Post by thread:[AVR]: Wondering about the avr...

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'[AVR]: Wondering about the avr...'
2002\08\24@065942 by Jan Malina

Been looking at pics mostly for microcontroler work, but i stumbled accros the atmel ones, and i wonder, what are the strong/weak points of them compared to the PIC microcontrolers? as they do seem cheaper... Jan -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

2002\08\24@094651 by Byron A Jeff

On Sat, Aug 24, 2002 at 10:38:31AM +0200, Jan Malina wrote: > Been looking at pics mostly for microcontroler work, but i stumbled accros > the atmel ones, and i wonder, what are the strong/weak points of them > compared to the PIC microcontrolers? as they do seem cheaper... I'll take a crack: AVR Pros -------- * Cost effective * No paging/banking issues * Flash based w/ simple programming hardware * Industry standard Intel 8051 ISA * Reasonable program memory, I/O, and RAm resources * Truly free unlimited use/resources C compiler AVR Cons -------- * Perception of lack of availabilty. It was a reality in the past so it had a kernel of truth. Probably scared off a lot of developers permanently. PIC Pros -------- * Cost effective. Mchip has an amazing way of adding more but reducing cost. * Flash/EPROM based w/ simple programming hardware * Industry standard PIC ISA * Reasonable program memory, I/O, and RAM resouces * Fast execution of one instruction per cycle * True RISC ISA w/ only 35 instructions for the 16F midrange family * Once in production very high availability and longevity * Industry standard free development environment: MPLAB * Access to one of the greatest PIC resources, the PICLIST ;-) PIC Cons -------- * The funky architecture: banking * The funky architecture: paging * The funky architecture: RMW instructions on I/O ports * The funky architecture You really can't lose. It just that you'll have a different set of resources to use if you pick one over the other. Personally I picked the PIC and stuck to it simply because there'd be a heavy cost to switching and there's nothing in the cost profile that's significant enough to warrant a change. Good Luck. BAJ -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

2002\08\24@114056 by Geo

On 24 Aug 2002, at 9:00, Byron A Jeff wrote: > AVR Pros > -------- You forgot * Fast execution of one instruction per cycle I'll add--- Hardware UART on 20 pin AT90S2313 Easy reading from 'program' memory (LPM instruction) 16 general purpose registers including three 16 bit pointers with all the auto inc/dec etc > AVR Cons > -------- > * Perception of lack of availabilty. It was a reality in the past so it had > a kernel of truth. Probably scared off a lot of developers permanently. Agreed - I had to design a PCB dual 20pin/40 pin to take 2313/4414 when the 2313 disappeared for a few months. No ADD immediate - you have to use SUBI with a negative number - not very intuitive. George Smith -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

2002\08\24@114242 by mike

On Sat, 24 Aug 2002 09:00:21 -0400, you wrote: >On Sat, Aug 24, 2002 at 10:38:31AM +0200, Jan Malina wrote: >> Been looking at pics mostly for microcontroler work, but i stumbled accros >> the atmel ones, and i wonder, what are the strong/weak points of them >> compared to the PIC microcontrolers? as they do seem cheaper... > >I'll take a crack: > >AVR Pros >-------- >* Cost effective >* No paging/banking issues >* Flash based w/ simple programming hardware >* Industry standard Intel 8051 ISA >* Reasonable program memory, I/O, and RAm resources >* Truly free unlimited use/resources C compiler Uart TX and RX can be enabled seperately UART can do high baudrates at low clocks >AVR Cons >-------- >* Perception of lack of availabilty. It was a reality in the past so it had > a kernel of truth. Probably scared off a lot of developers permanently. High power consumption at 5V Non-consistent interrupt response time (can be a problem with timer ints) EEPROM can get corrupted in brownout Lower output drive than PICs Inconsistent skip/branck instructions (some times you use skips, sometimes you use branches, and they can only branch +/-128 bytes, leading to spaghetti code...) No immediate XOR Will not wake from sleep on an edge (needs input held til CPU wakes up) -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

2002\08\24@114402 by mark

On 24 Aug 2002 at 9:00, Byron A Jeff wrote: > PIC Pros > -------- > * Cost effective. Mchip has an amazing way of adding more but reducing cost. > * Flash/EPROM based w/ simple programming hardware > * Industry standard PIC ISA > * Reasonable program memory, I/O, and RAM resouces > * Fast execution of one instruction per cycle This one would be in the ATMEL Pros. -------------------- Marcelo Puhl http://py3ss.cjb.net -------------------- -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

