IC Tester Part 1
Short Description
IC Tester...
Description
IC tester Part 1: circui circuitt des descri cripti ption on and construction
This article describes a stand-alone IC tester for logic ICs ICs (with up to to 24 pins) from from the well-know well-known n 74xx (TTL) and 40xx (CMOS) series. The elementary building blocks that make up the design are an 80C535 microcontroller, a large EPROM, an LCD display, a small keyboard and an RS232 interface. In this first instalment, our main subjects will be hardware-related.
This design was awarded the International First prize in the Elektor Electronics 1997 Design Competition. A condensed description of the project appeared in the January 1998 Supplement on prize-winning contest entries.
Design by L. Lamesch
50
In the January 1998 issue we promised a full-blown and tested version of the IC Tester, complete with PCB layouts and a ready-programmed GAL and EPROM. Many of you will have eagerly looked forward to the present article, which, we hope, lives up to expectation. The IC tester is a fairly complex project, and an interesting combination of mixed-mode (analogue/digital) electronics on the one hand, and software (microprocessor as well as PChosted), on the other. The IC tester is capable of working in stand-alone mode, i.e., any connection to a PC is entirely optional. The standard version of the tester is capable of testing all ICs listed in Table 1. A number of software utilities are available which allow advanced users to add ICs to the library as listed listed in Table Table 1, and this subject will be covered in detail in part 2 of this article. We We do, however, however, reckon that the ‘default’ library will be sufficient in the majority of cases — extending it with ‘new’ devices is specialist work! This tester is a great tool for anyone who’s ever had to do go/non-go testing on a vast amount of integrated circuits from the ‘74’ TTL and ‘4000’ CMOS series. These ICs are still extensively used by hobbyists because (1) they can often be salvaged from surplus equipment or bought ‘ten a penny’ or at least at knock-down prices, and (2) their datasheets are widely available, so you know how to use them in a design of your own. As a matter of course, the tester is also perfectly suitable for use in an electronics repair shop, where it will be necessary from time to time to check suspect devices. Lastly, the IC tester may also be used to identify unknown ICs, i.e., those with obscure print or a label someone painstakingly ground off…
H O W I T W O R KS The circuit diagram of the IC tester is shown in Figu Figure re 1. It may be divided into a digital control (microcontroller) section, a precision power supply, an RS232 interface, a zero-insertion-force (ZIF) socket (which receives the device under test, DUT), a keyboard section, an LCD and a power supply. Elektor Electronics
3/98
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Visit our Web site at http://ourworld.compuserve.com/homepages/elektor_uk
Around the DUT Let’s start with a look at the electronics around the ZIF socket, position IC12. All input pins of the DUT inserted in the zero-insertion force socket may be pulled to the logic high (H) or logic low (L) level using current limiting resistors and appropriate control levels at the outputs of two Z80PIO I/O blocks, IC2 and IC4. The output states of the DUT may be interrogated via the same PIOs for subsequent evaluation by the CPU (IC3). The power supply pins of DUTs with 14, 16, 18, 18, 20, 22 and and 24 pins may be connected to ground or a current-limited supply voltage via BC639/BC640 switching transistors. These are controlled by outputs on counter cascade IC1-IC9. While the PIOs enable the exact logic states of the DUT outputs to be checked (i.e., 0 or 1), ports P1, P4 and P5 of the 80C535 are used to detect which DUT pins represent a high impedance (high-Z). DUT power supply The voltage source used to power the DUT is built around quad opamp IC6. It supplies an accurately regulated voltage of 5.2 V, and its output current is limited limited to about 0.2 A. The output current is converted into a proportional voltage for measurement by the Table 1. Library: 74xxx 74:00 74:01* 74:02 74:03 74:04 74:05 74:06 Parent: 74:05 74:07 74:08 74:09 74:10 74:11 74:12* 74:13 74:14 74:15* 74:16 74:17 74:18* 74:19* 74:20 74:21 74:22* 74:24* 74:25 74:26
80C535 CPU via its AN0 (analogue) input. The current-sense resistors are R94 and R95. The output voltage is 5.2 V rather rather than 5.0 5.0 V (the typical supply voltage of all TTL ICs) in order to compensate the collector-emitter drop of the BC640 transistors when they are switched on. Logic circuitry and firmware EPROM The control program of the IC tester and the test vectors for the ICs that may be tested are contained in a single 27C512 EPROM, which may be obtained ready-programmed from the Publishers under order code 986507-1. 986507-1. Larger (32-pin) EPROMs like the 27C020 or 27C021 may also be used in this design. For the 27C021 EPROM, jumper JP1 has to be set to the A17 position. More about this in next month’s concluding instalment. The selection between the 64-kByte banks in the EPROM is accomplished by outputs B6 and B7 of IC2. These lines are applied to GAL IC5, which contains logic to control the A16 and A17 address lines of EPROM IC7. Basically, Basically, when a 28-pin EPROM is used, JP1 is set to the bevelled edge position (‘A’). When a 32-pin EPROM is used, the A17 signal is required, so JP1 is set to the other position. The 80C535 CPU runs at a clock speed of 12 MHz. The CPU does does not contain firmware code, and fetches all
of its instructions and data from the system EPROM. None the less, it directly controls the LC display and a keyboard with with 6 keys. The GAL, IC5, looks after the address decoding, and also generates the PHI signal for the Z80PIOs, as well as other essential control signals in the circuit. The GAL, like the EPROM, is supplied ready-programmed by the Publishers, the order 986506-1. code is 986506-1. The reason for using the Z80PIO to control and monitor the DUT inputs and outputs is that this chip is the only widely available 16-bit parallel port IC of which all port line directions are individually controllable, while the output drivers for all port lines consist of push-pull circuits. User I/O The system interacts with the user via a small keyboard (circuit diagram in Figure Figure 2), an LED, LED, D6, and and an LCD LCD (liquid crystal display). The LCD is a general-purpose type with 2 ↔16 characters, optionally with back-lighting. Its contrast is adjustable with preset P1. The LED lights to inform the user that the DUT is being powered and should not be removed from the ZIF socket. An RS232 serial interface, traditionally designed around the MAX232, enables the IC tester to (optionally)
Index of ICs that may be tested (default EPROM contents)
74:38 74:39* 74:40 74:42 74:45 74:46* 74:47 74:48* 74:49* 74:51 St,S* 74:51 LS,L 74:54* 74:55* 74:73 74:74 74:75 74:76 74:83 74:86 -C,-L 74:86 C,L* 74:90 74:92 74:93 74:95A,B 74:100 74:107 74:109 74:119
74:139 74:140* 74:147 74:145* 74:148 74:150 74:151 74:153* 74:154 74:155 74:156* 74:157 74:158* 74:159* 74:160 74:161 74:162 74:163 74:164 74:165 74:166 74:168* 74:169 74:170 74:173 74:174 74:175 74:180*
74:239 74:240 74:241 74:242* 74:243 74:244 74:245 74:247* 74:248* 74:249* 74:250* 74:251 74:253 74:257 74:258* 74:259 74:260* 74:266 74:273 74:280 74:283 74:290* 74:293 74:299 74:323 74:347* 74:348* 74:352*
74:386* 74:390 74:393 74:412 74:425* 74:426* 74:445* 74:447* 74:465* 74:466* 74:467* 74:468* 74:518* 74:519* 74:520* 74:521 74:522* 74:533* 74:534* 74:540* 74:541 74:563* 74:564* 74:573 74:574 74:576* 74:580* 74:590
74:596* 74:620* 74:621* 74:622* 74:623* 74:638* 74:639* 74:640 74:641* 74:642* 74:643* 74:644* 74:645 74:646 74:647* 74:648* 74:649* 74:668* 74:669* 74:670 74:682 74:683* 74:684 74:685* 74:688 74:689* 74:699 74:746**
74:758 74:759* 74:760* 74:762* 74:763* 74:810* 74:811* 74:1000* 74:1002* 74:1003* 74:1004* 74:1008* 74:1010* 74:1020* 74:1032* 74:1034* 74:1035* 74:1036* 74:1240* 74:1244* 74:1245* 74:1640* 74:1645* 74:2240* 74:2241* 74:2244* 74:2540* 74:2541*
74:7541* Library: 40xxx 4001 4002 4009* 4010* 4011 4012 4013 4014* 4015 4016 4017 4019 4020 4021 4022* 4023 4024 4025 4027 4028 4029 4030 4040 4041* 4042
4050** 4051 4052 4053 4056 4060 4066 4067 4068 -RCA* 4068 RCA* 4069 4070 4071 4072 4073 4075 4076 4077 4078 -RCA* 4078 RCA* 4081 4082* 4093 4094 4099* 40014* 40102 40103
