kit assembly guide - bitscope

BITSCOPE Mixed Signal Capture Engine

Kit Assembly Guide

B I T S C O P E M I X E D S I G N A L C A P T U R E E N G I N E

Kit Assembly Guide

Bitscope Designs Suite 1A2, 410 Elizabeth St.

Surry Hills NSW 2010 Australia

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Table of Contents

1 Parts Identification __________ 1

1.1 Before You Begin___________ 1

1.2 Kit Contents_______________ 1

1.3 Special Parts_______________ 2

2 Changes ___________________ 5

2.1 PCB Errata _______________ 5

2.2 R3 Change ________________ 5

2.3 R25 Value _________________ 5

2.4 C27 Modification ___________ 5

2.5 A/D Module _______________ 6 2.5.1 Both Exar and TI A/D Modules_ 6 2.5.2 TI ADC5540 A/D Module Only 6 2.5.3 Exar 8786 A/D Module Only___ 6

2.6 Crystal Speed______________ 8

2.7 ICSP Connector____________ 8

2.8 Reset Connector____________ 8

2.9 Capacitors C56, C57, C59____ 8

2.10 Trimpots_________________ 9

3 Parts Placement____________ 10

3.1 Where the Special Parts Go _ 10

3.2 Proper Parts Placement ____ 10

3.3 Changes and Errata _______ 10

3.4 Oscillator and Crystal______ 12

3.5 Voltage Regulators ________ 12

3.6 Passive Components _______ 14

3.7 Transistors _______________ 14

3.8 End Panels _______________ 14

3.9 LED Indicators ____________15

3.10 Mounting “Spock” ________15

3.11 IC’s and SRAM’s _________16

3.12 Final Assembly ___________16

4 Calibration________________ 18

4.1 Burn-In___________________18

4.2 Channel A/B Zero Offset ____18 4.2.1 Channel A ________________ 18 4.2.2 Channel B_________________ 18

4.3 A/D Module _______________18 4.3.1 ADC Span ________________ 18 4.3.2 ADC Mid Point ____________ 18

4.4 Final Check _______________19

5 Tips _____________________ 20

5.1 Special Parts First __________20

5.2 Clean Component Leads ____20

5.3 Removing a Misplaced Part __20

5.4 Additional DIP Sockets______20

5.5 Power Supply______________21

5.6 Serial Port Cable ___________21

5.7 Logic Analyzer Cable _______21

5.8 Carry Case________________21

6 Beginner’s Guide __________ 22

6.1 ESD Precautions ___________22

6.2 Soldering Tips _____________22

6.3 Polarity___________________23

6.4 Resistors__________________24


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1 Parts Identification This section explains how to correctly identify the parts in the kit.

1.1 Before You Begin In order to avoid misplaced parts; take the time to positively identify everything before assembly is started. Print a copy of the Schematic and Bill of Materials to help identify the parts and assist in placing them on the board. Make note of any changes listed in the Changes section of this manual and the Notice to Kit Builders supplied with the kit. This is important! A Beginner’s Guide is included in this manual to assist first-time builders. If this is your first project of this type, take the time to look at this section. It contains important information to help prevent common assembly mistakes. The more experienced builder should have no trouble assembling and calibrating the Bitscope. Be sure to look at the Tips section for some helpful ideas.

1.2 Kit Contents The Bitscope Kit-03 contains everything you need to assemble a working Bitscope, while Kit-02 contains everything except for the case and end panels. Note that the Bitscope (without its case) will fit into a 5¼” drive bay. This could be helpful if used in a dedicated PC application. In either case, you will also have to supply a 12V/1A AC power supply and test leads and probes. Some recommendations may be found in the Tips section. Let’s get started!

Section

1


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Figure 1-1 Bitscope Kit-03

Take the main components out of the box, you should have everything shown above (Fig. 1-1).

1.3 Special Parts Some parts are “special” and must be properly identified. They will be installed first, to avoid confusion later. There are also some parts that should be installed on a specific area of the board, although they will fit somewhere else. Make sure these parts are placed in the indicated positions on the board (refer to Section 3).


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Figure 1-2 Inductors and Poly-Fuses

The inductors (L) and Poly-Fuses (R) look like resistors and capacitors, but they’re not. Place them first (refer to Section 3).

