Re: AT commands - Nokia 6210 phone help?

[Kim Wall <kim@xxxxxxxxxxxxxxxxxx>]

stuart Billinghurst wrote:
> A.   When I send the ascii letters A and T out via the com1 from
> HyperTerminal to the phone should the phone respond?

Should do, yes.  If it's not the wrong port, baud rate or handshaking,
try power-cycling the phone.  It sometimes gets confused and stops
responding.

Oh, you need a carriage return after the AT!

You may find RealTerm <http://realterm.sourceforge.net/>
more suitable
to this sort of low-level serial hacking than HyperTerminal.  It'll do
useful things like show you the state of the serial port pins in real
time, and output in hex rather than ASCII.


> B.   If I used a PIC to do the same via a MAX232 chip would the
> output to the phone be identical to the above (i.e. is my testing
> valid?)

I've used a PIC to send a simple ATDnnn 'dial' command to a 6210, to
ring my mobile when the car alarm was set off (a call being less prone
to delay than an SMS, and allowed for custom ringing on the phone I was
using).

I actually got away without using the MAX232 or equivalent - my Nokia
data cable was happy enough with 0-5V on the TXD pin.  I didn't bother
connecting RXD (which presumably *would* need some level conversion).
Your cable may vary.


> D.   Am I heading down the wrong path?

Seems like it should work fine.  As I say, sometimes the phone gets
confused and doesn't respond to serial commands, so it would be worth
including some sort of diagnostic facility (a button to send a test
message when pressed or similar).  In my experience, once it *is*
working, it will continue to do so unless the data cable is disconnected
from the phone, or the phone is switched off.

Also, FWIW, it seems that the 6210 will happily run off a 5V supply
indefinitely (I used one of those USB charging cables to power it off
the 5V regulator supplying the PIC), but the battery will never fully
charge.  Which is probably bad news for the battery.  IIRC, the phone's
current draw levels out at about 50mA, so assuming a mA or two for the
PIC and sensors a car battery should last several weeks.


Hope some of that's of use...

Kim.

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