Ian Bell wrote:> Alistair George wrote: > >> Re HEF40106BT been there, tried that does not work in our use, which as >> a very high gain oscillator. >> > > You are using a hex schmitt trigger as a high gain oscillator? > > IanYes, in the original National app notes shows a schmitt trigger as an oscillator. Variations between manufacturers have largely made that form of use redundant. PS thanks to others for continuing this thread to the enlightenment of myself and others on the use of, and alternatives to the original 8051 series of uP. Al.
8051 dead or what?
Started by ●June 23, 2006
Reply by ●June 24, 20062006-06-24
Reply by ●June 25, 20062006-06-25
Alistair George wrote:> Ian Bell wrote: > >> Alistair George wrote: >> >>> Re HEF40106BT been there, tried that does not work in our use, which as >>> a very high gain oscillator. >>> >> >> You are using a hex schmitt trigger as a high gain oscillator? >> >> Ian > > Yes, in the original National app notes shows a schmitt trigger as an > oscillator. Variations between manufacturers have largely made that form > of use redundant.This is curious - I take it you mean something other than the standard, widely used 2 terminal RC Schmitt oscillator ( or the 3 terminal oscillator, which is more acurate but needs 3 gates of a 40106 ) ? Do you have a URL of such a configuration ? -jg
Reply by ●June 25, 20062006-06-25
Jim Granville wrote:> Alistair George wrote: > >> Ian Bell wrote: >> >>> Alistair George wrote: >>> >>>> Re HEF40106BT been there, tried that does not work in our use, which as >>>> a very high gain oscillator. >>>> >>> >>> You are using a hex schmitt trigger as a high gain oscillator? >>> >>> Ian >> >> Yes, in the original National app notes shows a schmitt trigger as an >> oscillator. Variations between manufacturers have largely made that >> form of use redundant. > > This is curious - I take it you mean something other than the > standard, widely used 2 terminal RC Schmitt oscillator ( or the 3 > terminal oscillator, which is more acurate but needs 3 gates of a 40106 ) ? > > Do you have a URL of such a configuration ? > > -jg > >No Jim, the former as you suggest but in our app it uses a 3m3 feedback r and a special capacitor. Spreads between i/c of the same maker were acceptable, but not between supposed replacement alternatives. In hindsight, I should have used a comparator for the job. Al.
Reply by ●June 25, 20062006-06-25
Jim as an aside, I know you have your own hardware emulators, but have you used the DS2250? I built a bunch of these emulators up 8 years ago, when they worked perfectly, now cant get them to work, despite various RS232 cables, baud rates, DOS (not XP) and so on - keep getting coms errors, but can use dallas KIT5k to upload kernal. Al.
Reply by ●June 25, 20062006-06-25
Jim Granville wrote:> Alistair George wrote: > >> Ian Bell wrote: >> >>> Alistair George wrote: >>> >>>> Re HEF40106BT been there, tried that does not work in our use, which as >>>> a very high gain oscillator. >>>> >>> >>> You are using a hex schmitt trigger as a high gain oscillator? >>> >>> Ian >> >> Yes, in the original National app notes shows a schmitt trigger as an >> oscillator. Variations between manufacturers have largely made that form >> of use redundant. > > This is curious - I take it you mean something other than the > standard, widely used 2 terminal RC Schmitt oscillator ( or the 3 > terminal oscillator, which is more acurate but needs 3 gates of a 40106 ) > ? >I think he means in a crystal oscillator - ISTR this was a common way of generating a microprocessor clock in the 80s but even then it was known to be unreliable due to using a digital device in an analog mode. Ian
Reply by ●June 25, 20062006-06-25
On Sun, 25 Jun 2006 10:52:12 +0100, the renowned Ian Bell <ruffrecords@yahoo.com> wrote:>Jim Granville wrote: > >> Alistair George wrote: >> >>> Ian Bell wrote: >>> >>>> Alistair George wrote: >>>> >>>>> Re HEF40106BT been there, tried that does not work in our use, which as >>>>> a very high gain oscillator. >>>>> >>>> >>>> You are using a hex schmitt trigger as a high gain oscillator? >>>> >>>> Ian >>> >>> Yes, in the original National app notes shows a schmitt trigger as an >>> oscillator. Variations between manufacturers have largely made that form >>> of use redundant. >> >> This is curious - I take it you mean something other than the >> standard, widely used 2 terminal RC Schmitt oscillator ( or the 3 >> terminal oscillator, which is more acurate but needs 3 gates of a 40106 ) >> ? >> > >I think he means in a crystal oscillator - ISTR this was a common way of >generating a microprocessor clock in the 80s but even then it was known to >be unreliable due to using a digital device in an analog mode. > >IanIIRC, the 8048/8749 etc. NMOS microcontrollers used a ST in a Pierce oscillator configuration. IIRC it was supposed to start up in RC mode @ 50kHz or so and then transition to oscillating at the crystal frequency. But there are potential problems (it might not make that transition depending on parameters) and that configuration isn't seen much these days. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Reply by ●June 26, 20062006-06-26
Alistair George wrote:> Jim as an aside, I know you have your own hardware emulators, but have > you used the DS2250? I built a bunch of these emulators up 8 years ago, > when they worked perfectly, now cant get them to work, despite various > RS232 cables, baud rates, DOS (not XP) and so on - keep getting coms > errors, but can use dallas KIT5k to upload kernal. > Al.Fixed it was a pot puri of various things from a defective coms cable (which I'd checked) Windows sometimes doing coms reliably, and other times not. Whew that was tricky! Al.