Lucent Technologies DSP1611, Information Manual, Page: 280 / 443

DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR Information Manual
Bit I/O Unit April 1998
10-4
DRAFT COPY
Lucent Technologies Inc.
10.1 BIO Hardware Function
(continued)
10.1.4 BIO Pin Multiplexing
The pins for the BIO are shared with functions of the PIO and the VEC[3:0] functions. Table 10-1 shows the corre-
sponding signal names. The bold font indicates the functions that are the default after RESET. The BIO functions
IOBIT[7:4] are selected if bit 12 (EBIOH) of the ioc register is set. The BIO functions IOBIT[3:0] are selected if bit
10 (ESIO2) of the ioc register is set.
Note: After reset, VEC[3:0] are the outputs and are driven low; and if IOBIT[7:4] are to be used as inputs, EBIOH
must be set before the inputs are driven high.
10.2 Software View
The cbit and sbit registers, the flags, and the pertinent instructions make up the software view. Figure 10-4 is a
flow diagram showing the decisions made for each bit to determine the configuration of the BIO. Each decision is
determined by a bit in the designated fields of the sbit or cbit registers. In all cases, the data on the device pins is
stored in the VALUE field of sbit.
5-4204
Figure 10-4. Logic Flow Diagram for BIO Configuration
Table 10-1. BIO Pin Multiplexing
Symbol Symbol
IOBIT0/PB4 IOBIT4/VEC3
IOBIT1/PB5 IOBIT5/VEC2
IOBIT2/PB6 IOBIT6/VEC1
IOBIT3/PB7 IOBIT7/VEC0
MODE?
DATA = ?
DATA = ?
PATTERN
MATCH ?
MASKED
?
IGNORE
INPUT
TOGGLE
OUTPUT
1 TO
OUTPUT
0 TO
OUTPUT
FLAG SETTING
LOGIC
INPUT, 0
OUTPUT, 1
TOGGLE,1 DATA,0
YES, 0
NO, 1
1
0 1
0
YES NO
NO CHANGE
ON OUTPUT
INPUT
OR
OUTPUT?
ENABLE
OUTPUT
BUFFER
cbit HIGH BYTE
cbit LOW BYTE
cbit LOW BYTE
sbit HIGH BYTE
cbit LOW BYTE
cbit HIGH BYTE