An update on my project:
I finally got it working. I learned two important things:
1) Siemens phones shuts automatically down if the voltage is too high: > ~4v
2) In order for a Siemens C65 to accept data, the CTS (pin 5) need to be shorted to ground.
This is my current setup:
View attachment 71051
Still, there is a lot of work to be done:'
* Move the logic from PicAxe to pure PIC-code
* Make the trigger logic. I believe I will use a magnetic switch of some kind.
* Make logic so that if I accept the call from the alarmsystem, I trigger the sound alarm. If I reject, nothing happens.
* Interface the keyboard of the mobile phone. This is in order to be able to switch it on, and to press a specific button to confirm that I indeed want to switch it on. I have disabled the pin-code check in the startup.
* Transform voltage from 6V to 3.7V for the mobile. The phone needs 3.7V, and I tried to run it from 3 x AAA batteries (4.5V) with two diodes in between to lower the voltage. However, when the phone started to draw power during startup, it instantly shut down. Alkaline batteries drops to much under load! Solution: Use a voltage regulator to lover the voltage from 6V to 3.7V. My estimates are that 6V time 0.7 A = 4,2 W - efficiency loss, should be enough to run it without any fuss. If that is not enough, I will have to add more batteries or shift to C/D -cells
* Make sure that the entire system, in its idle state, can run for minimum 4 years without battery change. Of course, if triggered this will affect lifetime significantly.
Finally, I have some questions for all the smart people out there:
* What is the best way to transform 6V battery power to 3.7V constant power, with minimal efficiency loss.
* What software do you use for schematics? I have tries some, but don't feel very comfortable with them?! Is there a "Paint shop pro" for electronics design? That is cheap and good
best regards
JF
