Homemade Serial to Nokia MBus Interface on a PCB, without
using Zener diodes.
|U1||78L05, 5 voltage regulator. Not the 7805, that will be too big for this project.|
|U3||MAX232 IC, available in Australia from Jaycar or Dick Smith. Easy to get, every proper electronics shop in the world should carry this IC.|
|D1,D2||Just your standard 1N4148 signal diodes.|
|C1||Can be anything near 100uf.|
Just use anything between 1uf to 50uf, the voltage regulator won't care.
|C3 to C6||10uf, can be 4.7uf or 6.8uf as long as these 4 capacitors, are the same value.|
|R1, R2||10 KOhm resistors|
|R3, R4||4.7 KOhm resistors|
|Q1, Q2||BC547 transistors, BC548, BC549 will also work.|
Just holes in the PCB for attaching the wires. Connections are
PS: for those wanting a cheap serial cable, don't cut the cord
off a old microsoft mouse like I did. Microsoft mice don't receive
data from the computer, and therefore only have four wires in the
cable. Useless for this project. Find an old Genius mouse they have
the neccessary number of wires.
Mbus connection to phone, Pin 1 on J2 goes to the mbus connection on the phone.
Pin2 on J1 goes to ground line on phone.
Now for the PCB tracks, you may notice that the tracks are slightly different to ones in the image above. I have just touched up some areas that the PCB software stuffed up. Also I have flipped the image ready for PCB printing.
Which looks like this after solidering everything.
Ah! but one final thing. How do you attach the wires onto the phone?
Simple! just get some paperclips and tape.
Tape them together about 5mm apart leaving only a small amount of metal uncovered. This is the cheapest way other than buying a hands free kit and pulling it to bits.
This interface works with any of these phones above.
Below: another 3210 connection pinout.
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