Small Buff Jtag Megavolt

8/8/2019 Small Buff Jtag Megavolt

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How To Build Megavolts Small Buffered JTAGv1.2

Abstract A JTAG cable should be considered mandatory equipment for any serioustester. It provides a means to backup the information in the receiver and restore it

whenever necessary. This document illustrates the process of building one that is safe touse in any receiver.

An illustrated guide by DO999Revised October 8th , 2002Version 1.02

DO999 @ www.dssword.comor

DO999 @ www.sattech.net


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Preface................................................................................................................................. 1

Introduction......................................................................................................................... 1Assumptions........................................................................................................................ 1

Electrical Schematic by SatFTA......................................................................................... 4

Construction General ....................................................................................................... 5Construction of the JTAG module ................................................................................. 5

Step 1: Initial assembly of the PCB. ........................................................................... 5Step 2: Mount (solder) the main components ............................................................. 6

Step 3: Connect the parts together. ............................................................................. 7Step 4: Add the single 100 Ohm resisitors.................................................................. 8Step 5: Creating a grounding strip .............................................................................. 9

Step 6: Connect wire for Vcc (power) and Ground to the circuit ............................... 9Step 7: IRD JTAG Port Connection.......................................................................... 10

Step 8: Computer (PC) Connection .......................................................................... 11Step 9: Completion of JTAG module. ...................................................................... 12

Installation......................................................................................................................... 13

Installation - PC Connection......................................................................................... 13Mounting the DB25 .................................................................................................. 14

Installation - Connecting to the IRD............................................................................. 14Installation - Power Connection.................................................................................... 15Optional PAD 1 Grounding Switch.............................................................................. 15

Installation Internal Mounting ................................................................................... 16Conclusion ........................................................................................................................ 16

Troubleshooting ................................................................................................................ 16Appendix A Images ....................................................................................................... 17

Internal JTAG for a 3100 .............................................................................................. 17

Standalone JTAG that can be used on any IRD............................................................ 18Model 2700 ............................................................................................................... 19

Model 3100 / 301 ...................................................................................................... 19EJTAG Pinout:.......................................................................................................... 20Model 6000 ............................................................................................................... 21

Appendix B Detailed Parts List ..................................................................................... 22


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How to build Megavolts Small Buffered JTAG v1.2 by DO999 Page 1

Preface

The first thing I want to point out is that this guide is nothing more than an assemblyguide. The credit for the actual circuit design goes to SatFTA. These instructions expand

on the Megavolts Small Buffered JTAG v1.2 documents by adding step-by-step

pictures and some alternative construction techniques. All the real credit belongs to thoseSatFTA and MegaVolt.

Second, I want to mention that the document is fairly long but hopefully that is due to the

level of detail I am putting into it. This project really is fairly simple to construct. Manysections will not apply to you and the JTAG that you will build. You should of course

read the entire document before starting construction. This will allow you to get thenecessary parts and have a good understanding of the options available to you.

Introduction

Megavolt set out to create a buffered JTAG without a Printed Circuit Board (PCB), smallenough to fit inside a DB25 housing. He was quite successful and the design was

brilliantly simple. This guide expands on that by adding in the PCB such that it can bemounted inside the IRD case or a small project box. Examples, information and picturesof various optional parts and mounting techniques will be shown later in this guide.

Assumptions

It is assumed that the reader has a basic level of soldering skill. The construction is fairly

straightforward and with the PCB a beginner should be able to accomplish the task.

Knowledge and understanding of electrical diagrams is not required even though they are

included in the guide.

It is also assumed that you have read Megavolts documents as they provide some detailsand background that I do not. Some of the information presented here is directly fromthat document.


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Purpose

In general, the purpose of any JTAG cable (buffered or not) is to read and write the TSOPchip within the receiver (IRD). The most common reason for using the JTAG is to extract

the BoxKey information from the IRD. Once you have the BoxKeys, you are able to test

options that do not require the use of the smartcard (CAM) such as the Atmega128 orcomputer emulation software. This connection also allows you to create backup imagesof the firmware within the unit. The firmware is the program code that basically makesthe unit work. It is the equivalent to the operating system that you load onto a computer.