Figure 1-3 C32 & C34

Capacitors C32 and C34 are 100 nF 63v Poly cap.’s. Place them next (refer to Section 3).


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Figure 1-4 RN1

The Logic Pod Terminating Resistor RN1 has a dot to identify pin 1. Be sure to place it correctly on the board (refer to Section 3).

Figure 1-5 DB25 I/O Connectors

The DB25 Connectors must be installed properly to ensure that all cables and Pod Devices may be connected properly. On top is a DB25RA/M (Male), and below it is a DB25RA/F (Female). Make sure they are placed correctly (refer to Section 3).


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2 Changes This Section Illustrates changes, errata, and optional configurations

2.1 PCB Errata There is only one known PCB errata at this time. The silkscreen legend for C39 is incorrect. The positive (+) lead should be placed next to C37.

2.2 R3 Change R3 has been changed from 4.7K to 1K.

2.3 R25 Value R25 is 10K, it is not listed on the Bill of Materials, however, it is marked correctly on the PCB silkscreen.

2.4 C27 Modification Replace C27 with a 100 pF 50V/ 1K series RC Circuit (Fig. 2-1).

Section

2


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Figure 2-1 C27 Modification

RC Circuit in place of C27 showing a neat arrangement (the capacitor and resistor shown were not kit parts). Also shown is the A/D Module configuration jumper (JP-3). Place a link or jumper in the positions indicated.

2.5 A/D Module 2.5.1 Both Exar and TI A/D Modules Perform the following when using either A/D Module:

1. Place a link (or install a 3-pin SIP header and jumper) to connect positions 2 and 3 in the jumper position (JP-3) near the A/D Module socket (Fig. 2-1).

2.5.2 TI ADC5540 A/D Module Only Perform the following operations when using the TI ADC5540 A/D Module:

1. Omit diodes D5 and D6 from the main board.

2. If using a 50Mhz. oscillator, disable the Clock Doubler circuit (Fig. 2-2). Do this by omitting R11 from the main board, and adding a link in place of C54.

3. If using a 40Mhz. Oscillator, the Clock Doubler circuit may be enabled. Refer to the Bitscope web-site TI 5540 section for more details regarding this option.

2.5.3 Exar 8786 A/D Module Only Perform the following operations when using the Exar 8786 A/D Module:

Connect pos. 2 and 3


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1. Install diodes D5 and D6 on the main board.

2. Solder two 100nF capacitors to the bottom of the main board between pins 11/12 and 16/17 of the A/D socket (Fig. 2-3).

3. Disable the Clock Doubler circuit. Do this by omitting R11 from the main board, and adding a link in place of C54 (Fig. 2-2). It is not recommended to run the Exar ADC with a clock rate higher than 25Mhz.

Figure 2-2 Clock Doubler

The Clock Doubler disabled – notice the link in place of C54 (R11 is omitted also).

Link in place of C54


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Figure 2-3 Capacitors added to A/D socket

The two 100 nF capacitors are only necessary when using the Exar 8786 A/D Module.

2.6 Crystal Speed Depending on the PIC/ Firmware configuration, there are a few choices regarding the crystal. Kits supplied with a PIC 16F84 may not use anything faster than 10Mhz. A 16F84a will run at 20Mhz. , but the firmware must also support this clock rate. Currently, it does not, but may in the future to improve data transfer rate (through the serial port).

2.7 ICSP Connector The In-Circuit Serial Programming connector (JP-1) is not necessary. There is a place for it on the main board, but this is simply left unpopulated.

2.8 Reset Connector The Reset connector (JP-2) is not necessary. There is a place for it on the main board, but this is simply left unpopulated.

2.9 Capacitors C56, C57, C59 These are optional high frequency compensation capacitors. They are generally not needed. Refer to the schematic for additional information.


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2.10 Trimpots Some trimpot values are different from the schematic. The new values are as follows:

1. RV-1 – 5K

2. RV-2 – 500


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3 Parts Placement This section will show where to place the parts on the main board.

3.1 Where the Special Parts Go After identifying the special parts (refer to Section 1), they must be properly placed on the board. Use the picture in this section (Fig. 3-1) as a guide.