40161 40162 40163 40174 40175 40192 40193 40194 4502 4508 4510 4511 4512 4514 4515* 4516* 4518 4520 4522 4526 4529 4539 4543* 4555 4556* 4584 4724
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
1 5V
SSTR
1
SOE
15
C2
IC9
EN3
* R25 ... R48 = SMD
SRG8
16
16
C20
IC1
SCLK
3
SD
2
C11
1D
2D
3
IC9 100n
8
100n
8
4
V17
5
V19
6
V21
7
V20
100n
5V 9
10
XTAL
1
SD
2 A13
3
A15
4
WR
5
PSEN
6
RD
7
B7
8
B6
I0
F0
I1
F1
I2
F2
IC5
I3
F3
GAL 16V8
I4 I5
F4 F5
I6
F6
I7
9
F7
12
PIO1
13
PHI
14
EPROE
15
SSTR
1
SOE
15
SCLK
Z3
180 Ω
Z2
180 Ω
Z1
180 Ω
9
R42
8
R41
7 18
27 28
4
G22
V12
29
IORQ
5
G21
G24
30
16
PIO0
6
G20
17
LCDE
7
G7
2D
3
18
A16
14 G10
19
A17
13 G17
I9 9
10
PA1
D1
PA2
D2
PA3
D3
PA4
D4
PA5
D5
PA6
D6
IC2
D7
ASTB
INT
Z80-PIO V9 V10
10
D0
PB0
B6
33
B7
34
12 G12
21
11 G15
17
D0
19
20
D1
D1
20
1
D2
D2
1
40
D3
D3
40
39
D4
D4
39
38
D5
D5
38
3
D6
D6
3
2
D7
D7
2
IEO
PA0
D1
PA1
D2
PA2
D3
PA3
D4
PA4
D5
PA5
D6
PA6
IC4
D7
15 R40 14 R39 13 R38 12 R37 10 R36
PA7
23
24
24
22
22
INT
ASTB
IEI
4
CE
PB3
RD
PB4
IORQ
PB5
M1
PB6
C/D
PB7
B/A
PIO1
35
RD
36 37
PIO0 RD
35
IORQ
IORQ
36
SOE
SOE
37
5
A11
A11
5
6
A14
A14
6
25
PHI
PHI
25
R34
7
R33
CE
29 R30
PB2
RD
PB3
IORQ
PB4
M1
PB5
C/D
PB6
B/A
30 R29 31 R28 32 R27 33 R26 34 R25
PB7
CLK
11
*
Z24
180 Ω
Z23
180 Ω
Z24
180 Ω
Z21
180 Ω
Z20
180 Ω
Z19
180 Ω
Z18
180 Ω
Z17
180 Ω
16
28 R31
*
Z16
180 Ω
Z15
180 Ω
5V
Z14
180 Ω
Z13
180 Ω
P1
Z12
180 Ω
U–
Z11
180 Ω
10K
Z10
180 Ω
Z9
180 Ω
21
BRDY CLK
8
27 R32
PB0
BRDY BSTB
R35
Z80-PIO
IEO
4
9
18
ARDY
5V
23
D0
PB1
LED
74HC4094
IEI
PB2
32
390 Ω
D0
PB1
31
R80
19
ARDY
IC1
C1/ 1D
26
PA0
PA7
16
C2 EN3
I8
11
R43
SRG8 3 2
R44 10
180 Ω
C13
20
R45 12
180 Ω
Z4
74HC4094
R46 13
180 Ω
Z5
11 V24
R47 14
180 Ω
Z6
12 V22
R48 15
180 Ω
Z7
13 V16
26
*
Z8
14
100n
5V C8
C1/
BSTB
K3
17
5V
11 A14 A15 LCDE
LCDE D0 D1
EPROE
5V 5V C5
C1
C2
100n
10µ 16V
D2
5V
D3 D4
R100
1
8x 4k7
R82
D5
1 4x 4k7
D6 D7
100n 32
IC8 74HC573
31
A1 A2
OE/VPP
A3
IC7 D0
13
D1
14
D2
15
D3
17
D4
18
D5
19
D6
20
D7
21
A4
D0 D1 D2 D3 D4
A5
EPROM 27C512/ 27C021
37
A6 A7 A8 A9
D5
A10
D6
A11
D7
A12 A13 A14 A15 A16 A17
12
A0
A0 12
9
D0
D0
52
11
A1
A1 13
8
D1
D1
53
10
A2
A2 14
7
D2
D2
54
9
A3
A3 15
6
D3
D3
55
8
A4
A4 16
5
D4
D4
56
7
A5
A5 17
4
D5
D5
57
6
A6
A6 18
3
D6
D6
58
A7 19
2
D7
D7
59
5
A7
27
A8
26
A9
1D
50
23 A10
C1
25 A11
EN
11
A8
41
A9
42
4 A12
A10
43
28 A13
A11
44
29 A14
A12
45
3 A15
A13
46
2 A16
A14
47
30
A15
48
1
7 1 A
22
P0.1
P4.6
P0.2
P4.5
P0.3
P4.4
P0.4
P4.3
P0.5
P4.2
P0.6
P4.1
IC3
P0.7
P4.0 P5.7
ALE
P5.6 P2.0
P5.5
P2.1
P5.4
P2.2
P5.3
P2.3
P5.2
P2.4
P5.1
P2.5
80C535
P5.0
P2.6 P2.7
P1.7 T2
5V
P1.5 T2EX P1.4 INT2 20
5V
19 18
K4
JP1 C6
17
A
IC8 10
2
P4.7
P1.6 CLKOUT
5V
20
VCC
P0.0
CS 16
68
VAREF VCC VCC
A0 24
11
16 100n
15 14 13
AN0
P1.3 INT6 CC3
AN1
P1.2 INT5 CC2
AN2
P1.1 INT4 CC1
AN3