2002\08\24@153608 by Wouter van Ooijen

> AVR Pros > * Industry standard Intel 8051 ISA ??? AVR is an ISA of its own, an way better IMHO than either 8051 or PIC (-12 or -14) > PIC Pros > * Industry standard PIC ISA ??? Who's standard? If that is a standard (at least then it are three standards: pic-12, pic-14, pic-16, maybe I missed a few because they don't flash) then Jal is gona be an industry standard too! > You really can't lose. Can't disagree with that. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

2002\08\24@180010 by Dave Tweed

Byron A Jeff <@spam@byronKILLspamCC.GATECH.EDU> wrote: > I'll take a crack: > > AVR Pros > -------- > * Industry standard Intel 8051 ISA Don't confuse the Atmel 89xxxx parts (8051 ISA) with their 90Sxxxx and "mega" series; only the latter two are AVR ISA. -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

2002\08\24@180017 by Dave Tweed

Mike Harrison <RemoveMEmikeTakeThisOuTWHITEWING.CO.UK> wrote: > >AVR Cons > >-------- > High power consumption at 5V > Non-consistent interrupt response time (can be a problem with timer ints) What causes that? Several years ago, I tried to prototype an application on a 90S1200 in which I needed to take precisely-timed samples of the output of the analog comparator. I could never get this to work right and eventually gave up on trying to use the AVR. Which is too bad, because in many other respects it was the ideal chip for the job. -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu

2002\08\24@180232 by fred jones

I didn't consider atmel when I was looking because at the time they were tough to get. Aparently they aren't anymore. My only complaint about PICs is the bank/page switching. I can't tell you how many times that has bitten me. It may be true that PICs have fast single cycle instructions, but my 20mhz is divided by 4 so am I really seeing single cycle execution? I feel like I'm giving up at least 4 for every instruction. Then add up all the extra page and bank switching commands that are extra time consuming instructions and I'm not sure I've gained anything. If my 16F877 didn't require the switching, I'd have no complaints. Good luck, Fred {Quote hidden}>From: Byron A Jeff <TakeThisOuTbyronEraseMEspam_OUTCC.GATECH.EDU> >Reply-To: pic microcontroller discussion list <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> >To: PICLISTEraseME.....MITVMA.MIT.EDU >Subject: Re: [AVR]: Wondering about the avr... >Date: Sat, 24 Aug 2002 09:00:21 -0400 > >On Sat, Aug 24, 2002 at 10:38:31AM +0200, Jan Malina wrote: > > Been looking at pics mostly for microcontroler work, but i stumbled >accros > > the atmel ones, and i wonder, what are the strong/weak points of them > > compared to the PIC microcontrolers? as they do seem cheaper... > >I'll take a crack: > >AVR Pros >-------- >* Cost effective >* No paging/banking issues >* Flash based w/ simple programming hardware >* Industry standard Intel 8051 ISA >* Reasonable program memory, I/O, and RAm resources >* Truly free unlimited use/resources C compiler > >AVR Cons >-------- >* Perception of lack of availabilty. It was a reality in the past so it had > a kernel of truth. Probably scared off a lot of developers permanently. > >PIC Pros >-------- >* Cost effective. Mchip has an amazing way of adding more but reducing >cost. >* Flash/EPROM based w/ simple programming hardware >* Industry standard PIC ISA >* Reasonable program memory, I/O, and RAM resouces >* Fast execution of one instruction per cycle >* True RISC ISA w/ only 35 instructions for the 16F midrange family >* Once in production very high availability and longevity >* Industry standard free development environment: MPLAB >* Access to one of the greatest PIC resources, the PICLIST ;-) > >PIC Cons >-------- >* The funky architecture: banking >* The funky architecture: paging >* The funky architecture: RMW instructions on I/O ports >* The funky architecture > >You really can't lose. It just that you'll have a different set of >resources to use if you pick one over the other. Personally I picked the >PIC and stuck to it simply because there'd be a heavy cost to switching and >there's nothing in the cost profile that's significant enough to warrant a >change. > >Good Luck. > >BAJ > >-- >http://www.piclist.com hint: To leave the PICList >EraseMEpiclist-unsubscribe-requestmitvma.mit.edu _________________________________________________________________ Join the world s largest e-mail service with MSN Hotmail. http://www.hotmail.com -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestEraseMEEraseMEmitvma.mit.edu

