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Subject: Re: recorder schematics (differences)

Re: recorder schematics (differences)

From: Joachim Schiffer <>
Date: Wed, 19 Dec 2001 19:26:11 +0100

> If i manage to define the needed devices in eagle, I try to draw a
> schematic of the things I discovered so far, so that we have a schematic
> of the player and the recorder.

There are only a few parts left to trace :)
The "TM41ST84W" is indeed a realtime clock, which has also built-in
watchdog-functions, and is controlled by I2C Bus at Pins PB7 (SDA)
and PB13 (SCL)

It will take a few days, until i can post the (almost) complete schematic of
the recorder, because i have to define all devices except Opamps and ttl-ics...

Until then, i can post single connections if they were important to analyze
the firmware code...

The most important might be these (i think):
CPU meaning
PB10 serial in (remote control)
PB6 red led
PB8 on button (pulled low if pressed)
PA5 power on hdd
AN6 battery voltage (over FET, switched)
AN2 battery voltage (directly connected over diode)
AN0 must be an output... goes to a voltage divider and then
    to a comparator with 2 or 2,5 volt reference diode...
    if the output of this comparator goes low, the off-switch
    is activated (i think this is used, if the battery gets low,
    to stop the player)
    the reference voltage is also connected to
PB5 Powers on internal power_supply which is connected
    to the external supply... (at this point it's getting dangerous,
    i think... please use at your on risk ;)
    If this supply is powered on, the battery gets loaded.
    If the battery is full, the supply is switched off, and the
    recorder unloy runs from battery.
AN1 is connected to PB 5 (dont know why)
PB4 off button (pulled low if pressed)
    if PB4 is switched to low, the unit will probably switch off,
    too. Also the output of the voltage comparator is connected
    to this pin. (stops playing if power fails)
PB7 SDA (for Micronas and RTC)
PB13 SCL (for Micronas and RTC)
AN11 Buttons UP, F3 (right), F2 (middle), F1 (left)
    /* AN11, AN13: buttons ordered by their voltage
    from low (1,1V?) to high (1,6V?) */

Received on 2001-12-19

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