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View Full Version : Very sick propeller chip. Update: All better :)



Cluso99
10-21-2011, 05:57 AM
Today I hurt my first prop chip. I am very disappointed it didn't completely survive a hit of 5V on the Gnd pin and Gnd on P24. At least thats what I think I did. There was the obligatory tell-tale sign something was wrong... you know that smell !!!

There have been numerous times I have connected 3v3 & Gnd around the wrong way, and times I have connected 5V instead of 3v3, shorted inputs and outputs, etc, and all these props somehow survived.

However, this one is quite sick. It downloads and programs the eeprom correctly, and then it starts to display data to the serial port. Just when you think all is well, it has a fit and resets part way through the message, and continues to do this. And no, it's not the reset issue with the FT chip.

You know, you really get lulled into a false sense of security that these prop chips are indestructable... Well, not always.

MagIO2
10-21-2011, 07:25 AM
Maybe this is exactly the "illness" you need to build Number 5. (Hope this also was the original name of the robot in "Short circuit" ;o)

Ale
10-21-2011, 09:23 AM
Cluso, knowing that both GNDs are connected together through a low-ohm trace... I would guess that it is really toasted.

Toby Seckshund
10-21-2011, 12:39 PM
I did do a 3.3 Volts the wrong way around and a 9 Volts the right way around. The reverse case survived but did show some glitching on the "turbulence" word on Linus's demo.

***'s law states that the one that got toasted with 9 V couldn't be that one, but was the one Prop that seemed quite happy with 14+MHz xtals.

The blown chip is now a prime candidate for an internal inspection. Wood chisels at the ready!

Oldbitcollector (Jeff)
10-21-2011, 06:16 PM
5,842 posts and this is the first time you manage to kill a Propeller? :)

It's a testament to the robustness of the chip. I've been smacking them around since 2006 and I still haven't managed to kill one. I have taken out a few boards.. :)

OBC

Cluso99
10-21-2011, 08:27 PM
5,842 posts and this is the first time you manage to kill a Propeller? :)

It's a testament to the robustness of the chip. I've been smacking them around since 2006 and I still haven't managed to kill one. I have taken out a few boards.. :)

OBC
I have built 100's of prop boards but these do not really count because they are proven circuits.

However, I have built lots of boards for experiments including both hardware and software. IIRC I started in early 2008. So, this is the first prop that I fried.

I did not include the prop I fried a few weeks ago while I was experimenting with my new IR soldering station - the chip got cooked (literally by heat, and left a bubble on the chip and that burning smell too). I have not even bothered (at least yet) to see if the prop works. I haven't taken out any boards yet... now where is that timber (touch-wood)???

Cluso99
10-22-2011, 12:21 AM
Great news. I found out that what I did was solder the USB plug to the wrong footprint (my pcb has dual footprints for the plug and socket). I had previously thought I plugged the pcb into the wrong connections on my prop pcb.

So, what happened was that I reversed 5V and Gnd. I have now replaced my onboard 3v3 regulator and all is well! Prop is running again ;)

frank freedman
10-22-2011, 06:45 AM
Great news. I found out that what I did was solder the USB plug to the wrong footprint (my pcb has dual footprints for the plug and socket). I had previously thought I plugged the pcb into the wrong connections on my prop pcb.

So, what happened was that I reversed 5V and Gnd. I have now replaced my onboard 3v3 regulator and all is well! Prop is running again ;)

Good news, better go out and buy that lottery ticket while the luck holds..

Frank

bsnut
10-22-2011, 07:36 AM
If, I Blue Smoke the first Propeller chip I will go out and buy that lottery ticket while the luck holds. Because, I won't be doing it again.

Toby Seckshund
10-22-2011, 08:33 AM
Nah, it had nothing to do with any USB connections!

The wood chisel threat always works.

Ahle2
10-22-2011, 11:21 AM
I have got a lot of Propeller chips, but only one that is not 100% functional.
The video generator in cog 0 has decided to not publically show any pixels anymore. (I am pretty sure it has got a lot of pixels stored up for its own needs though)

/Johannes

Cluso99
10-23-2011, 04:41 AM
While I was at school (late 60's) I used to buy faulty 74xxx TTL chips from a UK supplier. These chips failed manufacturing specs and were pot luck about what worked. For instance, a 7400 quad Nand gate may have 3 gates fully functional and the fourth could be dependant on the others input (like some sort of internal short). They sold for about 1-2 pounds each.

Toby Seckshund
10-23-2011, 09:13 AM
I didn't get into TTL until the early 70s. I made an addressable counter thing that would allow me to set or reset bits in a 2101 (i think) SRAM, it was 1K x 1 and gave me and my father a 32 x 32 matrix that we fed with a very crude weather sattelite pic. It was a bit better (technically) than the windscreen wiper motor and electro-sensitive paper, iodine and starch if I remember correctly.

Most of all the stuff back then was reclaims off of scrap boards and so had some bits not working correctly, I still have that habit now!

Leon
10-23-2011, 09:23 AM
While I was at school (late 60's) I used to buy faulty 74xxx TTL chips from a UK supplier. These chips failed manufacturing specs and were pot luck about what worked. For instance, a 7400 quad Nand gate may have 3 gates fully functional and the fourth could be dependant on the others input (like some sort of internal short). They sold for about 1-2 pounds each.

I bought TTL chips from what was probably the same supplier - called Bi-Pak or Bi-PrePak, or something like that. I think there were two companies. Before TTL came along, I played about with RTL chips - 3V supply, lots of current and very poor noise immunity. I started building a frequency counter using them, and made a couple of the counter/display stages, using four torch bulbs to display the count for each decade in BCD. I lost interest in it when TTL came along.

Toby Seckshund
10-23-2011, 10:03 AM
Most of the TTL stuff I got hold of had 54xxx numbers because of where they came from (officially the boards were suposed to have been destroyed) :-)