3.2 Proper Parts Placement A few parts must be placed in the right spot, although they might fit somewhere else. Use the picture in this section (Fig. 3-1) as a guide.

3.3 Changes and Errata Some changes have been made to the design to accommodate the new A/D module, as well as to improve the performance. Refer to Section 2: Changes for details regarding important updates and amendments.

Section

3


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Figure 3-1 Bitscope Main Board

The Main Board showing where to place the Special Parts. Use the chart below to place the parts correctly.

1. Fuse 1- 500mA Poly Fuse (Fig. 1-2).

2. Fuse 2 - 500mA Poly Fuse (Fig. 1-2).

3. L1- Inductor: 150uH Axial RF Choke (Fig. 1-2).

4. L2- Inductor: 150uH Axial RF Choke (Fig. 1-2).

5. C32- Capacitor: 100NF 63V MKT Poly 5mm (Fig. 1-3).

6. C34- Capacitor: 100NF 63V MKT Poly 5mm (Fig. 1-3).

7. DB25RA/M Connector (Fig. 1-5).

8. DB25RA/F Connector (Fig. 1-5).

9. RN1 Pin 1 Position (Fig. 1-4).

1

7

2

6

8

4

3

5

9


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3.4 Oscillator and Crystal The Oscillator and Crystal must be carefully mounted. The oscillator has one square corner that indicates pin 1. The Crystal should lay flat (bend the leads) and a piece of bus wire may be used to secure it to the board (Fig. 3-2).

Figure 3-2 Oscillator and Crystal

The Oscillator and Crystal properly placed on the Main Board.

3.5 Voltage Regulators There are two types of voltage regulators. U9 and U11 are 7805 +5V 1A positive voltage regulators. U10 and U20 are 7905 –5V 1A negative voltage regulators. Make sure they are placed properly on the main board (Fig.’s 3-3, 3-4, 3-5).

Pin 1 (square corner)


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Figure 3-3 Voltage Regulator

A Voltage Regulator showing how to bend the leads and install the insulating washer.

Figure 3-4 Regulator Insulating Pad

The Voltage Regulator Insulating Pad placed properly on the board.

Insulating Washer


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Figure 3-5 Voltage Regulators

Voltage Regulators placed on the main board showing proper hardware installation. The nuts must be on top or one of them will interfere with the Analog Ground Jack.

3.6 Passive Components After the special parts are placed, and any changes noted (see section 2), the passive components (resistors, capacitors, diodes) may be installed. Notice that some capacitors are polarized so be careful. If you have trouble reading the resistor values, see the Beginner’s Guide in this manual for help.

3.7 Transistors Notice that there are three BC558 PNP transistors and three BC548 NPN transistors. Don’t mix them up! Don’t confuse them with the four JFET’s either.

3.8 End Panels Before installing the end panels, make sure all of the connectors and switches are placed. Test fit the end panels into the case (some filing may be necessary). The end panels are used to help align the LED’s, so make sure they’re ready to go in. Use the connectors to hold the end panel to the main board assembly and proceed to solder the LED’s in place.


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3.9 LED Indicators The LED’s require care to ensure they are bent and placed correctly. If you don’t know how to determine the polarity, see the Beginner’s Guide. The best way to bend them is to place the ridge on the LED body even with the edge of the board, and put the pliers on the leads just behind the pads. If in doubt, make the bend a little bit farther away from the LED body and push the LED back when the end panel is installed. Then solder them in with the end panel in place.

3.10 Mounting “Spock” Be very careful when mounting “Spock” (the Lattice chip). Make sure you know where pin 1 is both on the chip and on the socket (Fig.’s 3-6, 3-7)!

Figure 3-6 "Spock"

Here’s a picture of “Spock” showing how to identify pin 1.

Pin 1


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Figure 3-7 "Spock" mounted in the socket

“Spock” on the board properly mounted in the socket.

3.11 IC’s and SRAM’s The IC’s and memory chips may be soldered into the board (except the PIC) or placed in sockets. The most reliable method is, of course, to solder them in. See the Tips section for some ideas.

