Post by thread:[PIC:] 12C509 problem

>Is there a difference ( or several differences) >between a 509 OTP and a 509 Eprom? People have reported problems like this in the past, but typically in the reverse direction, I.E. JW->OTP. What is known to happen is that the light coming in the window of a JW part will initialise RAM registers to different states to the OTP parts. It would pay to check through your code to make sure that the RAM registers are being properly initialised by your program. You may have just got away with it in the OTP part, and another one may work differently. -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Alan wrote: > >Is there a difference ( or several differences) > >between a 509 OTP and a 509 Eprom? > > People have reported problems like this in the past, but typically in the > reverse direction, I.E. JW->OTP. > > What is known to happen is that the light coming in the window of > a JW part > will initialise RAM registers to different states to the OTP > parts. I always cover the window so that light never gets in. I learned this may years ago when I was trying to connect to the RS232 port on a PC. Every time I put my hand near it (or over the top of), it would work. Apart from that, you must always pre register the ram variables so that you know what they start up with. In what way is the PIC "not working at all"? Does the oscillator run? Brian. -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

At 12:37 PM 3/1/2004 +0000, you wrote: > >Is there a difference ( or several differences) > >between a 509 OTP and a 509 Eprom? > >People have reported problems like this in the past, but typically in the >reverse direction, I.E. JW->OTP. > >What is known to happen is that the light coming in the window of a JW part >will initialise RAM registers to different states to the OTP parts. It would >pay to check through your code to make sure that the RAM registers are being >properly initialised by your program. You may have just got away with it in >the OTP part, and another one may work differently. As well, if you first programmed it with a non-working program and then attempted to erase and program a working program, you may have a problem, if you protected the memory. On the UV erasable (JW) parts the protect bit is often made deliberately difficult or impossible to erase compared to the rest of the program. This prevents re-use of the part, except as a tie clip or something, so you have remember never to set it. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu