rev d hangup
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Posts: 46,084
Hi to all...
I have two rev d stamps. One has its board populated with my project,
the other is as it was new. The program code has worked as designed
for several weeks (automotive application). Once the outside temp
began to fall I have discovered the stamp acts like its hung. The 5v
regulator is up, and on occasion there is 5v on the reset pin (pin 4
of the large chip), but sometimes I find it near zero. The center pin
of the programming hookup normally has a 2.5v pulse. When I find it
in that mode I know it will work ok. When I suspect its hung, there
is either zero on this center pin or 5v.
In the course of fooling around, I have discovered that if I probe
pin 17 (the larger chip) everything stops. The only recourse is total
power down. I have an external reset ckt on my side of the board, it
is a pair of pnp xtrs that essentially interrupt the supply when the
base of the second goes low. On the bench this works. In the car it
appears to work - but when this puppy is hung, the onboard reset ckt
won't bring it back to life. Completly unhooking it and waiting will
usually reinstate the circuit but for a short time only.
My question... do I have defective rev d's here or is this circuit
normally unstable below 30 degrees?
Thanks...
I have two rev d stamps. One has its board populated with my project,
the other is as it was new. The program code has worked as designed
for several weeks (automotive application). Once the outside temp
began to fall I have discovered the stamp acts like its hung. The 5v
regulator is up, and on occasion there is 5v on the reset pin (pin 4
of the large chip), but sometimes I find it near zero. The center pin
of the programming hookup normally has a 2.5v pulse. When I find it
in that mode I know it will work ok. When I suspect its hung, there
is either zero on this center pin or 5v.
In the course of fooling around, I have discovered that if I probe
pin 17 (the larger chip) everything stops. The only recourse is total
power down. I have an external reset ckt on my side of the board, it
is a pair of pnp xtrs that essentially interrupt the supply when the
base of the second goes low. On the bench this works. In the car it
appears to work - but when this puppy is hung, the onboard reset ckt
won't bring it back to life. Completly unhooking it and waiting will
usually reinstate the circuit but for a short time only.
My question... do I have defective rev d's here or is this circuit
normally unstable below 30 degrees?
Thanks...
Comments
opposed to the commercial temp range of the other stamps.
Original Message
From: "base_profile
> Hi to all...
>
> I have two rev d stamps. One has its board populated with my project,
> the other is as it was new. The program code has worked as designed
> for several weeks (automotive application). Once the outside temp
> began to fall I have discovered the stamp acts like its hung. The 5v
> regulator is up, and on occasion there is 5v on the reset pin (pin 4
> of the large chip), but sometimes I find it near zero. The center pin
> of the programming hookup normally has a 2.5v pulse. When I find it
> in that mode I know it will work ok. When I suspect its hung, there
> is either zero on this center pin or 5v.
>
> In the course of fooling around, I have discovered that if I probe
> pin 17 (the larger chip) everything stops. The only recourse is total
> power down. I have an external reset ckt on my side of the board, it
> is a pair of pnp xtrs that essentially interrupt the supply when the
> base of the second goes low. On the bench this works. In the car it
> appears to work - but when this puppy is hung, the onboard reset ckt
> won't bring it back to life. Completly unhooking it and waiting will
> usually reinstate the circuit but for a short time only.
>
> My question... do I have defective rev d's here or is this circuit
> normally unstable below 30 degrees?
>
> Thanks...