Determine type of unknown 8-pin microcontroller

Thread Starter

dfka

Joined Sep 8, 2017
7
I bought some tubes containing microcontrollers and a couple of populated boards which should use the same microcontrollers, from a company that had gone bankrupt.

The microcontrollers are unnamed, but I had hoped that they were ATtiny or something similar.


However, the populated boards do not seem to match with them being ATtiny.

The boards are very basic, just two buttons which makes a LED light for 5 seconds.


The microcontrollers have 8 pins, length is about 5 mm and width (without legs) are 4 mm.
1.27 mm between the pins.


Pin-1: 3.3V, with a cap to gnd.

Pin-2: Output to LED-driver.

Pin-3: Input, is pulled to gnd when clicking on the first button.

Pin-4: Pulled to gnd with a 10K Ohm resistor.

Pin-5: NC.

Pin-6: NC.

Pin-7: Input, is pulled to gnd when clicking on the second button.

Pin-8: Gnd.


ATtiny25/ATtiny45/ATtiny85 have Vcc on pin-8, which is ground for my microcontrollers.

PICAXE seems to have In on Pin 2 which is output, and Out on pin-7 which is input.


What other microcontrollers should I take a look at?


Thanks
 

AlbertHall

Joined Jun 4, 2014
12,160
Microchip. One I looked at, PIC12F1571, has the power connected to the right pins, would work on 3.3V.
Pin 4 is, amongst other things, the reset input and would be connected to Vcc but that can be disabled.
 

Thread Starter

dfka

Joined Sep 8, 2017
7
Thank you so much for your input, it’s really appreciated.


I’ve gone through the data sheet, however, I can’t seem to understand why they would pull pin 4 to gnd, while leaving pin 5 & 6 floating.

Pin 4 is GPIO, Programming Voltage, Timer1 input, and ‘Master clean with internal pull up’.
GPIO and programming voltage does not seem to be relevant.
The data sheet points out that while pulling MCLR to gnd “the device is held in Reset”.
And that MCLR can be disabled, like you mention.


Could it be related to timer1 gate input (T1G) and/or a counter?
The LED-driver seems to be driven in a repeated pattern.



The boards look like showcase/demo boards for the microcontroller, so they are pretty minimalistic.
And I don-t think that they would add any unneeded components.



I found a board in another lot, from the same company, which seems to be a prototype.
The microcontroller is also unnamed, however, pin-4 is pulled high with a 47K ohm resistor.
It’s not guaranteed that it’s the same microcontroller.
 

AlbertHall

Joined Jun 4, 2014
12,160
Could it be related to timer1 gate input (T1G) and/or a counter?
The LED-driver seems to be driven in a repeated pattern.
The PIC has an internal clock oscillator which can drive the timers as needed. It doesn't need the external input for that.
 

AlbertHall

Joined Jun 4, 2014
12,160
The PIC has an internal clock oscillator which can drive the timers as needed. It doesn't need the external input for that.
As a general rule, unused inputs should not be left floating. The unused pins on that PIC can be set as outputs to avoid that problem but pin 4 is input only hence, maybe the reason for the resistor to ground.
 

Thread Starter

dfka

Joined Sep 8, 2017
7
Oh, I’m so sorry, I was a bit too fast when reading the data sheet, so I read it as General purpose I/O.
That makes sense if the two others are I/O, and pin 4 is input-only.


So, I’m guessing that the next step for me is getting a PICkit 3.


Thanks so much for your help.
 

Thread Starter

dfka

Joined Sep 8, 2017
7
Yes, of course.

I knew from the start when I bought the lot that the chance of getting the microcontrollers to use would be pretty low.


It’s more a learning experience for me.
 
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