Lucent Technologies DSP1611, Information Manual, Page: 224 / 443

Information Manual DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
April 1998 Serial I/O
Lucent Technologies Inc.
DRAFT COPY
7-15
7.5 Serial I/O Programming Example
(continued)
7.5.1 Program Segment (continued)
buf: y=0x01
*r1=y /* set flag for buf2 */
r0=0x17f /* interrupt pointer to buf2 */
r1=0xff /* program I/O pointer to buf1 */
y=0x1ff /* address of last sample in buf2*/
*r2=y
goto mainprg
7.6 Multiprocessor Mode Description
7.6.1 Multiprocessor Mode Overview
The SIO multiprocessor mode allows up to eight DSP1611/17/18/27/28/29 devices (or DSP16A or DSP16XX
devices that include multiprocessor capability) to be connected together to provide data transmission between any
of the individual DSPs in the system. The SIO ports (SIO1 and SIO2) can be individually configured for multipro-
cessor mode.
Figure 7-11 shows how the DSPs are connected together over a four-wire bus. All of the DSPs have
access to the common data bus and the common address bus. The data rate while in multiprocessor mode is
lower than the maximum nonmultiprocessor rate (refer to SIO multiprocessor timing information in data sheet). For
successful multiprocessor communication with this bus configuration, the following requirements must be met:
Only one DSP can drive the data and address buses at one time. This is satisfied by programming each DSP to
be assigned its own time slot (or time slots) for its turn to transmit. There are eight serial time slots with 16 bits of
serial data in each time slot.
5-4181
Figure 7-11. Multiprocessor Connections
DSP 0
DATA CK ADD SYN
DSP 1
DATA CK ADD SYN
DSP 7
DATA CK ADD SYN