TD-CMP Compass

TechDesign Electronics
   
KIT step-by-step construction guide: Partslist here

 

 updated Jan. 15, 2009..
   

 

 PCB, top view (picture)

These parts will fit on this side of the PCB:

  • PIC USB microcontroller 18F2550-I/SO
  • 20 MhZ crystal resonator.
  • Connectors to the LCD (ICSP), RS232 and I²C interfaces.
  • Sensors, chips, transistors, resistors and capacitors.

size = 41,2 x 41,2mm

Double sided and 100% tested PCB with plated-through-hole connections.

All holes are drilled already.

 
 

 PCB, bottom view (picture)
No parts will have to be soldered onto this side of the PCB.

 

 
  Step 1: PCB bottom (drawing)
 
no actions needed here

 

Step 2: PCB top (drawing)
 

IC1 (PIC18F2550) + U$11 (ICSP) + PAD1 + R4
  Use a magnifying glass to do the soldering. First pre-solder pin1 of the chip by adding a bit of solder to this pin. Then place the chips onto the PCB and make sure pin 1 is well placed. The white dots on the drawing point to pin 1 of  the chips. On the PCB, there is a small " ° " etched near pin 1.

 

  • Chip IC1:  PIC18F2550-I/SO
  • Connector U$11 (ICSP and LCD connector, 8-pin SIL)
  • PAD1: !MCLR
  • Resistor R4:  10K SMD (103) or (1002) (on-part values)

 
  PCB, top, after step 2 (picture)
The PIC may now be programmed through ICSP, or you may do this later on.

This is the PCB you get when you buy TD-CMP KIT1

 

 
 
  Step 3: PCB top (drawing)
  3x ICs, 2x transistors, a LED and a crystal resonator
 

ICs:

  • IC2: TLC272C opamp

  • IC3: KMZ51 sensor

  • IC4: KMZ51 sensor

Transistors:

  • T1: FMMT617

  • T2: FMMT717

U$2: Crystal resonator 20MhZ (presolder the middle pcb-middle pin first)

LED1: 3mm low power LED (2...3 mA) Kathode (- pin) is closest to the leftt-hand pcd corner.

 
  Step 4: PCB top (drawing)
4 connectors
Connectors:
  • JP2: RS232 (4-pins SIL)
  • JP3: I²C+ (6-pins SIL)
  • JP4: POWER SOURCE  (3-pins SIL)
  • U$1 (USB mini-B connector): first remove the 2 rectangular green layers from the pcb at the connector rear edges. Scratching a bit with a sharp cutter will do. Now cut the two middle grounding connector  pins away with a sharp cutter: see picture below:

 
  PCB, top, after step 4 (picture)
 
All important parts are now done.

We're almost through.

 

Step 5: PCB top (drawing)

5 resistors and 16 capacitors
 

Resistors:

  • R1, R2: 10K (103) or (1002) (on-part values)

  • R3: 2K2 (222) or (2201)

  • R6, R7: 270K (274) or (2703)

  • R8: 47R (47R0) or (470)

 

Capacitors:

IMPORTANT: tantalum capacitors +pin is marked by coloured band

  • C1: 0,47...1µF polarized SMT or tantalum case B

  • C2: 33...47µF tantalum case B or C

  • C3, C4, C5, C6, C12, C16, C17, C18: 100nF ceramic

  • C13:  33...47µF tantalum case B or C

  • C14: 4,7µF/25V case B or C

  • C10, C15, C19, C20: 2,2µF ceramic
 
 
 

 

PCB, top, after step 5 (picture)
 

That's it! You now have completed the TD-CMP KIT1 compass.

Have lots of fun building it!

Cleaning of the pcb to remove flux may be done with a PCC (printed circuits cleaner,)

Have a look at the TD-CMP project page to get it working. You'll need to connect JP4: POWER SOURCE  (3-pins SIL) according to the power source:

  • USB powered: Connect pin 2 to pin 3 (middle and corner right pins connected.)
  • External power +5V via JP3: Connect pin 2 to pin 1 (middle and left pins connected.)

You will also need to do the tilt-roll and compass calibrations, see the TD-CMP project page for details.
 

 

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