P1.0 INT3 CCO
3
4
5
T3
R95 1Ω
25V
100n
P3.4 T0
BD139 T1
10µ
P3.3 INT1
PSEN
R98
P3.2 INT0
47k k 0 1
PSEN 49
R85
P3.1 TxD
1M 4
1%
BC547
R86
R92
100k 1% R87 100k R90 1%
C19
12
9 10
8
IC6c
R99
7
R3
6
R4
5
R5
3
R6
2
R7
1
R8
60
R9
61
R10
62
R11
63
R12
64
R24
65
R23
66
R22
67
R21
29
R20
30
R19
31
R18
32
R17
33
R16
34
R15
35
R14
36
R13 3
4
5
14
IC6d
R89 12
k 9 3
RESET X1
27p
M 1
1%
6
7
8
9
WR
1
8x 4k7
2
3
4
Z1
10k
Z2
10k
Z3
10k
Z4
10k
Z5
10k
IC12
Z6
10k
Z7
10k
Z8
10k
Z1
1
24
Z24
Z2
2
23
Z23
Z3
3
22
Z22
Z4
4
21
Z21
Z5
5
20
Z20
Z6
6
19
Z19
Z7
7
18
Z18
Z8
8
17
Z17
Z9
9
16
Z16
Z10
10
15
Z15
Z17
Z11
11
14
Z14
Z18
Z1 2
12
13
Z 13
Z9
10k
Z10
10k
Z11
10k
Z12
10k
Z13
10k
Z14
10k
Z15
10k
Z16
10k 10k 10k
Z19
10k
Z20
10k
ZIF 24
Z21
10k
Z22
10k
Z23
10k
Z24
10k
5
SSTR
24
SCLK
23
SD
2 C17 10µ 16V
40
3 11
12
21
9
5V
5V R96
C9
C15
C18
4
10µ 16V
k 0 1
5
5V
16
IC10
C1– T1IN
T1OUT
T2IN
T2OUT
R1OUT
R1IN
R2OUT
R2IN
14
K1
7
8 C22
C2+
MAX232
100n
15
C2– 6 C21 10µ / 16V
R97
D2
1N4001
27p L A T X
4µ7
2 3 2 S R
13
V-
2 k 2
T2
V+
C1+
R79
k 0 1
39
12MHz
1
10
22
10
C16 10µ / 16V
1 4x 4k7
5V
26 25
R81
SOE
k 1
R88
RD
27
X2
C12
1%
R83
28
X1
k 1
5V
13
1N4148
VAGND
51 38
1n D3
P3.0 RxD
R93
k 0 1
5
PE
EA VSS
27 Ω
4
AN7
P3.5 T1
C4
3
AN6
P3.7 RD
C14
2
AN5
P3.6 WR 1%
9
R2
2
1Ω
1%
8
R1
AN4
U+
R94
7
8
R101
UIN
6
9
1 6V 6V
BC547
U IN
P2
IC11 5V
7805
D4
K2 D1
3 1
IC6a
1N4148 C3
2
1k R91 100k
IC6 = LM324
4
5 R84 8 k 6
IC6b 6
1N4001
U IN
7
C23
IC6 11
100n
C10
C7
470 µ 35V
100n
9 ... 15V D5
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Visit our Web site at http://ourworld.compuserve.com/homepages/elektor_uk
Z7 T18
U+
R67 1k
R78
V9
k 0 1
G7
T11
R74 1k
Z9
U+ R77
V10
k 0 1
T12
R73 1k
Z10 T20
U+
R65 1k
R76
V12
k 0 1
G10
T13
R72 1k
Z12 T22 R64 1k
G12
Z15 T21
U+
R63 1k
R62
V16
k 0 1
G15
T10
R55 1k
Z16
U+ R60
V17
k 0 1
T9
R53 1k
Z17 T19
U+
R66 1k
R59
V19
k 0 1
G17
T8
R52 1k
Z19
U+ R57
V20
k 0 1
T7
R50 1k
Z20 T17
U+
R68 1k
R58
V21
k 0 1
G20
T6
R51 1k
Z21 T16
U+
R69 1k
R56
V22
k 0 1
G21
T5
R49 1k
Z22 T15
U+
R70 1k
R61
V24
k 0 1
9
8
7
6
5
4
3
G22
2
T4
R54 1k
Z24
R103
1
8x 10k
T14 R71
T4 ... T13 = BC640 T14 ... T22 = BC639
R75
1k
G24
k 0 1
980029 - 11
Power supply The on-board 5-volt power supply for the IC tester is based on a single 7805 3-pin voltage regulator (IC11). A small negative voltage is created mainly for older LCDs by a stealer diode (D5) between the negative line of the unregulated input voltage and the circuit ground. This negative voltage provides a proper range for the LCD contrast setting, P1. The circuit may be powered by an inexpensive mains adaptor with an output voltage voltage between between 9 VDC and 15 VDC. Battery Battery powering is also also possible. The unregulated voltage is also applied to the DUT supply discussed above. The current consumption of the circuit will will be of the order of 150 mA.
