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1
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2
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3
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- Retired from public education
- An active model railroader for 6 years
- Electronics, ham radio, woodworking, computers & programming have
been hobbies for decades
- Model railroading is a nice way to utilize those other interests
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4
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- Primarily interested in:
- using my electronics skills to enhance what can be done with a model
railroad
- Building custom circuits for model railroads
- Making presentations & writing articles about how to “roll
your own” circuits to satisfy my teaching instinct!
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5
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- Provide an overview of “hobbyist” microcontrollers
- Show how microcontrollers are programmed and connected to interact with
railroad equipment
- Demonstrate various devices & projects that utilize microcontroller
operation
- (Hopefully) Excite you with the possibilities and enable you to begin
experimenting!
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6
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- We all have an interest in how things work and many of us have enough
knowledge of basic electronics to know that something can be done…
- we just need a bit of
help putting all of the parts together to make it happen!
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7
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- We Already Know About & Have Experience With:
- Batteries & power supplies
- Track wiring & motors
- AC, DC, voltage, amperage & resistance
- LEDs & incandescent bulbs
- Series & parallel circuits
- Switches, relays & transistors
- Programming
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8
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- Inexpensive
microcontrollers allow us to optimize the basic electronics and
programming knowledge that we have so that we can do some amazing
- (and personally
satisfying)
- things!
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9
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- They have been around for almost 20 years
- Usually dedicated to a single purpose
- Small
- Inexpensive (lately!)
- Programmed in BASIC
- No special programmer needed
- Found in many railroading devices (DCC, sound, radio control)
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10
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- Designed in the UK for use in schools
- SUPERB support
- Free manuals, tutorials and software
- Active & helpful forums on their web page & elsewhere on the web
- PICAXE manuals, especially “section 3- Interfacing Circuits”
are super in helping to put it all together on your railroad
- Book: “Programming
& Customizing the PICAXE Microcontroller”
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11
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- Best choice in terms of:
- Capability
- Ease of use
- Cost
- Support
- dave@davebodnar.com
- info@trainelectronics.com
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12
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- Design objectives:
- Alternately flash two red LEDs
- Operate from battery power
- Alter timing and other characteristics from software
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13
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- Then we will modify the circuit to:
- Start from a button push
- Do other “flashing” things by making minor changes in
hardware & software
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14
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- Parts:
- Cost:
- Less than
- $10.00
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15
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- Software: free from www.picaxe.com
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16
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- Other items needed:
- Any Windows PC with serial port (or USB to serial adapter)
- Programming cable
- Needs only 3 wires - can use an old mouse cable
- Soldering iron & wire cutters, etc.
- A Solderless Development Package is available from www.phanderson.com
for < $20.00
- 4 to 5.5 volt power supply (3 @ AA cells)
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17
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18
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19
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20
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- Program 1:
- Notes:
- “start” is just a label telling the “goto”
where to go
- the program remains in the chip’s memory until it is manually
erased or overwritten.
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21
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- Program 2: modified to flash for 10 seconds and turn
- off for 10
- seconds
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22
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- Hardware modification for button or reed switch activation:
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23
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- Program 3: modified to flash 5 seconds on each button push
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24
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- Add a second sensor so that the light goes on when it passes one
sensor…
- …and goes off when it hits the other sensor.
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25
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26
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- The two sensor crossing light control can easily be modified to make a
“safe crossing”
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27
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- When the first sensor is reached the power is removed from the secondary
line
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28
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- Once the main line has passed the second sensor the power is restored
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29
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- We substitute a relay for the LEDs.
It controls the power to the secondary line
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30
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- A clever use of diodes allows one relay to control the train movement
based on direction of travel
- The train never
- stops after it
has
- passed the
- crossing, only
- before
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31
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- More sophisticated optical sensors only release the stopped train after
the last car of the main line has passed
- End Digression #1
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32
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33
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- Design objectives
- Gradually brighten a bulb or LED to near full brightness
- Momentarily flash to full brightness
- Gradually dim till off
- Delay for a set time
- Repeat
- Able to use LEDs or incandescent bulbs
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34
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35
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- Parts
- Adds one resistor and one transistor to the original flasher circuit so
that the PICAXE can control a high current bulb
- The most significant changes are to the software
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36
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37
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38
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39
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40
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- The transistor makes it possible to drive a very bright bulb
- Substitute a motor for the bulb and you can control a train’s DC
motor!
- The size of motor is only limited by the size of the transistor
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41
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- Lights
- Motors
- Turnouts
- Relays
- Most electrically powered devices
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42
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- LEDs have certainly come a long way in the last 10 years
- They are bright enough to be used as headlights on locomotives
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43
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- Groups of LEDs can be configured to do some remarkable things
- …like creating a realistic Mars light
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44
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45
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- Or even a headlight that is too bright to view directly
- That can turn into a single bulb Mars light
- End Digression #2
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46
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- Time
- Switches of all kinds
- Toggle switch
- Push button switch
- Reed switch & magnet
- Any type of sensor
- Motion, sound, temperature, light, etc
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47
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48
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49
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50
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51
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52
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53
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54
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55
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56
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57
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58
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59
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60
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61
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62
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63
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64
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65
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66
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67
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- Final design:
- 4 line x 20 character backlit LCD display
- Supports scales from 1:1 to 1:220
- Common scales identified by name
- Track-side sensors
- Counts laps
- Gives speed in real & scale MPH
- Option to “beep” out speed
- English or Metric units
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68
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- Wireless option:
- Uses radio transmitter on a modified car
- Senses train speed and sends it to the display unit
- Also can report voltage and current on a battery operated engine
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69
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- Voltage and Current can also be included in the packet that is
transmitted
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70
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- Originally designed to operate the motor on my holiday incline
- Repurposed the Speedometer by adding a power transistor, relay and
additional control buttons
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71
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- BARC
- 2 Potentiometers to adjust time / speed
- 2 Buttons to set options
- Mosfet to handle high (10 amp+) current motors
- 3 LEDs to show time & laps completed
- 176, 172, 167, 163, 158, 154
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72
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- Dual tower lift bridge
- geared stepper motors
- TV remote control programming
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73
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- Crossover collision avoidance control
- Main line & trolley point-to-point cross
- Sensors operate trolley and stop or start it based on the position of
the train
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74
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- Complete 3 train switching controller
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75
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76
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Notes