3.12 Final Assembly Install any loose chips in their sockets and check the board for any unsoldered leads, or “empty” pads. Finally, install the five standoffs to the board snugly. Slide the main assembly into the case and tighten all five screws. Remove the screws and the main assembly, and tighten the standoff screws securely. The Board is now ready to be calibrated before re-installing it in the case.


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Figure 3-8 Assembled Main Board

The finished Main Board showing everything but the end panels.


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4 Calibration This section describes calibrating the Bitscope

4.1 Burn-In Before attempting to calibrate your Bitscope, check for any “solder bridges” or shorts on the main board. Make sure each chip is properly installed (polarity) and all the leads are soldered. As a safety precaution, you might want to leave the PIC and the Lattice chip out, and power up the circuit. Check for proper voltage on the supply and ground leads of all the IC’s. Check the regulators and verify both supply rail voltages. If all is well, install the PIC and Lattice chip, and let the circuit run for about a half an hour. This will not only prove the circuit’s integrity, but will also allow the chips and FET’s to reach operating temperature.

4.2 Channel A/B Zero Offset Using a DVM put the ground lead on the AGND Test Point (near the A/D socket). You don’t need to ground the input BNC’s because they’re pulled down with 1M resistors internally.

4.2.1 Channel A Adjust RV-3 to get zero volts on U23 pin 6.

4.2.2 Channel B Adjust RV-4 to get zero volts on U24 pin 6.

4.3 A/D Module 4.3.1 ADC Span Adjust RV-2 until there is 1V between Test Points TP-3 and TP-4.

4.3.2 ADC Mid Point Adjust RV-1 until there is zero volts between Test Points TP-5 and TP-4.

Section

4


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4.4 Final Check The last thing to do is connect the Bitscope to a PC and verify operation. Check the Bitscope Web-site for the latest software. Make sure the software can read the firmware ID from the Bitscope, then initiate a trace. If all is well you will be rewarded with a display of data on the screen. As you work with the Bitscope, you will begin to appreciate the elegance of the design. By using the Pod interface, it is possible to adapt the Bitscope to work with a wide range of signals. You now have a truly valuable piece of equipment at your disposal.


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5 Tips This section includes tips and ideas for working with the Bitscope.

5.1 Special Parts First It is recommended that all the special parts are identified and placed first. This will eliminate the possibility of an improperly identified part being installed in the wrong place. Building a kit is like a multiple-choice test- it is impossible to get only one wrong answer!

5.2 Clean Component Leads It is a good idea to clean the component leads with some Scotch-Brite before installing them. This will ensure a good solder joint with maximum reliability.

5.3 Removing a Misplaced Part In the event that a part does need to be removed, some precautions should be taken. Notice that the Bitscope uses a two layered board. Don’t try to remove a component by simply heating the joints and prying the part out! This will most certainly damage the board. Use a Solder Sucker tool first, then clean up the pads with Solder Wick. Heat the wick with the iron to draw the solder off the pad. If a large DIP part is being removed, you may want to consider cutting the leads and replacing the part. The part is cheaper than the board! Don’t allow heat to build up when cleaning up the area. This may cause the artwork to lift and ruin the board. Work slowly allowing time for things to cool.

5.4 Additional DIP Sockets While sockets are supplied with the kit for the PIC, the A/D Module and the PLD, you may want to add one for the 74HC573 (20 DIP). This would allow changing to a 74HCT573 (TTL compatible) should the need arise. It is also a good idea to socket the SRAM chips (28 SDIP).

Section

5


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5.5 Power Supply The Bitscope requires a 12V/1A AC Power Supply. Do not use a DC supply! A wall-type 1A supply will work fine. These can be purchased from most Electronics Suppliers.

5.6 Serial Port Cable The serial port interface connector on the Bitscope is a DB25RA/F type. You may use a DB9 – DB25 adapter if necessary. The cable and connectors must not be Null-Modem configured! Use straight pass through connections only.

5.7 Logic Analyzer Cable A simple Logic Analyzer Cable may be used to access the Bitscope Logic Analyzer Function. The connection point is of course the 25-pin POD connector. All you need are the connectors and some wire. A DB25RA/F connector and hood make up the Bitscope interface. For the target interface, Mouser Electronics has some test clips (# 13IC309) which work well. Some heat shrink tubing may be used as a sheath for the wiring. One word of caution: There is no current limit / clamping protection in the Bitscope.

