Here is a way to connect a Basic Stamp to a firecracker.

For details on the basic stamp, look at the ASP and our PAK coprocessors at http://www.al-williams.com/awce

Under the hood it is simple to connect the Firecracker to the Stamp. I took a female DB9 connector and wired it like this:

DB9 pin Stamp connection

• 4 - P0
• 5 - Ground
• 7 - P1

Using the code is simple.

• First call resetfirecracker to get everything to a known state.
• Then you can set the house variable and unit variable to address the device you want to command. To talk to house A, for example, set house to 0. The unit is a number from 0 to 15. You also set cmd to what you want to do (0=off, 1=on, 2=bright, 3=dim).
• Finally, call sendcmd and you are done.

The example program below uses switches wired to P8, P9, P10, and P11. The switches connect between the pins and ground. Each pin also has a pull up resistor (say 10K or 22K) so the pin reads high when the switch is open and low when you close the switch.

The example program turns off all the devices so they are in a known state. Then when you press a button it toggles the state of the corresponding device. Of course, you could write as fancy a program as you wanted to take the time to write. For example, you could use a light sensor to turn the lights on and off automatically. Or light them according to a timer -- use your imagination.

' http://www.al-williams.com/awce

' Wire Ground (DB9 pin 5)

' DTR (DB9 pin 4)

' RTS (DB9 pin 7)

rts con 1

dtr con 0
 
 

' The Firecracker header (2 bytes)

h1 con $D5

h2 con $AA
 
 

' the Firecracker footer (1 byte)

foot con $AD
 
 

' byte to send

byt var byte

tmp var byte

i var nib

x var nib

state var bit(4)

house var byte '0=A 1=B...

unit var nib  ' 0-15  (must be 0 for bright/dim)

cmd var nib  ' 0=off 1=on 2=bright 3=dim
 
 

gosub resetfirecracker
 
 

' Sample program

main:

' all off

  for x=0 to 3

    house=0

    unit=x

    cmd=0

    gosub sendcmd

    pause 20

    state(x)=0

  next
 
 

mainloop:

  if in11=0 then c0  ' look for buttons on p8-11

  if in10=0 then c1

  if in9=0 then c2

  if in8=0 then c3

  goto mainloop
 
 

c0:

  x=0

  goto ccmd

c1:

  x=1

  goto ccmd

c2:

  x=2

  goto ccmd

c3:

  x=3

ccmd:

  unit=x

  cmd=state(x)+1

  if cmd=1 then gocmd

  cmd=0

gocmd:

   gosub sendcmd

   pause 250

   state(x)=cmd

   goto mainloop
 
 

' End of example program
 
 

' Send command

sendcmd:

  byt=h1

  gosub sendbyte

  byt=h2

  gosub sendbyte

  read housetbl+house,byt

  if unit<9 then lowunit

  byt=byt+4

lowunit:

  gosub sendbyte

  byt=$20

  if cmd=0 then addunit

  byt=0

  if cmd=1 then addunit

  byt=$88

  if cmd=2 then nounit

  byt=$98

  if cmd=3 then nounit

' huh???
 
 

addunit:

  read unittbl+(unit//8),tmp

  byt=byt+tmp

nounit:

  gosub sendbyte

  byt=foot

  gosub sendbyte

return
 
 

' Send 1 raw byte

sendbyte:

  debug hex byt," "

  for i=0 to 7

   if byt & $80 = $80 then xmit1

   gosub send0

nextbit:

   pause 1

   byt=byt*2

   next

   return
 
 
 
 

' Send a 1

xmit1:

  gosub send1

  goto nextbit
 
 
 
 

' Send bits (0 or 1)

send0:

  low rts

  pause 1

  high rts

  return
 
 

send1:

  low dtr

  pause 1

  high dtr

  return
 
 
 
 

' Always reset firecracker first

resetfirecracker:

low rts

low dtr

pause 50  ' reset

high rts

high dtr

pause 50

return
 
 

' Data for house and unit codes

housetbl data $60,$70,$40,$50,$80,$90,$A0,$B0,$E0,$F0,$C0,$D0

      data $00,$10,$20,$30

unittbl data 0,$10,$8,$18,$40,$50,$48,$58