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Eggtimer Rocketry Eggtimer TRS Assembly Manual

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Eggtimer TRS Flight Computer
Assembly Manual
Board Rev B2c
© 2017 Eggtimer Rocketry
All Rights Reserved

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Summary of Contents for Eggtimer Rocketry Eggtimer TRS

  • Page 1 Eggtimer TRS Flight Computer Assembly Manual Board Rev B2c © 2017 Eggtimer Rocketry All Rights Reserved...

  • Page 2: California Proposition 65 Warning

    The European Union RoHS (Restriction on Hazardous Substances) regulations exempt kits such as the Eggtimer TRS from its regulations, because they are not for resale and since it is well known that hand soldering with non-leaded solder is much more difficult and more damaging to heat-sensitive components.

  • Page 3: Important Regulatory Information

    902-928 MHz band, and therefore must not be used in residential areas. The Eggtimer TRS uses RF modules in the 902-928 MHz ISM band manufactured by Hope RF, model HM-TRP-915. They are intended to be used in the United States or other countries with similar RF band and regulatory rules.
  • Page 4 Guide.. • Read them thoroughly before starting… it will save you some grief later, we promise! • Go to our web site and download the latest firmware version, if your Eggtimer TRS wasn’t shipped with the latest and greatest. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...
  • Page 5 NMEA data wirelessly to your laptop, just like the RX “dongle” receiver. Whichever receiver you choose, we recommend that you build the Eggtimer TRS first, because it’s easier to tell if it’s working, and when you have the RX or LCD kit completed it will be easy to tell if that one is working too since it will be easy to see if they are transmitting/receiving data.

  • Page 6: General Assembly Information

    Each installation step has a check-off line, we strongly recommend that you check them off as you go, and that you perform the steps in sequence. We have listed the steps in order to make it easiest to assemble the Eggtimer TRS, deviating from them isn’t going to make your life any easier.
  • Page 7 If you bought a Starter Set, you’re going to be assembling the Eggtimer TRS transmitter board first, because you’ll need the transmitter to be operational before you can test the receiver board. Both boards have signal status LEDs on their RF modules, so you can pretty much tell if it’s working by the status of the lights;...
  • Page 8 Eggtimer TRS for at least 3 hours. A 350 mAH 7.4V 2S LiPo is ideal, it’s a little smaller and slightly lighter than a 9V battery and will easily power your Eggtimer TRS for over 4 hours.
  • Page 9 Assembling your Eggtimer TRS TX Board Step 1: Sort the Components Before you start soldering anything, you need to lay everything out and make sure that you are familiar with all of components, and that you have everything. (Yes, we ARE human and sometimes make mistakes…...
  • Page 10 22K ohm 0805 SMT resistor (marked “223”) .1 uF 0805 SMT multilayer ceramic capacitors (brown in paper carrier) 10 uF 1206-size capacitors (brown in clear plastic carrier) 6mm x 3mm push button switch 10mm magnetic buzzer 3-pin header 1/32” Brass Antenna Wire (4”) 3 ½”...
  • Page 11 They are marked on the boards, but once again you need to make SURE that you have them in the right place before soldering. Unsoldering parts on a small circuit board like the Eggtimer TRS isn’t a lot of fun, even if you have a vacuum desoldering tool. Trust us, we’ve been there before…...

  • Page 12: Section 1 - Mounting The Gps Module

    GPS module. Lay the Eggtimer TRS PC board down in front of you with the “ANT” side to the left. With some PAPER masking tape, tape the left and right edges of the board to your work...
  • Page 13 “long” row of pads lines up with the “long” row on the board, and that the “half- moons” on the GPS module’s pads are centered on the Eggtimer TRS’s pads. With one hand, hold the module in place, and with the other hand smooth the masking tape down against the top of the module so that it securely holds the GPS module in place.
  • Page 14 very much. You should hold the iron for about 5 seconds after the solder flows, then remove the heat and wait at least 30 seconds before you touch anything. If you do this right, you should see a nice shiny solder joint filling in the gap between the PC board and the GPS module’s pad, with a slight radius as it transitions from the board up to the GPS module’s pad.
  • Page 15 Using as little solder as possible, solder the remaining pads on the GPS module, skipping pads and alternating sides so that you do not solder adjacent pads consecutively. This helps prevent the GPS module from getting too hot. Be sure to allow each solder joint to cool for at least 30 seconds before you move on to the next one.
  • Page 16 Remove the masking tape from the GPS module, and remove the masking tape holding the board to your work surface. Turn the module over, and with two new pieces of masking tape tack it down to your work surface so it will not move (yes, it will be upside-down). You will now be soldering the eight square pads on the bottom of the GPS module to the PC board.
  • Page 17 Inspect all GPS module solder joints with a 10x jewler’s loupe to make sure that they are nice and shiny, and that they properly bridge the GPS module pads and the PC board pads. Leave the board taped down to your work surface for now. Take a break and get a beverage…...

