Re: bike computer to PC interface
- From: "petrus bitbyter" <pieterkraltlaatditweg@xxxxxxxxxxxxxxxxx>
- Date: Wed, 7 Mar 2007 23:53:53 +0100
<pete_tomson@xxxxxxxxxxx> schreef in bericht
news:1173287192.402131.180590@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi All - I found this newsgroup and was wondering if anyone could help
me.
I'd like to connect a magnetic sensor (bicycle computer) directly to
my computer through one of the ports without a power supply.
Basically the reed switch will have a current induced in it so I'm
thinking I'd ideally like the circuit to be passive with minimal
external circuitry.
I have a pic of a basic circuit I found but don't know how it works
and I don't know how to post it. Basically it has a connection to pin
4 through a 4.7kohm resistor a direct connection to pin 6 and a ground
through pin 20.
If you tell me how to post a pic I can show the diagram.
Can anyone make suggestions about circuit design - can I feed the
wires directly into my parallel/serial port?
I'm also trying to write a program in VB6 to read the input, but not
having much luck.
I'd really appreciate any help anyone could give me.
Thanks
Pete
For the bike computers I'm aware of they tie a magnet to the wheel and some
sensor to the frame. That sensor can be a coil or a Hall type sensor but I
never saw a reed switch so far. Nevertheless, for a simple solution I'd tie
a strong magnet to the wheel and a reed switch to the frame. You may heve to
do some experiments to find a reliable combination, but once you have a
working reed switch, you can count pulses through a serial- or parallel port
very easily.
D0(2)------+
|
.-.
3k3 | |
| |
'-'
|
PE(12)-----+
|
\ o
\
\.
o
|
GND(18)----+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
Above an example to use the parallel port. Drive D0 (pin 2 of the pp
connector) high and you can read the state of the switch through PE (paper
empty pin 12).
petrus bitbyter
.
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