Being able to read / write the firmware is important to recover from ECMs or to rollback the firmware to a previous version that may not have anti-testing features in it

(like firmware version E338 on the 3100 IRD). In addition, with great software likeJKeys by Dave2 you cannot only backup the TSOP (or TSOPs since x100 series IRDshave more than one chip) but you can also read and write the EEPROM chip through the

same cable and software. (Note: Wall version 2 also works great on the 3100)

If you have read this far you probably already know why you want to build a bufferedJTAG. Just in case, the brief rundown is that the buffered JTAG supplies data signals andvoltages that are friendly to both the IRD (receiver) and the computer. The simple resistor

style JTAG can use in excess of 5V which is greater than the 3.3V used in the TSOP thex100 series IRD and not only can it result in poor reads / writes but it can significantly

damage the TSOP. This is not to say that it will absolutely happen, just that it could. Theuse of a buffered JTAG alleviates these issues. The resistor style JTAG (which I wontget into here) is great on the x700 (and Im sure other types) series IRD. Personally, I had

nothing but troubles with the simple JTAG on a 3100 and that is when I was convertedand jumped on the buffered JTAG bandwagon.


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Parts List

A detailed parts list, with pictures, is included in the appendix to this document. Partnumbers, approximate cost and supplier information can also be found in the appendix.

In summary, the following parts will be used:

Quantity Description

1 74HC244 Octal 3-state noninverting line receiver chip

1 2.2K Ohm Bussed 9 resistor network (10 pin Single Inline Package[SIP])

2 100 Ohm Isolated 4 resistor network (8 pin SIP)

2 100 Ohm resistor

1 Printed Circuit Board (PCB)

1 DB25 Connector Male or Female depending on your PC parallel cable

1 6 strip of 6 or 10 conductor ribbon wire. (An old floppy cable workswell.)

1 (Optional) DB25 housing Used if you are not mounting the JTAG inside the IRD

1 (Optional) SPDT or SPST switch Used for Power On/Off

1 (Optional) SPDT or SPST switch used to ground Pad 1 on some IRDs. Also amomentary contact switch (push button) works well for this.

1 (Optional) 20-pin socket to mount the 74244 chip not required if you solder the chip

directly to the PCB

1 (Optional) SIP socket strip with 26 pins not required if you solder the resistornetworks directly to the PCB

1 (Optional) Plastic project box required if you are making a portable, external JTAG

6 (Optional) Pogo / Spring pins to connect to IRD JTAG port. Not required fordirectly soldered cabling.

1 Miscellaneous length of wire, solder, glue or other mounting material1 (Optional) 3.3V (3.0V to 3.6V) power source. Battery or transformer. Not requiredfor internally mounted JTAG. [2 x AA batteries for an x100 series or 3 xAA batteries for a x700 series IRD work well]

An internally mounted JTAG using only the mandatory items listed above will run about$10-$15 Canadian. Obviously, the more optional parts that are used, the higher the cost.

The main component is the 744244 chip. Two versions are available. The HC version is

rated for 2v 6v and the HCT version 4.5v 5.5v. The HC version is preferred in

particular for x100 series IRDs. More information can be found here:74HC244 Specs: http://www.fairchildsemi.com/ds/MM/MM74HC244.pdf

74HCT244 Specs: http://www.fairchildsemi.com/ds/MM/MM74HCT244.pdf


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Electrical Schematic by SatFTA

Here is the overall design of what we are trying to make. If you can follow the directions,it is not necessary to understand this drawing.

A simplified drawing mapped onto the board layout would look like this:


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Construction General

The Buffered JTAG consists of the PCB with the various resistors and 74244 chipmounted on it. The connection to the PC DB25, the JTAG port and power will be

described as part of the Installation process.

Construction of the JTAG module

Once again I want to emphasize that these steps are essentially the same as those

published by Megavolt with the addition of a PCB. I also chose to build the JTAG usingsockets for the components because that is the way I was taught and the pictures are

easier to view with them. It is also easier to replace the parts or borrow them for otherprojects. The main reason for using sockets is to prevent damage to the components fromover heating during soldering. Sockets are not required and add to the overall cost of the

project. Feel free not to use them.

Step 1: Initial assembly of the PCB.

Trim (ie cut) legs (pins) 2, 3, 5, 7 & 9 off the 2.2K Ohm resistor network or the SIP

socket as shown below. These pins are not required and will get in the way later if notremoved. Note that Pin 1 of the resistor network is typically on the left side when

viewing the side with printing on it and should be marked with a coloured band or otherindicator such as a dot or triangle.


