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Step 9Put it together.
I am eliding some key parts of this 'ible: all of these circuits have to be put together, tested, debugged on the breadboard, then hardwired to real circuit boards and placed in the body of the phone itself. I will simply offer a few lessons hard learned:
1. when something doesn't work, apply Occam's Razor- it's probably not an elaborate error in the inner workings of your microchip.
2. Just because the component schematic says that a connection is hardwired closed does not mean you can't fry it open.
3. prepare your repeatable tests before you go far in putting things together. You'll need them. It won't work the first time. I know you think it will. It won't. Be ready to test, and re-test.
Before you seal the phone up, though, don't forget to program the microchip.
I've included my source code (in ugly pBasic) with lots of comments. The logic is simple, but there are a few tricky parts, so here is the outline:
Loop until someone triggers the PIR. Within the initial loop, generate pseudo-random numbers. Since you cannot predict the time a visitor will come by, it is random enough for government work.
When a visitor passes (detected on your PIR) randomly select an area code.
Then dial each digit of the area code, keeping the button "pressed" for long enough to dial it, and with enough space in between each "press" so as not to interfere with the others.
Dial the randomly generated number.
Enter the ring subroutine. This is the tricky part. I used software to create the right ring pattern as described before, but I also had to include a sub-loop that stopped and checked for the receiver's being off the hook many times within each ring- if you don't, a visitor will pick up the phone, but it won't know to stop ringing.
There is also some highly specific code dedicated to dialing from the specific phone system- dialing prefixes and billing suffixes (TAN, they called it). These will be specific to your system.
Now that the phone is hacked, put it somewhere and make connections.
1. when something doesn't work, apply Occam's Razor- it's probably not an elaborate error in the inner workings of your microchip.
2. Just because the component schematic says that a connection is hardwired closed does not mean you can't fry it open.
3. prepare your repeatable tests before you go far in putting things together. You'll need them. It won't work the first time. I know you think it will. It won't. Be ready to test, and re-test.
Before you seal the phone up, though, don't forget to program the microchip.
I've included my source code (in ugly pBasic) with lots of comments. The logic is simple, but there are a few tricky parts, so here is the outline:
Loop until someone triggers the PIR. Within the initial loop, generate pseudo-random numbers. Since you cannot predict the time a visitor will come by, it is random enough for government work.
When a visitor passes (detected on your PIR) randomly select an area code.
Then dial each digit of the area code, keeping the button "pressed" for long enough to dial it, and with enough space in between each "press" so as not to interfere with the others.
Dial the randomly generated number.
Enter the ring subroutine. This is the tricky part. I used software to create the right ring pattern as described before, but I also had to include a sub-loop that stopped and checked for the receiver's being off the hook many times within each ring- if you don't, a visitor will pick up the phone, but it won't know to stop ringing.
There is also some highly specific code dedicated to dialing from the specific phone system- dialing prefixes and billing suffixes (TAN, they called it). These will be specific to your system.
Now that the phone is hacked, put it somewhere and make connections.
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