  • Page 18: Section 2 - The Deployment Side

    Section 2 – The Deployment Side Next you will be soldering the SMT components that make up the deployment side of the board. They are to the right of the GPS module. In general, you will be working from the GPS module outwards towards the edge of the board.
  • Page 19 Similarly, solder the LOWER optoisolator into place. Locate the two 10K 0805 SMT resistors immediately to the right of the optoisolators, they will be marked “103” on the board. There are actually a group of four of them, but we are only concerned with the two immediately next to them optoisolators right now.
  • Page 20 Now, solder the OTHER two 10K resistors that are immediately to the right of the ones that you just soldered. Before you go onto the next step, take this opportunity to look at the GPS pads on the right-hand side one more time with your 10x jeweler’s loupe, to make sure that you have good solder joints that cover the pad AND the half-moon pads on the GPS module.
  • Page 21 When you are done, inspect the solder joints to make sure that they are nice and shiny and that there are no solder bridges. Note: A solder bridge in the voltage regulator can cause a short that may destroy your Eggtimer TRS, and possibly your LiPo battery too. Be very careful here!
  • Page 22 Note: A solder bridge in an deployment transistor can cause a short that may destroy your Eggtimer TRS, and possibly your LiPo battery too. It may also possibly cause an unexpected deployment when you connect the battery. Be very careful here!

  • Page 23: Section 3 - The Interface Side

    Locate the spot for the 22K ohm resistor, it’s near the bottom of the board just below the deployment transistors (marked “223”). Solder the 22K ohm resistor (marked “223” in place). Inspect the solder joints with a 10x jeweler’s loupe to make sure you don’t have any solder briges.
  • Page 24 Locate the 2.2K resistor just to the left of the GPS module and just below the 330 ohm resistor that you just mounted (it will be marked “222”). Remove ONE 2.2K resistor (marked “222”) from the tape and solder it in place. Inspect the solder joints with a 10x jeweler’s loupe to make sure you don’t have any solder briges.

  • Page 25: Section 4 - The Processor Side

    Remove the SN74HC02 from it’s package. Note that there is a notch, dot, or bar marked on one end, this should be facing UP. With tweezers, hold the SN74HC02 in place, making sure it’s centered on the pads. If you have trouble with this, you can cut an 1/8” wide strip of paper masking tape and use it to hold the part to the board while you solder.
  • Page 26 once the processor is installed, it is CRITICAL that you make SURE that they are installed correctly and that there are no solder bridges. Locate the 1K resistor just to the left of the optoisolators at the edge of the board (it will be marked “102”).
  • Page 27 Locate the .1 uF capacitor just to the left of the pressure sensor (the small silver part with a hole in it), it will be marked .1 uF. Remove ONE .1 uF capacitor from the tape (it will be brown), and solder it in place. Inspect the solder joints with a 10x jeweler’s loupe to make sure you don’t have any solder bridges.
  • Page 28 Locate the .1 uF capacitor just to the left of the EEPROM, it will be marked .1 uF. Remove ONE .1 uF capacitor from the tape (it will be brown), and solder it in place. Inspect the solder joints with a 10x jeweler’s loupe to make sure you don’t have any solder bridges. __ Cover the pressure sensor, memory, and the two capacitors with a small piece of paper masking tape, but leaving the two sets of pads marked “472”...

  • Page 29: Section 5 - Mounting The Through-Hole Parts

    Section 5 – Mounting the Through-Hole Parts Next, you will be mounting most of the through-hole parts. In general, you will want to use a small piece of paper making tape to hold them in place so they don’t fall out as you turn the board over to solder them.
  • Page 30 Insert the push button switch into the holes on the board. It has a little kink in the leads, so it will stand off about 1/16” if you have the kink centered in the middle of the hole. Turn over the board and solder the leads to the board. Insert the AMBER LED into the holes for the 1S LED, make sure that the LONG lead is in the hole maked “+”.

