From: Fred <speed-up_at_fr.st>
Date: Sun, 2 Feb 2003 23:16:58 +0100

I could just did the measures Uwe wanted me to, and I'd like to post them in
the newsgroup, as everybody should see it ...

So, to get Archos FM voltage you need to put off the pannel situation at the
bottom of the device (the top one is a fake ;), to discover 20 pins. The
zero (masse in french) is on pin 10, and the reference voltage (stable,
whatever comes up) seems to be between pins 10 and 1, constantly 3.2V
Pins 2 to 9 seem not to deliver voltage, may be comunication bus or
something like that. The 10~11 voltage is constantly 0V, but when the HDD is
coming up the value is raising to 4.5V, and comming back to zero when the
disk turns down (no matter if the backlight is on or not). The 10~12 voltage
seems to be an average value, maybe constant, of 3.0V. My short study shows
that the voltage between pins 10 and 13 figures out the real voltage, in
real time. After a complete charging, it's about 3.2V. Then, it comes down,
and after about an hour of playing, the voltage is about 2.7V when booting
the device, and 2.9V in playing mode (3.1~3.0 when nothing is being played).
It changes a bit across time, when the HDD comes up for instance, it can
loose 0.1V, but generally keeps stable. The other pins, 14 and next, seem
not to be very usefull. I found pin 14 being about 3.2~3.1 (I can't really
remeber, but it didn't changed across time), and another pin showing 1.5V,
another handling around 0.2~0.5 ... so I think I've found the real pin, and
it's number 13.

I hope those infos will be usefull for further Recorder FM developement, and
can only encourage FM users who would do further measures, during a
full-decharge cycle (I don't really got time for this, and I don't use my
device the whole day ...).

Fred

PS : Here is a part of the email Uwe Freese sent me, you should read it in
order to know what exactly to do.

=====================================================

First of all: Linus is right, we need someone with an FM Recorder who
opens it and looks how it works.

Until then, I only can guess.

F> The AN6 is about 204 when the device has been full charged, but is
viewable
F> only when the backlight and/or the HDD are running.

Is it enough that backlight is on? Or has the HDD also be on to have AN6 >
0?

F> When this is not the
F> case, the AN6 register goes down to 0 and ... the AN0 register seems to
be
F> showing the right voltage, as it comes from zero to 3FF when the AN6
F> register is coming down to zero. I think you should use AN6 when it's >0
and
F> if not, check the AN0 register.

Please have a look at firmware/drivers/adc.h. It shows how the ANx are
used at the recorder. I don't think that AN0 can be used.

F> Another thing : even when it's been fully charged, the battery is charged
at
F> 40% when I start the Rockbox rom : this needs to be fixed too.

That could mean that the FM has an other "battery scale factor" (how the
voltage is calculated out of AN6). But for knowing the right one, we
have to open the device.

Run the attached firmware. ATTENTION: I set the shutdown voltages to 0
so that it doesn't shut down. That means that it never shuts down, even
if the battery is empty. That will destroy the battery if you leave
Rockbox on for too much time.

Can you open the battery flap? Do you have a voltage meter? Can you
please make measure pairs

(value of AN6 when backlight on) and (voltage of battery)

The charger should be disconnected.
If AN6 really is the batt voltage, I need let's say five value pairs to
guess the battery scale factor. Let the battery be differently full. Run
the Archos firmware to make your battery more empty.

=====================================================

Schau doch bitte mal nach, ob man die Batterieklappe öffnen kann. Wenn
du dann noch (vielleicht zusammen mit einem Freund, der ein Multimeter
hat) ein paar dieser Messwert-Paare messen kannst, würde es weiterhelfen.

Wie gesagt, ohne diese Werte kann ich momentan weiter nichts machen.

=====================================================
Received on 2003-02-03