Yes, I almost killed my brand new BS2pe

Not braindead but paralyzed.

I should test some communication between one master BS2 and another BS2 + the Pe.
The master was safe on the BOE, the other two was placed on a different breadboard next by.
The plan was that the other BS2Pe and BS2 should get their power from Vdd on the BOE, from the connectors ontop of the breadboard.
Due to bad luck and aging eyes I put the plus wire into Vin instead of Vdd, the result was 8,2 V into the two microcontrollers Vcc inputs.
The BS2 didnt seem to be harmed but the Pe ran for a moment without problem until it got stuck and also real hot. But no smoke.

After cutting the power real fast and later connect to normal 5V the BS2 seems to be OK, but the Pe still won't work.

When testing later I found out that the controller can receive software and also run program but can no longer control the PINs.

Setting PIN 0-15 LOW result all pins low except for PIN 7, 11,12 and 15 who remains high.
Setting PIN 0-15 HIGH result that all pins except P10 goes high.

But I suspect several of the others don't behave as they should because I could no longer receive from Master BS2 even I changed from P7 to P8.

So how much over-voltage can be fed into Vcc before it get damaged and is it true that a green BS2 can accept more voltage than the red Pe?


  • Mike GreenMike Green Posts: 23,023
    edited 2017-11-16 (10:34 PM)
    The Vin pin goes into the voltage regulator for the module (BS2 or BS2pe) and that can easily handle up to 12V. The voltage regulator has no real heatsink, so it will get quite hot if you try to draw more than maybe 50mA with Vin over about 7.5V. It's safe even if it gets hot. Putting more than about 7.5V into Vdd or any of the I/O pins can destroy the microcontroller chip. Sometimes one or more I/O pins will go first.

    Usually the datasheet for a device will have an "Absolute Maximum" rating for the power supply voltage and/or voltage on an I/O pin.
  • Mike Green wrote: »
    Putting more than about 7.5V into Vdd or any of the I/O pins can destroy the microcontroller chip. Sometimes one or more I/O pins will go first.

    Yes, most of the I/O pins are destroyed. Seems like one pin, that was connected to a serial lcd display did survive, as the display still works.
    So now I have a brand new BS2pe with 8 slots and SPRAM and one single I/O pin. Could easily been much worse!

  • Moskog

    Have a source with a bunch of new old stock 2E's for $35 each.

    That's how he has them listed. '2E'. They are 24 pin and red so they are probably 2PE's.

    PM me if you if it will help.

  • microcontrolleruser: Thanks but it won't be necessary, I used another one from another project, for the testing I was doing. And the testing itself goes on re-writing some old BS2pe code into BS2 code, taking adventage of using DS1302 's 31 Bytes of battery-supported RAM instead of -pe's 128 Bytes of SPRAM.
    Code that was overkill for the BS2pe but will be almost kill for the BS2.

    BS2e is red, maybe BS2pe is more purple, so your friends stamps are probably BS2e I guess.

  • Good. Glad it worked out.

    The P24 P40 and PX are more what we lean towards.

    Will look up at E and PE in Stamp Reference again.
  • Murderer !!! Seems like you escaped with minimal damage.
  • I would suggest putting a voltage regulator on each BS2/BS2Pe etc.
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