Post by thread:[PIC]: logic gate speeds

The maximum clock speed I understand that a PIC can count at is 50 MHz - correct? I want to count at higher frequencies - up to 500 MHz and I'm looking to use a logic counter to divide 500 by 16 and give an input frequency into the PIC of 500/16 = 31.25 MHz. There's a 7400 series chip, the 74F161 that divides by 16 but the max i/p frequency is 100 MHz. Are there any 7400 series other than F that can go faster or any equivalents that y'all know of? Can anyone point me to a counter, ideally pre-settable and with accessible (to read) outputs, that could take a clock input for counting faster than 100 MHz and divide by 16? Ted Mawson spam_OUTPICmanTakeThisOuTportfoliopm.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I think ECL is the logic family you want. /\/\/\/*=Martin ----- Original Message ----- From: "Ted Mawson" <.....PICmanKILLspam@spam@PORTFOLIOPM.COM> To: <PICLISTKILLspamMITVMA.MIT.EDU> Sent: Monday, February 18, 2002 12:13 PM Subject: [PIC]: logic gate speeds > The maximum clock speed I understand that a PIC can count at is 50 MHz - correct? > > I want to count at higher frequencies - up to 500 MHz and I'm looking to use a logic counter to divide 500 by 16 and give an input frequency into the PIC of 500/16 = 31.25 MHz. > > There's a 7400 series chip, the 74F161 that divides by 16 but the max i/p frequency is 100 MHz. Are there any 7400 series other than F that can go faster or any equivalents that y'all know of? > > Can anyone point me to a counter, ideally pre-settable and with accessible (to read) outputs, that could take a clock input for counting faster than 100 MHz and divide by 16? > > Ted Mawson > .....PICmanKILLspam.....portfoliopm.com > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On 18-Feb-02 Ted Mawson wrote: > The maximum clock speed I understand that a PIC can count at is 50 MHz - > correct? > > I want to count at higher frequencies - up to 500 MHz and I'm looking to use > a logic counter to divide 500 by 16 and give an input frequency into the PIC > of 500/16 = 31.25 MHz. > > There's a 7400 series chip, the 74F161 that divides by 16 but the max i/p > frequency is 100 MHz. Are there any 7400 series other than F that can go > faster or any equivalents that y'all know of? > > Can anyone point me to a counter, ideally pre-settable and with accessible > (to read) outputs, that could take a clock input for counting faster than 100 > MHz and divide by 16? Google search for "VHF Prescaler" found me at http://www.qsl.net/om3cph/vhf_uhf.html which has a 1.3Ghz freq counter based on 16F84 Maybe you could try google next time for yourself ? Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 12:13 PM 2/18/02 -0500, you wrote: >Can anyone point me to a counter, ideally pre-settable and with accessible >(to read) outputs, that could take a clock input for counting faster than >100 MHz and divide by 16? If you just want a prescaler, have a look at NEC's MMIC prescaler offerings. They will work down as far as 100MHz or so, and up into the GHz. If you need outputs, have a look at OnSemi's various ECL offerings. More expensive (you can get them from Newark) and you may have level translation issues. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" EraseMEspeffspam_OUTTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Peter, I've done extensive prior searches on Google. Google is my standard search engine, it's in my favorites and is number 1 on my links bar; I'm not someone who asks on this list before doing my own research if that was your concern? The Frequency counter you pointed to uses a prescaler which works OK but means you lose the lowest 8 bits of binary resolution = 2560 kHz steps in counting on /256 at a gate time of 0.1 secs. Spehro and Martin's suggestions to search for 'ECL' yeilded (on Google) the On-Semi device MC10E016 that counts at 700 MHz min and 900 Typical : ) This also has Q outputs that can be read after the count has happened. Thanks to all for your input. Ted Mawson {Original Message removed}

On Mon, 18 Feb 2002, Peter Onion wrote: {Quote hidden}> On 18-Feb-02 Ted Mawson wrote: > > The maximum clock speed I understand that a PIC can count at is 50 MHz - > > correct? > > > > I want to count at higher frequencies - up to 500 MHz and I'm looking to use > > a logic counter to divide 500 by 16 and give an input frequency into the PIC > > of 500/16 = 31.25 MHz. > > > > There's a 7400 series chip, the 74F161 that divides by 16 but the max i/p > > frequency is 100 MHz. Are there any 7400 series other than F that can go > > faster or any equivalents that y'all know of? > > > > Can anyone point me to a counter, ideally pre-settable and with accessible > > (to read) outputs, that could take a clock input for counting faster than 100 > > MHz and divide by 16? > > > Google search for "VHF Prescaler" found me at > http://www.qsl.net/om3cph/vhf_uhf.html > > which has a 1.3Ghz freq counter based on 16F84 > > Maybe you could try google next time for yourself ? why Peter ? If he done this I will never found this interested link... thanks, Vasile -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

On 18-Feb-02 Ted Mawson wrote: > Peter, > > I've done extensive prior searches on Google. Google is my standard search > engine, it's in my favorites and is number 1 on my links bar; I'm not > someone who asks on this list before doing my own research if that was your > concern? So next time say that you have done a WEB search, then we will know where you are at already.... Your initial post spoke only of 74F161 which made it appear that you had looked no further than the TTL data book on your shelf ! > The Frequency counter you pointed to uses a prescaler which works OK but > means you lose the lowest 8 bits of binary resolution = 2560 kHz steps in > counting on /256 at a gate time of 0.1 secs. I think you are out by a factor of 1000 ! In a 0.1s count period the bit 0 of the counter equates to 10Hz, so bit 7 equates to 2560 Hertz not KILO Hertz. Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Summary of info I gleaned from this thread... PIC16F84 chips are good up to a max clock speed of 50-60 MHz (counting on the RA4 schmitt trigger input) 74HCxx chips are good up to a max clock speed of 36 MHz 74Fxx chips are good up to a maximum of 100-125 MHz ECL (emitter coupled logic) can get up to 2 GHz As Peter onion pointed out, I made a simmple error in that a 0.1s count period the bit 0 of the counter equates to 10Hz, so bit 7 equates to 2560 Hertz not KILO Hertz. Thanks to all. Ted Mawson KILLspamPICmanKILLspamportfoliopm.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body