Hi Franc et al,
first of all my apologies for not being able to reply any earlier to
this thread with an update. My deepest apologies. Meanwhile I got a
spare PCB for the garage door opener which has no need for any
piggyback PCB any longer. Thanks God! The 8748 of the old PCB is still
alive as well. I was able to access its EPROM contents. Sorry that it
took me so long, but getting access to an 8748 adapter for my old ISA
EPROM programming card was a real challenge to me. But thatīs another
story...
Anyway, the new PCB looks very similar to the old one:
front side of the new PCB:
http://img143.imageshack.us/img143/1120/cimg0131kd8.jpg
back side of the new PCB:
http://img68.imageshack.us/img68/4202/cimg0128ms3.jpg
Franc, you already were so kind as to start to track down the logics
of the 16-pin IC a couple of time ago (see text below). I am still
stuck in finding out the exact type of this logic IC. And, believe me,
I have already looked up hundreds of different datasheets at
www.datasheetarchive.com. Hmpf. The manufacturer of the PCB is still
not able (or should I better say willing...) to reveal the exact type
of this IC. But they told me that itīs definitely no PAL. What is
known to me is the following pin assignment:
Pin 1: Output, controls the basis of the transistor which in turn
controls GND of relay no. 3
Pin 2: Output, controls the basis of the transistor which in turn
controls GND of relay no. 2
Pin 3: Output, controls the basis of the transistor which in turn
controls GND of relay no. 1
Pin 4: Output, controls GND pin of the LED
Pin 5: NC
Pin 6: NC
Pin 7: NC
Pin 8: GND
Pin 9: NC
Pin 10: Input, connected to pin DB2 of 8748 ĩC
Pin 11: Input, connected to pin DB1 of 8748 ĩC
Pin 12: Input, connected to pin DB0 of 8748 ĩC
Pin 13: ?
Pin 14: ?
Pin 15: connected to GND
Pin 16: V_cc (+5V)
I hope you, Franc, and/or anyone else here has a good idea of which
logic IC this might be?
Thank you so much in advance.
Joachim
On Sun, 11 Feb 2007 20:37:47 +1100, Franc Zabkar
wrote:
On Sun, 11 Feb 2007 01:03:22 +0100, Joachim Wunder
put finger to keyboard and composed:
On Sat, 10 Feb 2007 10:27:49 +1100, Franc Zabkar
wrote:
On Fri, 09 Feb 2007 13:37:10 +0100, Joachim Wunder
put finger to keyboard and composed:
might the 16-pin IC a I2C maybe? If so, which
ones were commonly used to control an Intel 8748/8749 ?
I just uploaded seperate larger pics of the front and back side of the
PCB:
front side:
http://img184.imageshack.us/img184/3231/cimg0083kj3.jpg
back side:
http://img187.imageshack.us/img187/1555/cimg0084qg6.jpg
I am sorry to not have done that any earlier. On weekends I now have a
little more time to take better pics and start any systematical
diagnostic tests.
There appear to be 8 or so interconnect pins at the RHS of the 16-pin
IC. Can you trace them to the uC's pins? Do they go to the data bus,
ie pins 12 through 19?
As far as I can see Pins 12, 13 and 14 of the microcontroller are
connected to the interconnect pins at the RHS of the 16-pin IC.
Which pins are power and ground?
Pin 8 is V_SS (GND) and Pin 16 is V_DD (+5V) as far as I measured on
the 16-pin IC.
What is the IC
to the right of the relays?
Thatīs a PHILIPS CNY17-4 Optocoupler.
Which chip/component drives the relay
coils?
Thatīs actually a BC237B transistor each. They are hidden below the
piggyback PCB, unfortunately.
- Franc Zabkar
Thanks
Joachim
AFAICT, the 16-pin IC, if the piggyback PCB faithfully mimics the
pinout, has at least three outputs at pins 1,2,3, each of which drives
the base of a relay driver transistor. Each pin has a pullup resistor
to Vcc, so I suspect that the outputs may be open collector.
Since pins 10,11,12,13 of the IC are connected to the uC's data bus, I
suspect that they may be inputs. If so, then I believe that these
inputs would need to be latched. The fact that there is a "VOH" on the
body of the chip suggests that it might be programmed, in which case
it could be a PAL.
- Franc Zabkar