2002\08\24@194949 by Jinx

> me. It may be true that PICs have fast single cycle instructions, > but my 20mhz is divided by 4 so am I really seeing single cycle > execution? I feel like I'm giving up at least 4 for every instruction An 8MHz AVR is faster than a 20MHz PIC, as the PIC has a /4 clock system, so is effectively running at 5MHz. I'd be interested to know if there are any bench mark routine comparisons around of AVR vs PIC for task completion in "real world" applications -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestspam_OUTKILLspammitvma.mit.edu

2002\08\24@195004 by Byron A Jeff

On Sat, Aug 24, 2002 at 02:25:22PM -0700, Dave Tweed wrote: > Byron A Jeff <RemoveMEbyronTakeThisOuTspamCC.GATECH.EDU> wrote: > > I'll take a crack: > > > > AVR Pros > > -------- > > * Industry standard Intel 8051 ISA > > Don't confuse the Atmel 89xxxx parts (8051 ISA) with their 90Sxxxx and > "mega" series; only the latter two are AVR ISA. Thanks for the clarification Dave. I thought I was going crazy. But as you all well know I'm a PicDude (like Neil ;-) So I really wasn't aware that the 90s and Mega part had changed ISAs. So what's the target for the free AVR C Compiler? BAJ -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspamspamBeGonemitvma.mit.edu

2002\08\24@195058 by mike

On Sat, 24 Aug 2002 14:25:35 -0700, you wrote: >Mike Harrison <RemoveMEmikeKILLspamWHITEWING.CO.UK> wrote: >> >AVR Cons >> >-------- >> High power consumption at 5V >> Non-consistent interrupt response time (can be a problem with timer ints) > >What causes that? Variable-length instructions. For example, if you set up a timer interrupt on a PIC, it occurs with rock-solid regularity. With an AVR there will be jitter - I think up to 3 cycles, as the interrupt latency is longer if the foreground task is executing a longer instruction. As AVR instructions can take 1, 2, 3 or 4 cycles. This will only be an issue in certain types of application, where regular timing off interrupts (e.g. generating external waveforms) is important. Although some PIC instructions take 2 cycles, the pipelining behaviour ensure that interrupt latency from internal-clock-generated interrupts is consistent. .of course the AVR's multiple interrupt vectors and better context-saving is MUCH MUCH nicer than the PIC for handling multiple interrupt sources. >Several years ago, I tried to prototype an application on a 90S1200 in >which I needed to take precisely-timed samples of the output of the analog >comparator. I could never get this to work right and eventually gave up on >trying to use the AVR. Which is too bad, because in many other respects it >was the ideal chip for the job. > >-- Dave Tweed -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestSTOPspamspam_OUTmitvma.mit.edu

2002\08\24@195105 by mike

Unless you're really hammering things, it is often the case that the 1-cycle thing isn't much of an advantage, for example if you can do it on a 4MHz pic, a 1MHz AVR would be _roughly_ equivalent, but you try finding a cheap 3-terminal 1MHz ceramic resonator...! You end up using a higher clock than necessary, at the expense of power. On Sat, 24 Aug 2002 16:50:21 -0500, you wrote: {Quote hidden}>I didn't consider atmel when I was looking because at the time they were >tough to get. Aparently they aren't anymore. My only complaint about PICs >is the bank/page switching. I can't tell you how many times that has bitten >me. It may be true that PICs have fast single cycle instructions, but my >20mhz is divided by 4 so am I really seeing single cycle execution? I feel >like I'm giving up at least 4 for every instruction. Then add up all the >extra page and bank switching commands that are extra time consuming >instructions and I'm not sure I've gained anything. If my 16F877 didn't >require the switching, I'd have no complaints. >Good luck, >Fred > > >>From: Byron A Jeff <spamBeGonebyronSTOPspamEraseMECC.GATECH.EDU> >>Reply-To: pic microcontroller discussion list <KILLspamPICLISTspamBeGoneMITVMA.MIT.EDU> >>To: EraseMEPICLISTEraseMEMITVMA.MIT.EDU >>Subject: Re: [AVR]: Wondering about the avr... >>Date: Sat, 24 Aug 2002 09:00:21 -0400 >> >>On Sat, Aug 24, 2002 at 10:38:31AM +0200, Jan Malina wrote: >> > Been looking at pics mostly for microcontroler work, but i stumbled >>accros >> > the atmel ones, and i wonder, what are the strong/weak points of them >> > compared to the PIC microcontrolers? as they do seem cheaper... >> >>I'll take a crack: >> >>AVR Pros >>-------- >>* Cost effective >>* No paging/banking issues >>* Flash based w/ simple programming hardware >>* Industry standard Intel 8051 ISA >>* Reasonable program memory, I/O, and RAm resources >>* Truly free unlimited use/resources C compiler >> >>AVR Cons >>-------- >>* Perception of lack of availabilty. It was a reality in the past so it had >> a kernel of truth. Probably scared off a lot of developers permanently. >> >>PIC Pros >>-------- >>* Cost effective. Mchip has an amazing way of adding more but reducing >>cost. >>* Flash/EPROM based w/ simple programming hardware >>* Industry standard PIC ISA >>* Reasonable program memory, I/O, and RAM resouces >>* Fast execution of one instruction per cycle >>* True RISC ISA w/ only 35 instructions for the 16F midrange family >>* Once in production very high availability and longevity >>* Industry standard free development environment: MPLAB >>* Access to one of the greatest PIC resources, the PICLIST ;-) >> >>PIC Cons >>-------- >>* The funky architecture: banking >>* The funky architecture: paging >>* The funky architecture: RMW instructions on I/O ports >>* The funky architecture >> >>You really can't lose. It just that you'll have a different set of >>resources to use if you pick one over the other. Personally I picked the >>PIC and stuck to it simply because there'd be a heavy cost to switching and >>there's nothing in the cost profile that's significant enough to warrant a >>change. >> >>Good Luck. >> >>BAJ >> >>-- >>http://www.piclist.com hint: To leave the PICList >>@spam@piclist-unsubscribe-request@spam@spam_OUTmitvma.mit.edu > > > > >_________________________________________________________________ >Join the world s largest e-mail service with MSN Hotmail. >http://www.hotmail.com -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestKILLspammitvma.mit.edu