CONSTRUCTION As you can see from the photographs on this article and the artwork in Figure 3, the printed circuit board designed for the IC tester is densely populated. The board being doublesided and through-plated, production with hobbyists tools will be almost impossible, hence our recommendation to buy it ready-made through our Readers Services or one of the kit suppliers advertising in this magazine. Remember, successful construction almost entirely depends on accuracy and soldering skills. Start by separating the keyboard from the main board. Put the key board section section aside for later. later. Populating the main board may take quite some time as there are relatively many components to sort and solder in place. Resistors, diodes, capacitors, crystal Start by fitting the SMD (surfacemount device) resistors, R25-R48. This should be done with a lowpower (8-watt) soldering iron and lots of care and precision. Use an ohm-meter to check your work on each and every SMD resistor. All other resistors are mounted upright to save space on the board. Make sure you know the value of each and every resistor and capacitor before mounting it. If necessary, use your DMM and the component overlay printed on the board (and shown in Figure Figure 3) to be absolutely absolutely sure. Also, Also, the SIL resistor arrays on the board must be fitted the right way around, so make sure you know where the ‘common’ terminal goes. Likewise, observe the orientation of the elec-
Figure 2. RS232 con nection diagram and circuit diagram of the keyboard.
2
ENT
5V'
S1
R102
1 8x 10k
UP2
S2
K5 2
3
4
5
6
7
8
UP
9 S3
ESC
S4
DWN
S5
5V' D6
DWN2
S6
LED
1 DC DCD D
DB9 DB9
6 DSR 2
K1'
7 RTS
RXD
3
TXD
8 CTS
GND
4 DTR 9 5 980029 - 12
although you have to be careful not to mix up the BC639s and the BC640s. All ICs are mounted in sockets. With the possibility of future extensions in mind, it is recommended to fit a 32-pin IC socket in position IC7. However, as 32-pin wide-DIL are few and far between, you may have to make one yourself by truncating a 40-pin socket. If you use the ready-programmed (28pin) 27C512 EPROM supplied through the Readers Readers Services, its pin 14 should go in socket pin pin 16. In other words, words, the EPROM is then inserted with its corner pins 14/15 close to the edge of the board. The CPU socket has a bevelled edge which is also indicated on the overlay to assist in positioning. The socket in position IC12 is not intended for an integrated circuit and it is fitted at the solder side of the board. board. You can (carefully) solder the socket pins at the component side of the board.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
0 LED 2 C
1 H
3 1 T
0 2 T
0 1 T
9 1 T
9 T
8 1 T
8 T
7 1 T
7 T
6 1 T
6 T
5 1 T 4 1 T
5 C I
R76 R77 R78 R62
C4
1 1 T
1 - 9 2 0 0 8 9 P1
4 3 2 1 4 4 4 4 R R R R
0 1 2 3 4 7 7 7 7 7 R R R R R
R103
1 2 T
8 7 6 5 4 4 4 4 R R R R
R79
----
2 1 T
8 C
IC2
4 5 6 6 R R
2 2 T
H2
R80
1 C I
3 6 R
980029-1
IC4
R11
-
R10 R9
-
2 1 C I
-
1 8 R
-
R13
5 T
H4
R61
R53 R52
R59 R58
R51 R50
R57 R54
C5 C12 5 8 R
D1 C10
- - - - - - 0 9
IC3
R8 R7 R6 R5 R4 R3 R2 R1
3 2 C
IC6
X1
C9
R93 C21
C1
0 0 1 R
C18
3 D
C17
R92 9 1 C
1 K1 0 1 R 2 2 C
C2
R
8 9 R
C16
1 1 C I
T1
IC10
T3
R60
5 7 R 4 C7 T
K3
-
C3
R99
R12
-
P2
R91
A
R82
R24
R84
R83 C6 C13
R55
7 C I
1 P J
0 9 8 7 6 5 4 3 4 3 3 3 3 3 3 3 R R R R R R R R 2 1 0 9 8 7 6 5 3 3 3 2 2 2 2 2 R R R R R R R R
8 C I
IC9
1 1 C
R97 K4
T2
R49
C15
C14
4 5 9 9 R R
2 4 5 D D D
K2
6 9 R 3 H
R56
+
0
1 - 9 2 0 0 8 9
COMPONENTS LIST Resistors: R1-R24,R56-R62,R75R79,R90,R92,R96 = 10k Ω R25-R48 = 180Ω SMD
R93 = 1k Ω 1% R94,R95 = 1Ω 1% R97 = 2k Ω2 R98 = 47k Ω R99 = 27 Ω R100,R101 = SIL resistor array 8 x
C2,C16,C17,C18,C21 = 10 µF 16V radial C3,C19 = 1nF C9,C12 = 27pF C10 = 470 µF 35V radial C14 = 10 µF 25V radial
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Visit our Web site at http://ourworld.compuserve.com/homepages/elektor_uk
4 H
9 8 0 0 2 9 1
H3
5 K
2 0 1 R
2 P U
2 S
6 S
2 N W D
P U
3 S
5 S
N W D
C S E
4 S
1 S
T N E
H1
1 - 1 9 9 D E 2 2 L 0 0 0 0 8 8 9 9
6 D 2 H
Figure 3. Copper track layouts and component overlays (actual size) of the double-sided, through-plated printed circuit board.