  • Page 31: Section 6 - Mounting The Rf Module

    Section 6 – Mounting the RF Module You will be surface-mounting the Hope RF radio module to the board, similar to the GPS module. The pad spacing is larger, and the part itself is lighter, so it is much easier to solder. There are no pads on the bottom either, so it should be a breeze once you’ve mounted the GPS module.
  • Page 32 the RF module, if you get the tiniest bit of errant solder on the module chances are excellent that it will be ruined. Solder the TOP RIGHT pad of the Hope RF module to the board. Make sure that the board is properly positioned after you solder this joint;...

  • Page 33: Preliminary Testing

    Solder the remaining pads to the board, waiting 30 seconds between pads to prevent the module from overheating. If you inserted resistor leads into the holes to line them up, be sure to remove them before soldering. Preliminary Testing At this point of construction, your board will actually behave just like an Eggfinder TX board, that is, it will stream raw NMEA GPS data continuously from the RF module.
  • Page 34 The amber light on the the Eggtimer TRS board should start flashing, and you should see coordinates on the LCD display. If you have an Eggtinder RX receiver on 915 MHz, connect it to your laptop, and start a GPS monitoring application such as Visual GPS.
  • Page 35 Locate the spot for the resonator, it’s 3 pads at the bottom of the board right in the middle of the processor, marked “XTAL”. Place the resonator in its place, tape it down so it won’t fall out, turn the board over and solder the pins. Trim the leads flush.
  • Page 36 Locate the spot for the 3-pin header, at the bottom of the board near the left edge of the processor. Tape it down so it won’t fall out, and solder the header to the board. Locate the spot on the board for the buzzer, there are two pads in a square just to the left of the RF module marked “BUZZER”.
  • Page 37 RF signals). You will also need to use an external antenna if you are planning to mount the Eggtimer TRS in a AV bay with allthreads. If you want to track your rocket’s flight as accurately as possible or if you are intending to fly over 10,000’, you may need to use a higher gain antenna, such as a 5 dB dipole antenna.
  • Page 38 Building the “Stick” Antenna Using a hard eraser or emery cloth, clean about ½” from one end of the antenna to remove any signs of oxidation. Bend one end of the 1/32” brass antenna wire in a 90° angle, about 1/8” from the cleaned end.
  • Page 39 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Assembly of your Eggtimer TRS is now complete. Inspect the board carefully, looking for “cold” solder joints or incomplete solder joints. Cold solder joints appear dull instead of shiny, and may appear as blobs of solder and not have the nice “wetting” of the pad that you will see with good joints.
  • Page 40 Once that happens, you know that it’s working, congratulations! To turn off the Eggtimer TRS, simply disconnect the battery. If you want to use a power switch on the Eggtimer TRS, please consult the Eggtimer TRS Users Guide; there are GPS considerations that need to be taken into account.

  • Page 41: Troubleshooting

    Troubleshooting If your Eggtimer TRS doesn’t work after assembly and testing, take a deep breath, get out a beverage to clear you mind, and start troubleshooting… Check Your Solder Joints The very first thing you should do is to check out all of the solder joints under a lighted magnifier, and a 10x jeweler’s loupe.
  • Page 42 Check Your Power Supply Make sure that you are using one of the recommended batteries to test with. Make sure that you have the polarity correct: The RED wires must go to the “+” side and the BLACK wires must go to the “-“ side. Your battery connector must be soldered to the pads marked “BATT” + and -.
  • Page 43 Troubleshooting Tips (in approximate order of likelihood) RED PWR LED doesn’t come on • Check the polarity of the LED… it may be in backwards • Bad solder joint on the RED LED or the 2.2K resistor next to it •...
  • Page 44 Solder ONE of the side pins on the top side to the pad on the top of the board. (Note: You may find that the solder that comes with the Eggtimer TRS kit is too fine for soldering these large pins to the board; if that is the case, use some “conventional” .032” 60/40 rosin- core solder for the outer pins, but you DO need to use the included solder for the center antenna pin.) Let it cool for at least 30 seconds.

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