2002\08\24@224100 by Mike Singer

ATmega169: Low power LCD device Among the brand new features in this device is a LCD interface! (25x4). The Device is only available in a 64-pin TQFP, and have 53 general IO lines and in addition a input only pin is added to the RESET pin. (making it the AVR with most IO lines!) Another interesting feature is the possibility of generating interrupt on 17 external pins! This is 5 more than ATtiny26 which rank #2 on the external interrupts rating. The memories are 16kB Flash, 512B EE and 1kB SRAM, in other words a standard 16k memory configuration. Another very interesting feature is that this device runs @ 1.8V and contains an ADC. Because of the low voltage, the internal voltage reference on this device is 1.1V compared to 2.56V on all other AVRs. The ATmega169 is also very power efficient. From the datasheet: -Active Mode: 1 MHz, 1.8V: 300µA 32 kHz, 1.8V: 20µA (including Oscillator) 32 kHz, 1.8V: TBD (including Oscillator and LCD) -Power-down Mode: 0.5µA at 1.8V http://www.avrfreaks.net/Devices/devices.php?action=1&devid=71 ------------------------------- Mike. -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

2002\08\25@070055 by Wouter van Ooijen

> An 8MHz AVR is faster than a 20MHz PIC, as the PIC has a /4 > clock system, so is effectively running at 5MHz. I'd be interested > to know if there are any bench mark routine comparisons around > of AVR vs PIC for task completion in "real world" applications I would guess that the AVR would lead in arithmetic and RAM->RAM activities, while the PICs would lead in I/O intesive operations. So you should take great care defining a "real world" application, and even more care interpreting the results. BTW for true speed nothing beats an SX at 75 MHz (no /4) - OK, an SX at 100 MHz but those are no longer sold. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@073039 by Katinka Mills

> -----Original Message----- > From: pic microcontroller discussion list > [TakeThisOuTPICLIST.....TakeThisOuTMITVMA.MIT.EDU]On Behalf Of Wouter van Ooijen > Sent: Sunday, 25 August 2002 6:59 PM > To: TakeThisOuTPICLISTKILLspamspamMITVMA.MIT.EDU > Subject: Re: [AVR]: Wondering about the avr... > > > > An 8MHz AVR is faster than a 20MHz PIC, as the PIC has a /4 > > clock system, so is effectively running at 5MHz. I'd be interested > > to know if there are any bench mark routine comparisons around > > of AVR vs PIC for task completion in "real world" applications > > I would guess that the AVR would lead in arithmetic and RAM->RAM > activities, while the PICs would lead in I/O intesive operations. So you > should take great care defining a "real world" application, and even > more care interpreting the results. Why would you say that AVR is no a leader in I/O intensive operations ? I have no problems doing most things on an AVR, I actully use an AT90S8515 running at 8Mhz to merge and transmit the merged data stream of DMX 512, running at 250Kbps. Regards, Kat. ********************************************** K.A.Q. Electronics. Electronic and Software Engineering. Perth, Western Australia. Ph +61 (0) 419 923 731 ********************************************** --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.384 / Virus Database: 216 - Release Date: 21/08/2002 -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@074327 by Wouter van Ooijen