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Step 2: Mount (solder) the main components

Start by placing the 74244 chip or the 20-pin socket in the middle of the PCB to allow forother components to be located around the chip. Align the resistor networks or SIP

sockets as indicated in the picture. Note the resistor networks/SIP sockets should be

mounted right beside the 74244 chip or 20-pin socket and not as shown. The imagesimply shows the alignment. See the next image for actual placement.

The image below shows the correct placement of the chips / sockets as viewed from thetop of the PCB.

On the back side of the PCB, solder all pins to the connection points on the PCB but donot bridge solder between any of the pins at this time. There should be 20 solder

connections for the 20-pin socket, 5 solder connections for the 10-pin SIP socket (2.2Kresistor network) and 8 solder connections for each of the two 8-pin SIP sockets (100Ohm resistor networks).


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Only 5 connection are required for the 2.2K Ohm resistor network because you removedthe other unused pins.

Step 3: Connect the parts together.

Use solder on the back side of the PCB to bridge a circuit between pins 1, 4, 6, 8, 10 ofthe 2.2K Ohm bussed resistor network and pins 20, 17, 15, 13, 11 of 7444 chip or socket

respectively as indicated in yellow below. ie Pin 1 of the resistor network connects to pin20 of the 74244, pin 4 to pin 17 and so on.

Using the same technique extend the solder from pins 4, 6, 8, 10 of 2.2K Ohm resistornetwork to the adjacent pins (1, 3, 5, 7) of the 100 Ohm resistor network creating a

connection across all 3 pins.

On the other side of the 74244 chip connect pins 3, 5, 7, 9 to pins 1, 3, 5, 7 of the second100 Ohm resistor network.


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Step 4: Add the single 100 Ohm resisitors.

Solder a 100 Ohm resistor to pin 2 of the 74244 chip and a second 100 Ohm resistor to

pin 18 of the 74244 chip.

Note: When installing the resistor connected to pin 18, leave the wire (lead) on theresistor fairly long as you will connect it past the 2.2K resistor network as shown below.Once it is in place, trim the excess wire off with a pair of cutters.


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Step 5: Creating a grounding strip

Connect pins 1, 4, 6, 8, 10, 19 of 74244 chip together to form a common grounding point.Use a piece of solid wire and solder it between the pins listed. Make sure the wire does

not come in contact with anything else. I left the ground wire long in the image in case I

wanted to use it later in the construction process.

Step 6: Connect wire for Vcc (power) and Ground to the circuit

In preparation for connecting power to the circuit, add a red (Vcc) and black (ground)wire (or any colour) connecting Vcc to pin 20 of the 74244 chip and the ground to pin 1

or the grounding strip created in the previous step.

Optionally, the Vcc line can be connected to a power switch if you are using a battery sothat the circuit can be powered off to the save the life of the battery when not required.


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Step 7: IRD JTAG Port Connection

A 6-wire or 10-wire ribbon cable can be used to connect to the JTAG port on the IRD.This may be soldered directly to the IRD or may be connected via the optional pogo pins.

Ultimately, you want this portion or the circuit to be as short as possible. For now, ensure

that you will have plenty to work with as you can easily make it shorter later on. If usinga 10-wire ribbon cable, connect every second wire to the ground line (not shown). By

grounding every second wire you are in effect isolating the signals in the ribbon cableand reducing any noise picked up by the wiring. This makes the signal cleaner and

reduces the potential for problem reads or writes.

Connect one wire to the grounding strip, four wires one to each of pin 2, 4, 6 & 8 of the

100 Ohm resistor network and the 6th wire to the single 100 Ohm resistor.


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Step 8: Computer (PC) Connection

Similarly on the other side of the chip you need to connect a cable (such as Cat 5 networkcable) to the circuit. A DB25 connection will be installed later and this will be connected

to the parallel port on your computer.

Connect one wire to pin 19 of the 74244 chip, one wire to the 100 Ohm resistor and the

remaining 4 wires to pins 2, 4, 6 & 8 of the 100 Ohm resistor network as indicated.

