. Setting
BMODE=1 and MMAP=0 directs the ADSP-2181 to boot through the IDMA
Port. For information on IDMA booting, see "Boot Loading Through The
IDMA Port" at the end of this chapter.
Note: The IDMA port cannot be used to read or write the ADSP-2181's
memory-mapped control registers. See "Modifying Control Registers for
IDMA."
11.3.1
The IDMA Port pins are shown below in Table 11.3.
Pin Name(s)
IRD
IWR
IS
IAL
IAD0-15
IACK
Table 11.3 IDMA Port Pins
11 – 12
* After reset,
each IDMA operation is completed,

IDMA PORT

IDMA Port Pin Summary

Input/
Output
I
I
I
I
I/O
O
IACK
is asserted (low). It stays low until an IDMA transfer is initiated. After
Function
IDMA Port Read Strobe
IDMA Port Write Strobe
IDMA Port Select
IDMA Port Address Latch Enable
IDMA Port Address/Data Bus
IDMA Port Access Ready Acknowledge*
IACK
will again be low.