Items available from the Publishers: PCB, disk, GAL and EPROM; set, order code 980029-C. PCB only, order code 980029-1. GAL 16V8 only, only, order code 986506-1. EPROM 27C512 only, order code 986507-1. Disk only, order code 986014-1.
980029-1
T14-T22 = BC639 IC1,IC9 = 74HC4094 IC2,IC4 = Z80PIO IC3 = SAB80C535-N IC5 = GAL 16V8 (order code 986506-1)
Miscellaneous: X1 = 12MHz quartz crystal K1 = 3-pin SIL header K2 = 2-way PCB terminal block (pitch 5mm) K3 = 14-pin SIL header
mounted at the solder side of the board (and soldered at the component side). Its long pins receive a mating socket whose pins are soldered to the 14 copper spots on the LCD module. Doing so allows the LCD to be given a
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Trusted by over 1 million members
Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.
Visit our Web site at http://ourworld.compuserve.com/homepages/elektor_uk
Keyboard This is a simpler and smaller board which should not present any difficulty. Although a connector (K5) is indicated on the overlay, the 8-way flatcable between the keyboard PCB and the main board may be soldered directly to the spots at the solder side. One separate wire is used to control the LED, D6. It goes to a solder pin marked ‘LED’ on the main board.
4
Figure 4. The LCD is mounted at a slant angle of about 15 degrees at the solder side of the board.
That concludes the construction of the PCBs. Now’s a good time to review your work so far. Any blatant errors?
TESTING With the ICs still waiting to be inserted in the respective sockets, connect-up the input voltage and run a quick check on the presence of the 5-volt supply voltage at the relevant pins of all IC sockets. Switch off and insert the LM324 (IC6). Connect the DMM to ground and the top wire of R61, switch on again and adjust P2 for a reading reading of 5.2 V. Switch off and carefully insert all ICs. Note their orientations on the board! Switch on again. The LCD should read IC Tester 1:Test Okay so far? Congratulations!
A D J U S T M E N T S The DUT supply output voltage, U +, has to to be set set to 5.2 5.2 V ±0.05 0.05 V usin using g preset P2. Next, P1 is adjusted for optimum contrast of the texts that appear on the LCD. OPERATION The tester is operated using six keys labelled Ent (enter), Esc (escape), dn (scroll down), up, dn2 (fast scroll down), and up2 (fast scroll up). The up and dn keys have an auto-repeat auto -repeat function which causes the repeat rate to be
only those test vectors are used that have the GND and Vcc pins at the same positions. The GND/Vcc pin entry is optional. Next, you can select the libraries that have to be scanned. 3. Retest IC: once an IC has been tested or identified, it may be tested again without having to pick it from the libraries. 4. Trace: all test vectors and the response of the DUT to these vectors appear in succession on the LC display. 5. Options: here, you can define global options. 6. Info: information on version and copyright. 7. Self Check: the IC tester hardware may be checked using this function and a voltmeter.
5
8. Remote Mode: connect a PC to the RS232 interface and debug test vectors using the DOS program TVCHK.EXE. The up/dn keys are used to scroll one item up or down. The up2/dn2 keys do the same, but then five items at a time. The Ent key is used to confirm a selection. Esc, finally, jumps to the main menu.
NEXT MONTH Next month’s second and final instalment will discuss the structure of the various menus which appear on the LCD, as well as the ins and outs of test vector creation, downloading, debugging and EPROM programming. (980029-1)
View more...
Comments