IIRC (has been a long time) it takes a few AVR instructions to set or celar a single output pin (also to decide on the value of a single pin?) Wouter > Why would you say that AVR is no a leader in I/O intensive > operations ? -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@081111 by Katinka Mills

> -----Original Message----- > From: pic microcontroller discussion list > [.....PICLISTRemoveMEMITVMA.MIT.EDU]On Behalf Of Wouter van Ooijen > Sent: Sunday, 25 August 2002 7:43 PM > To: RemoveMEPICLISTspamBeGoneMITVMA.MIT.EDU > Subject: Re: [AVR]: Wondering about the avr... > > > IIRC (has been a long time) it takes a few AVR instructions to set or > celar a single output pin (also to decide on the value of a single pin?) Ummmm to set or clear a port pin, you say SBI to set a bit, CBI to clear a bit. I can test a pin with a single instruction too SBIC is skip if bit in IO is cleared and SBIS is skip if bit in IO is wet. Regards, Kat. ********************************************** K.A.Q. Electronics. Electronic and Software Engineering. Perth, Western Australia. Ph +61 (0) 419 923 731 ********************************************** --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.384 / Virus Database: 216 - Release Date: 21/08/2002 -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@084240 by Roman Black

Jinx wrote: > An 8MHz AVR is faster than a 20MHz PIC, as the PIC has a /4 > clock system, so is effectively running at 5MHz. I'd be interested > to know if there are any bench mark routine comparisons around > of AVR vs PIC for task completion in "real world" applications Didn't Microchip claim "2:1 code compression and UP TO a 2:1 speed improvement (at 10MHz) over other 8-bit microcontrollers in their class"?? I assume they mean a 10MHz PIC is "up to" twice as fast as the average micro in the "class" as they couldn't claim to be twice as fast as the average 10MHz micro (which would mean 8 times as fast!?) :o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@093933 by Pic Dude

Whereas I've never needed to run a pic at max frequency (nothing I do has been that speed critical), I can see this non-div-by-4 clock as being useful for getting the max speed out of a processor while meeting the FCC 1.705Mhz exemption threshold. Cheers, -Neil. > {Original Message removed}

2002\08\25@093937 by Pic Dude

> But as you all well know I'm a PicDude (like Neil ;-) Woo-hoo! Honorable mention! -Neil. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@133238 by Morgan Olsson

Hej Wouter van Ooijen. Tack för ditt meddelande 12:43 2002-08-25 enligt nedan: >IIRC (has been a long time) it takes a few AVR instructions to set or >celar a single output pin (also to decide on the value of a single pin?) The other way around! One instr on AVR. On PIC often a mirror register is to be used for i/o because of the dreaded read-mod-write is reading from pins, possibly reading in a transient into otput registers if you midify an output. Thus at least three instr is needed on PIC making it much slower. Only safe way is to modufy in memory, then copy that whole byte to output. The AVR read-mod-write from output _Latch_ ignoring actual pin level. /Morgan -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@142403 by Peter L. Peres

On Sun, 25 Aug 2002, Pic Dude wrote: >Whereas I've never needed to run a pic at max frequency (nothing I >do has been that speed critical), I can see this non-div-by-4 clock >as being useful for getting the max speed out of a processor while >meeting the FCC 1.705Mhz exemption threshold. By the way what is the status of internal clock ? If one takes a 12C508A f.ex. and uses internal RC then what clock frequency does it run on for FCC purposes ? none ? In my experience a poorly decoupled switching stage using a fet makes much more noise than a PIC in such a configuration. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@152726 by Jim

