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Dragon Rider 500 - Parts Listing and Assembly Guide

ECROS Technology can supply a complete kit of parts to assemble your Dragon Rider.  The AVR Dragon can be obtained from Atmel distributors such as Digi-Key and Mouser.  ECROS Technology can also supply your Dragon for a small handling fee in addition to the list price.

User's Guide and Independently Written "Instructable"

As well as on this page, helpful tips on assembling the Dragon Rider 500 can be found in the User's Guide.

An illustrated guide to the assembly of the Dragon Rider 500 has been posted by barney_1 as an Instructable.  Although independently written, this has been reviewed for accuracy and is highly recommended for beginner and intermediate enthusiasts.  Some ideas, such as the Plexiglas® base and additional jumpers and sockets, may be helpful to advanced and professional users.  The summary gives barney_1's overall impressions of the Dragon Rider and you can read in the posted comments the reactions of other people.  Please note that the Instructable refers to the original organization of the "Basic" and "Advanced" parts kit that was changed in May 2011 to avoid a price increase.

Basic Parts Kit Contents

The contents of the ECROS Technology Basic Parts Kit is shown in the table, below.

Qty. Description Ref. Des. Comments
1 8-pin DIP IC Socket U3 ATtiny13/25/45/85 Target Microcontrollers
1 20-pin DIP IC Socket U2 ATtiny2313 Target Microcontrollers
1 28-pin DIP IC Socket U4 ATmega8/48/88/168 Target Microcontrollers
1 40-pin DIP IC Socket U1 ATmega16/32, etc. Target Microcontrollers
6 0.1 µF Ceramic Capacitor C2, C5 to C9 Decoupling of VCC, AVCC and AREF
1 Tactile Push-Button Switch SW0 Target Reset Switch
1 1 kohm, 1/4 W, 5% Resistor R1 Reset Current Limit
1 33 kohm, 1/4 W, 5% Resistor R2 Reset Signal Pull-Up
1 100 ohm, 1/4 W, 5% Resistor R4 Isolation of Analog Supply, AVTG
4 2 row by 5 pin 0.1" Pin Header J1, J2, J3 and J4 Port A to Port D Headers
1 2 row by 5 pin Header Socket Q1 (AVR Dragon) JTAG from AVR Dragon
2 2 row by 3 pin Header Socket Q1 (AVR Dragon) Power and ISP from AVR Dragon
1 1 row by 54 pin 0.1" Pin Header Strip J5, etc. Snap for Various Headers
10 Header Shunts - Configuration, Feature Selection
1 Slide Switch, 0.5 amp SW2 Power ON / OFF from AVR Dragon
4 Pillars, Nylon 4-40, 0.62" tall - Corner Support Pillars
4 Washers, 4-40, 0.032" thick - Extra Height for Corner Support Pillars
4 Nuts, Nylon 4-40 - Corner Support Pillar Assembly to PCB
1 Light Pipe, 0.46" long - Status LED from AVR Dragon
1 Light Pipe Fastening Ring - Fasten Light Pipe to Dragon Rider PCB
4 Bumpon feet, adhesive - AVR Dragon Support
1 1 kohm, 1/4 W, 5% Resistor R3 Bias Current for Voltage Ref. AREFT
1 TL1431 (2.5 V, 0.4%) U5 LM431-type Precision Voltage Reference
2 20 pF Ceramic Disk Capacitors C3 and C4 Crystal Load Capacitors
1 Crystal Socket X1 Machined-Pin
1 7.3728 MHz Crystal X1 Clock Crystal
Basic Assembly Steps

The Dragon Rider requires only moderate skill to assemble.  You should use a good-quality soldering iron with a fine tip and flux-cored solder designed for electronic work.  There is one difficulty to be addressed, which is mounting the header sockets on the undersize of the board while there is room to solder their pins on the topside.  Do not leave the header sockets to last; instead mount them before the headers for High Voltage, ISP and JTAG programming.

The suggested order of assembly, below, is simply to mount parts in order of height from the board.  This allows you to turn the board upside-down to hold components in place for soldering.  If you have the High-Voltage Programming Parts Kit, don't put it to one side and assemble the Basic parts first; assemble both kits at the same time.  Be sure to protect your work surface from heat and abrasion; a piece of card will do this nicely.

Begin with the resistors R1 to R4.  Bend the leads at right angles to match the pitch of the holes in the board and pass them through.  On the back side, bend them sharply at 45 degrees to hold the part in place while you repeat this process for the other components.  Turn the board over and solder the leads.  Snip off the excess flush with the board.  Holding the blades of your cutters flat to the board, rather than facing the tip sharply down, will avoid damaging the PCB traces.

If you are using the ECROS Technology parts kit, the reset switch SW0 is shorter than the IC sockets and can be assembled next.  However, as it is a snap fit and holds itself in place, it can actually be assembled at any time.  If you are using your own parts, don't assemble the reset switch at this point if it is taller than the IC sockets.

The four target IC sockets, U1 to U4 will be next.  Press down on the back of the board while you solder two pins in opposite corners first.  Check that the socket is sitting flush against the board and re-melt the solder if necessary while closing any gap.  Then proceed to solder the remaining pins and clip off the extra length of the pins.

If you intend to use a crystal on the Dragon Rider, this is probably a good point at which to think about this.  See below.

This is about where you should add the radial capacitors C1, C2 and C5 to C9.  Bend the leads to hold them in place as you did with the resistors.

Next, assemble the headers on the left half of the board, J1 to J13.  Do not, at this, time mount headers J17 to J28 or it will be difficult to solder the header sockets, which mount on the bottom of the board.

