Texas Instruments 99/4A - Page 66

TMS 9901 JL, NL
PROGRAMMABLE SYSTEMS INTERFACE
Peripheral
and Interlace Circuits
Pin Descriptions
Table 4 defines the TMS 9901 pm assignments and describes the function of each pm.
TABLE 4
TMS 9901 AN ASSIGNMENTS ANO FUNCTIONS
SIGNATURE PIN I/O DESCRIPTION
iNYR EQ
ICO (MSB) 15
IC1 14
IC2 13
IC3 (LSB) 12
cr s
so
S1
S2
S3
S4
CRUIN
39
36
35
25
24
CRUOUT 2
CRUCLK 3
BST1 1
V CC
V SS
0
fTJTi
1NT2
INT3
I NT 4
fNT5
rWT6
in T7; pis
(NTs/ P14
fNTg/ P13
INT10/P12
("NTi 1/Pi1
PTT12/P1O
|TJT13/P9
|75T14/P8
1TJT15/P7
PO
P1
P2
P3
P4
P5
P6
40
16
10
17
18
9
8
7
6
* 34
33
32
31
30
29
28
27
23
38
37
21
20
19
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
IN
IN
IN
OUT
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
1/O
I/O
I/O
I/O
I/O
INTERRUPT Request. When active (low)
(NtREQ indicates that an enabled interrupt
has been received. iNTREQ will stay active
until all enabled interrupt inputs are re 
moved.
Interrupt Code lines. ICO-IC3 output the
binary code corresponding to the highest
priority enabled interrupt. If no enabled
interrupts are active ICO — IC3 - (1,1.1.1).
Chip Enable. When active (low) data may be
transferred through the CRU interface to
the CPU. CT K m no effect on the interrupt
control section.
Address select lines. The data bit being
accessed by the CRU interface is specified
by the 5- bn code appearing on S0-S4.
CRU data in (to CPU). Data specified by
S0-S4 is transmitted to the CPU by CRUIN.
When CT is not active CRUIN is tn a high-
impedance state.
CRU data out (from CPUI. When CT is active, data present on the CRUOUT input will be sampled during
CRUCLK and written mto rhe command bit specified by S0-S4.
CRU Clock (from CPU). CRUCLK specifies that valid data is present on me CRUOUT ime.
Power Uo Reset. When active (low) A^T 1 resets ail interrupt mams to 0 ” -esers 1C0 - *C3 « <0 0. 0. 0).
INTERQ • 1 disables the clock, and programs ail t/Q ports to >nputs. RST1 has a Schmitttriger .nout tn
allow implementation with an RC circuit as shown m Figure 7
Supply Voltage. *5 V nominal.
Ground Reference
System dock (o3 in TMS 9900 system. CKOUT in TMS 9980 system)
RST1 1
0
U ]
40
V CC
: ruout j
0
j
39
SO
: ruclk 3
0 ]
34
RO
CRUIN 4
0
]
37
P1
Cl s
0
]
S1
-
ri
INT9 •
c
J
35
S2
in T s 7
□
J
34
iNT7rF15
7 n ?4 1
D
33
TUTs/pie
iNf3 9
□
32
7 n T9/P13
0 10
□ J
31
in T iq / pi 2
iNTREd 11
a ]
30
7^71 vph
lC3 12
]
29
INT12/F10
IC2 13
]
29
INT 13^9
n
1C1 14
J
27
INT14/P0
ICO 15
J
29 rz
]
25
S3
a ]
24 S4
in T i n
a
]
23
INT 15/RT
*5 19
a
J
22
T3
*5 20
c
]
21
M
Group 1. interrupt inputs.
When active (Low) the signal is ANOed with its corresponding
mask bit and •< enabled sent to tne interrupt control section.
INT 1 has highest priority.
Group 2. programmable interrupt (active low) or I/O pms (true logic). Each om is individually proqrammaoie a:
an interrupt, an input port, or an output port.
Group 3. I/O ports (true logic). Each pm IS individually programmable as an input port or an output port.
Fig. 22
57