5.8 Carry Case To make your Bitscope and test leads more portable, you may want to look at All Electronics’ part CAT# CSE-17. It’s a low cost Leatherette case that will carry the Bitscope, Wall-plug Power Supply, and test leads in style.


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6 Beginner’s Guide This section includes help for first-time builders.

6.1 ESD Precautions When working with CMOS parts, it is important to prevent Electro Static Discharge. This is easily accomplished by using an “Anti-Static” ground strap. The strap usually fits around the wrist, and is connected to a reliable ground source through a long lead. ESD is caused by two objects having different amounts of stored electrical energy. It occurs more commonly in dry weather, but may in fact happen at any time. The way the ground strap eliminates this is by removing any potential electrical energy from your body. It is also a good idea to work on an Anti-Static mat if possible. This ensures that the components are protected from ESD while they’re on the bench.

6.2 Soldering Tips Soldering is one of the fundamental skills required to assemble electronic devices. The most important requirements of a good solder joint are:

1. Clean components.

2. Clean soldering iron.

3. Correct type of iron

4. Correct solder for the application (size and composition).

5. Sufficient, but not excessive heat applied to the joint.

6. Correct amount of solder (not excessive).

7. Proper cooling procedure.

All of these elements combine to determine the integrity of the solder joint. Here are some guidelines:

1. Clean component leads with Scotch-Brite before placing the component.

Section

6


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2. Make sure the soldering iron tip is properly tinned and kept clean at all times (use a wet sponge).

3. Use a 25 – 35 Watt iron for most assembly work. Be careful if using a 35-Watt iron on small leads because heat will build up quickly. Too small of an iron is not good either because it requires the heat to be applied for a long time before the solder starts to flow.

4. Use electronic grade .032 60/40 Rosin core solder.

5. Heat both the component and the pad with the tip of the iron. A pointed tip works best for fine work. Don’t apply the heat for more than 5 seconds.

6. Apply only enough solder to cover the pad and the lead. Excessive solder does not add strength and increases the chance of a short.

7. Let the joint cool slowly. Do not force cool air over the joint to accelerate the cooling process – this may fracture the joint.

6.3 Polarity Many components must be installed with reference to polarity. Some do not. Generally ICs, some Capacitors, Diodes, LED’s, and Oscillators must be placed with regard to polarity. Resistors and Inductors don’t. Here’s how to identify the polarity of some components:

1. IC’s have a “dot” near pin 1 or a “notch” on the end where pin 1 is located (left side). The socket they go into, or the silkscreen on the board also has a “notch” or “mark” on the end where pin 1 goes.

2. Capacitors are always marked if they are polarized. Either the negative or the positive lead is marked. If there are no markings, then the capacitor is non-polar; meaning it can be installed “either way”.

3. Diodes have a band to mark the cathode. This is the negative (-) lead, or the lead “the arrow points toward” on a schematic.

4. LED’s (Light Emitting Diodes) have two ways to identify polarity. A new LED has one long lead and one shorter lead. The long lead is the anode (+). This only works, of course, unless the leads have been cut! The best way to polarize an LED is by looking at the body of the LED. The flat spot on the body is next to the cathode (-) lead (Fig. 6-1).

5. Oscillators have a square corner or a “mark” to identify pin 1.


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Figure 6-1 LED

An LED showing how to identify the cathode.

6.4 Resistors All resistors use the standard color code to determine their tolerance and value. The main difference is that precision resistors (like the ones supplied with the Bitscope kit) have an extra band in the value field. Where a “normal resistor” has two significant digits, then a zero multiplier value, a precision resistor has three significant digits. This can sometimes cause confusion even for experienced engineers! Here’s an example to help: 5% 100 Ohm resistor: Brown, Black, Brown, Gold. Two significant digits = 10 plus 1 zero. Gold is the tolerance band. A precision 100-Ohm resistor reads: Brown, Black, Black, Black, (Red). Three significant digits = 100 plus no (0) zeros. Red would be the tolerance band. If there’s any doubt, verify your assumptions with a Digital Voltmeter.

Flat identifies the cathode

kit assembly guide - bitscope

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