Note, when connecting to pin 19 of the 74244 chip, skip over the contact for the 2.2KOhm resistor network. You should have cut that pin off at the beginning so it will not bea problem. You may alternatively connect this wire to any other convenient grounding

point.


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Step 9: Completion of JTAG module.

If you used sockets, you may now insert the 3 resistor networks and the 74244 chip. Thismarks the end of the basic module construction. All that is left is to connect it up.

Trim the PCB and mount it inside the project box if one is going to be used.


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Installation

Installation - PC Connection

A DB25 connector (25-pin) is used to interface to the computer as mentioned previously.

This connection will plug into the parallel port on the computer. If you already have acable on this port then the easiest thing to do is install the corresponding DB25 connector.

For example, I have a 25-pin male-to-female straight through cable attached to myparallel port already so I wanted a male DB25 for it to plug in to.

There are different types of DB25 connectors. The simplest one is a solder type whereyou solder the wires onto terminals in the DB25. I used a crimp connector type for mine

since I had the parts and crimper tool handy. That is what you will see in the pictures.

As indicated below, you need to connect the wires from pins 8, 6, 4 & 2 of the 100 Ohm

resistor network to corresponding pins 2, 3, 4, & 5 of the DB 25 connector. Additionally,

connect the 100 Ohm resistor to pin 13 of the DB25 and connect a ground wire to pin 25of the DB25.

Important Note: If you need to pass the wiring through a hole in the IRD, the project box

or anything else, do so before connecting the DB25.


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Mounting the DB25

If you are making a stand alone JTAG that will be used on more than one IRD then youprobably want to mount the PCB inside a small plastic project box. You could mount the

DB25 directly into the wall of the box or drill a hole for a wire and put the DB25 into a

housing that you can purchase for a professional look.

Similarly, if you are mounting the JTAG inside an IRD you can mount the DB25 in a slotcut into the casing of the IRD or drill a hole to pass the wire through the case and put a

housing over the DB25. Cutting a slot for the DB25 in the IRD case can be difficult.

Installation - Connecting to the IRD

Connecting the ribbon cable to the JTAG port on the IRD can be tricky because not all

IRDs have the same configuration and the pinout may change between revisions.

However, the basic concept remains the same. You need to connect the ribbon cable tothe TMS, TCK, TDI, TDO, nTRST and Ground lines of the IRD.

The following chart has been included (thanks to SatFTA) but you should check for a

newer version on the internet if your specific model is not included.

Additionally, there are a number of ways to connect the ribbon cable to the JTAG port. Ibuilt a buffered JTAG that I can use on any IRD (that has a port) by connecting theribbon cable to pogo pins. This is similar to the commercial ones that you can purchase.


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My prototype was built using the connector from a commercial JTAG, I simply cut the

ribbon cable and connected it to my circuit.

The second one I built from scratch. I marked the position of the JTAG pads on a piece of

paper and drilled holes into a piece of wood that the pogo pins could fit into. I then used ahot glue gun to build up a block of glue around the pins, which I could shape with a knife

and the glue gun. It fits perfectly into the existing opening in the IRD.

The 3100 (and 5100) take considerably longer to read / write than the 2700 I started on soI decided to mount a JTAG into the 3100 on a permanent basis. This one I wired directlyto the top of the motherboard and I cut a slot into the back casing for the DB25.

This section may seem a little vague, but I will leave it up to you to decide how you will

connect to the IRD. Pogo pins and direct wiring both have advantages and disadvantages.

Installation - Power Connection

The 74244 chip requires power for the circuit to function. If you are building an external

JTAG then the use of a battery or power transformer is necessary. In the two externaltypes that I built I used a 3.5V lithium battery. I installed a switch so that I could poweron the circuit only when required to save battery life. If you use a transformer, simply

unplug the transformer to cut power, no switch required.

On the internally mounted JTAG I found a 3.3V connection on the motherboard (positive(+) side of a capacitor) that I used to power the circuit. I did not see the need for a power

switch since powering the circuit should not affect normal operation of the IRD. Iconnected to capacitor C137 but there are a number of available connection points. Aground point is easy to find. Connect to the side of the casing if you are in doubt

Voltages between the range of 3.0V and 3.6V should be fine for the circuit to functionnormally.

Optional PAD 1 Grounding Switch

A switch can be used to created a ground connection for Pad 1 on the x700 series IRDs.

If the switch is used (on) when A/C power is applied the IRD boots up into a servicemode permitting writes to the TSOP. This is particularly useful for internally mountedJTAGS.


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Installation Internal Mounting

If you are installing the module internally, you can use the same type of plastic standoffthat is used to mount a motherboard for a computer into a case. A local computer store

will probably provide you with a couple at minimal or no cost. Simply trim the plastictabs to make a flat foot for the module to sit on.

Use cable ties to secure the wires to the module and the case. You dont want them loseinside the IRD.

Conclusion

Now that the JTAG is built and installed, grab a copy of JKEYS (version 2.01 is current

as of the time this document was prepared). Grab your BoxKeys and a backup of yourTSOPs and EEPROM. You will be able to sleep better at night knowing you can restore

these whenever necessary.

Troubleshooting

An excellent troubleshooting guide can be found at

http://www.kickinchicken.org/phpBB2/viewtopic.php?t=445 . I hope this link staysactive for a while.


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Appendix A Images

Internal JTAG for a 3100

The following image shows the mounting and connection points (in general) of the JTAGbuilt to connect to the top of the 3100 motherboard and using a slot cut in the case for the

DB25 PC connection.


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Standalone JTAG that can be used on any IRD

This image shows a battery powered JTAG with pogo pins that can be used on any IRDthat has a standard JTAG port.

Here is an image of a pogo style connector made from an old 5.25 floppy connector that

works great on the EJTAG port (top of 3100 motherboard).


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IRD JTAG Connection ImagesThe following images show the Pad configuration for a number of IRDs.

Model 2700

Note: The 2 images have reversed front / back from each other.

Model 3100 / 301

The 3100 has a number of different pin configurations so match the image to your IRD.


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It is also possible to connect to the inside of the 3100 IRD on the top of the motherboard

at the EJTAG port. Note that the connection configuration is completely different fromthe underside connections.

EJTAG Pinout:

Pad #1 Marked as #13 -> TDOPad #3 Marked as #4 -> TDIPad #4 Marked as #5 -> nTRST

Pad #7 Marked as #3 -> TCKPad #9 Marked as #2 -> TMS


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Model 5100 / 501

Model 6000


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Appendix B Detailed Parts List

Most of the parts can be found at an electronic store or on the Internet at www.digikey.ca.The PCB is a Radio Shack part and the Pogo pins were obtained from

www.solarbotics.com.

Detailed Parts List

Qty Description Image

1 74HC244 Chip

Part No: SN74HC244N

Alternate Parts:74HCT244 (For 5VTSOPS only)

Cost: $1.99

* HCT Version Shown *

1 2.2K Ohm Bussed 9resistor network (10 pinSIP)

Part No: 4610X-101-222(2 per package)

Cost: $1.49 per package

2 100 Ohm Isolated 4

resistor network (8 pinSIP)

Part No: 4608X-102-101(4 per package)


2 100 Ohm resistors

Part No: 1/4W-100R-5(5 per package)


Alternate Part: 1/2Wresistor as shown.

1 3.3V Power Source(Optional)Battery or Transformer

2 x AA batteries (3.0V) or 3 x AA batteries (4.5V) can also be used.


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Qty Description Image6 Pogo (Spring) Pins

(Optional)

Part No: PP3

Alternate Parts: Other style

pogo pins

Cost: $0.90Total Cost: $5.40

1 DB25 25-pin connector

Part No: (Dont know, hadsome already)

Alternate Part: Crimp styleinstead of solder style.

Cost: $3.50 (Approx)

1 DB25 Shell

(Optional)

Part No: (Dont know, hadsome already)



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Qty Description Image2 SPDT Switch (Optional)

Part No: 35-001

Cost: $5.49 EachTotal Cost: $10.98

1 20-pin Socket for74HC244 (Optional)

Part No: DM-320STG30-CF

Alternate Parts:Open frame low-profile

Cost: $2.99

1 SIP Socket strip forresistor networks(Optional)

Part No: SIP64S-TG30

Cost: $4.99

1 Project Box (Optional)

Part No: K-JM12-IE-000

Alternate Parts: Any smallproject box

Cost: $2.99


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Qty Description Image1 Circuit Board

Part No: 276-148A (2 perpackage)

Alternate Parts: Any smallproject board


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