"If one takes a 12C508A f.ex. and uses internal RC then what clock frequency does it run on for FCC purposes ?" Gee, I can see major spurs (spurious) being created at the 'clock' frequency (what ever f the proc core is clocked at), determined by whatever the RC combo works that out to be, and if you *fail* to think that just because a uP w/o a crystal *has* no oscillator then it will be the first visit by the FCC in one of their field enforcement bureau vans with a spectrum analyzer that points out the errors of your ways ... If in doubt, "range check it" ... **Seriously** - - the PIC with everything on-board has GOT to be the one of the cleanest uPs on the market. I have a Z80 design that spews garbage EVERYWHERE - but it's not marketed or sold so I can get away with it. It creates noticable 'spurs' (carriers) throughout the HF spectrum and even causes noticable herring bone patters on VHF-Low TV channels ... the Z80 design uses every peripheral IC in the Z80 family plus RAM and EPROM IC. The board design is only two-sided w/no Ground plane and the traces are run nearly everywhere! Ground and power are .1" parallel buses running under each IC, joining together to the main .1" bus. Bypass caps are present at each IC. It is also very noticable *which* routines are running in the code - there are several "phase-locked loops" in software that lock onto externally supplied data (Motorola trunking signals) and so the CPU is constantly servicing interrupts due to timers and edge transitions, perfroming timed scanning of keypad and updating data to LCD display *desides* doing error det and corr for a rate 1/2 convolutional data decoder and a block parity checker. RF Jim "Our ability to manufacture fraud has exceeded our ability to detect it." - Al Pacino as Viktor Taransky in the movie 'Simone' {Original Message removed}

2002\08\25@162310 by Peter L. Peres

On Sun, 25 Aug 2002, Jim wrote: > "If one takes a 12C508A f.ex. and uses internal > RC then what clock frequency does it run on for > FCC purposes ?" > >Gee, I can see major spurs (spurious) being created >at the 'clock' frequency (what ever f the proc core is >clocked at), determined by whatever the RC combo works >that out to be, and if you *fail* to think that just Of course one has proper decoupling. I was unable to measure noise at the suspected clock frequency with a scope. Maybe there is enough signal to look with a spectrum analyzer. I was looking at the Vcc node with capacitive coupling on the lowest scale my scope has (5mV/div) with 1:1 probe. Decoupling was 10uF tantalum + 0.1uF chip ceramic on very short leads. I tried to put a choke in series with the supply with the same result. Pretty good imho. The PIC was running a simple program that outputs 50kHz signals to drive a pair of mosfets. These were not connected when I did the measurement. Tiny 50kHz 'blips' were present corresponding to the flanks of the 50kHz signals but no trace of 4MHz or 1MHz could be seen. {Quote hidden}> >- the PIC with everything on-board has GOT to be the one >of the cleanest uPs on the market. I have a Z80 design >that spews garbage EVERYWHERE - but it's not marketed >or sold so I can get away with it. It creates noticable >'spurs' (carriers) throughout the HF spectrum and even >causes noticable herring bone patters on VHF-Low TV >channels ... the Z80 design uses every peripheral IC in >the Z80 family plus RAM and EPROM IC. The board design >is only two-sided w/no Ground plane and the traces >are run nearly everywhere! I once built one of those 16F84+LCD counters (I still have it and use it sometimes). It uses the resistor gate 'switch' scheme with two sections of a HC00 biased in the linear region as preamp. With this I can see hash on UHF TV when the box is near the TV cable. The hash occurs when the PIC clocks out the prescaler. It cannot be produced by the HC00 (whose input is shorted at the time of measurement with a 50 ohm plug). The circuit is in a plastic box and is breadboarded. The fast edges on the PIC output clocking the prescaler are sneaking out ... there is no trace of oscillator noise/hash/moire (the osc is built tight and has a wire loop as guard around its parts on the circuit side, the crystal can is grounded). Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2002\08\25@173951 by Pic Dude

I believe the FCC refers to the max frequency used anywhere in the circuit, so internal frequency would matter here. Cheers, -Neil. > {Original Message removed}

2002\08\26@101902 by mike

Does the exemption include harmonics... seems pretty meaningless if not.... I imagine a 1MHz PIC driving 74AC series logic with long tracks on the output would radiate way more than a 4MHz pic on its own with similarly long tracks.... On Sun, 25 Aug 2002 17:37:40 -0400, you wrote: >I believe the FCC refers to the max frequency used anywhere >in the circuit, so internal frequency would matter here. > >Cheers, >-Neil. > > > >> {Original Message removed}

2002\08\27@202844 by Max Foo

I'd stay clear of the atmel's avr. have you looked at Atmels stock price (about $2) compared to Microchip($20 something) just a matter of time til atmel declares chapter 11 now do you want to be hold a worthless avr chip with no tech support? let the flames begin ;) On Sat, 24 Aug 2002 10:38:31 +0200, you wrote: >Been looking at pics mostly for microcontroler work, but i stumbled accros >the atmel ones, and i wonder, what are the strong/weak points of them >compared to the PIC microcontrolers? as they do seem cheaper... > >Jan -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

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