Before finishing the topside headers, mount the header sockets that connect to the AVR Dragon onto the bottom of the board.  These are not identified on the silkscreen, but it should be completely obvious where they go if you look at your AVR Dragon.  There is a ten-pin socket (2 by 5) for JTAG, two six-pin sockets (2 by 3) for power and ISP and a twenty-pin socket (2 by 10) for High Voltage.  Support the board so that the sockets, inserted from underneath, lie flush to the underside.  Solder opposite corner pins, check and reposition if necessary, solder all pins and clip the leads.  To be sure that everything will line up, consider sliding the header sockets onto your AVR Dragon's headers and placing the Dragon Rider on top.  To solder pins while they are connected to your valuable AVR Dragon, you should be confident of the quality of your soldering iron, or you can unplug it and ground it while you do this.  If you plan to use High Voltage programming and don't have the 20-pin header on your AVR Dragon, you will, of course, have to add it.

The power switch, SW2, being tall, should be one of the last parts to go on to the board.  Just to the right of this switch, there is a footprint for the sub-regulator, U6, that few people will use (see the User's Guide').  If you are not using a sub-regulator, that is if your target is powered directly from the AVR Dragon, install a wire jumper between the top two holes of the U6 footprint (closer to the IC U4).  The bottom hole, closer to the Port B header, J2, is ground, so don't put the wire link in there!

The finishing touches are the non-electrical parts.  Push the light pipe through its hole (near the reset switch) from the top of the board and slide the ring over it on the bottom to hold it in place.  Assemble the four pillars by placing a nylon washer over the threaded end, inserting this end through one of the four corner holes from the bottom of the board and securing it with a nylon nut.  Place the bumpon feet on the bottom of your AVR Dragon in the four corners.  When assembled to the Dragon Rider, both the AVR Dragon and the Dragon Rider will be supported on a flat work surface by the bumpons and pillars, respectively, when the headers are fully engaged in the sockets.  The AVR Dragon's status LED will be visible from the top of the assembly through the light pipe.  If you are using your own headers and sockets and they are of unusual height, you may have to make adjustments in the height of the pillars and/or the feet applied to the AVR Dragon.

The corner pillars for the Dragon Rider have 4-40 tapped holes in the bottom.  So, if you want a semi-permanent assembly, you can hold everything down to a base of some sort (such as Plexiglas) with four 4-40 machine screws.  Even without such measures, the headers and sockets supplied in the Parts Kits hold the AVR Dragon to the Dragon Rider very securely and you can pick up and even shake the assembly without fear of the Dragon taking wing and flying away.

The precision reference supplied as U5 will give you a far more accurate analog reference voltage than is available in the microcontroller.  It is rated at 2.5 volts nominal with a maximum room temperature error of only 0.4% and a maximum drift of 90 parts per million per °C (13 typical).  R3 sets the current to 2.5 mA (the minimum for full performance is 1 mA).  Note that once you have installed R3 and U5, you must not select an internal reference source in your software as it will be shorted to the external reference.

The crystal oscillator circuit consists of the load capacitors, C3 and C4, and the crystal or, preferably, a crystal socket.  It isn't hard to add these parts even after everything else is assembled.  Note that if you solder a crystal directly to the board, you may have problems with High Voltage programming, when the AVR Dragon wants to supply the target clock signal.  This is completely safe, however, if you will only use ISP, JTAG and/or debugWIRE.  Of course, if you want to be able to change the crystal frequency, a socket is necessary.  It may be cheaper to make one by cutting down a machined-pin IC socket than to buy a purpose-designed crystal socket.  This is (ahem) what you will find in the parts kit.

High-Voltage Programming Parts Kit Contents

The contents of the ECROS Technology High-Voltage Programming Parts Kit is shown in the table, below.

Qty. Description Ref. Des. Comments
1 2 row by 10 pin Header Q1 (AVR Dragon) Mount as HV_PROG on AVR Dragon
1 2 row by 10 pin Header Socket Q1 (AVR Dragon) High-Voltage Programming from AVR Dragon
2 2 row by 5 pin 0.1" Pin Headers J17 and J21 High-Voltage Programming Headers
1 1 row by 8 pin 0.1" Pin Header Strip J18, J19 and J20 Snap as required (one spare pin)
2 Header Shunts - High-Voltage Programming Configuration

If you are assembling both the Basic and High-Voltage Programming parts kits at the same time, install the headers after the header sockets on the bottom of the Dragon Rider, as described above.

Optional Parts, Not in Either Parts Kit

Qty. Description Ref. Des. Comments
1 1 nF Ceramic Capacitor C1 Reset switch de-glitching
1 18.432 MHz (or other) Crystal X1 Clock Crystal
1 LM1117-3.3 U6 Target Power 3.3 Volt Sub-Regulation

It has not been found necessary to de-glitch the reset switch.  Therefore, it is recommended that C1 not be installed.

You can use just about any HC-49/U-S or HC-49/U crystal with a nominal frequency that is suitable for the target microcontroller.  If you want the frequency to be accurate, however, you must use a crystal manufactured for parallel resonance with a load capacitance of 18 or 20 pF.  These are easy to find.

The target power sub-regulator deserves special attention.  The footprint for U6 is squeezed onto the PCB in between the AVR Dragon power connector and the switch, SW2.  The heatsink tab is to the left, as marked.  But, if you actually put it here, it will almost surely be in the way.  Most people are not expected to need sub-regulation, but if you do, consider mounting U6 underneath the Dragon Rider board.  With the tab facing down and the pins bent up, it will be out of the way to the left of the 6-pin power connector.