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All the examples I've seen for ICSP use a MAX232, but the PICAXE 18X,
which is a PIC16F88, has a simple two-resistor serial interface. Any reasons why I can't use the resistor interface for PIC ICSP? Mike |
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16F88 bootloader
Started by ●August 8, 2004
Reply by ●August 8, 20042004-08-08
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> All the examples I've seen for ICSP use a MAX232, but the PICAXE
18X, > which is a PIC16F88, has a simple two-resistor serial interface. Are you talking about ICSP or self-programming (bootloader)? Do you care about reliability and reproduceability, or are you after the lowest possible cost-per-unit? Wouter van Ooijen -- ------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products |
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Reply by ●August 8, 20042004-08-08
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And don't forget that the MAX232 inverts, the resistors obviously
don't,
so you would have to take care of that somewhere. There are some hardware
hacks with transistors that would do the inversion, but might it not just
be easier to do it right. Bob U. At 08:59 AM 8/8/2004, you wrote: > All the examples I've seen for ICSP use a MAX232, but the PICAXE 18X, |
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Reply by ●August 8, 20042004-08-08
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--- In , Bob Underwood <aa6bt@r...> wrote: > And don't forget that the MAX232 inverts, the resistors obviously don't, so > you would have to take care of that somewhere. There are some hardware > hacks with transistors that would do the inversion, but might it not just > be easier to do it right. > > Bob U. There are bunches of RS232 chips other than the MAX232. is there any reason why that particular chip is required ? Often I see Maxim chips in designs because the hobby market uses free samples for the designs. Is the MAX232 required for the design ? What are the alternatives ? Dave |
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Reply by ●August 8, 20042004-08-08
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> There are bunches of RS232 chips other than the MAX232. is there any
> reason why that particular chip is required ? there is one good reason that chip is used very often (ok, three reasons): - it has been along a long time - it is available from just about any supplier - it is cheap Wouter van Ooijen -- ------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products |
Reply by ●August 8, 20042004-08-08
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I guess I was talking about both. I don't see why the ICSP interface
can't be the same as that for self-programming. Since no high voltage is used they're both just sending logic signals. Cost isn't really an issue since this is a single item project for myself. I just want simplicity and low power consumption - the MAX232 would consume power even when it's not used. Mike --- In , "Wouter van Ooijen" <wouter@v...> wrote: > > All the examples I've seen for ICSP use a MAX232, but the PICAXE 18X, > > which is a PIC16F88, has a simple two-resistor serial interface. > > Are you talking about ICSP or self-programming (bootloader)? > > Do you care about reliability and reproduceability, or are you after the > lowest possible cost-per-unit? > > Wouter van Ooijen > > -- ------- > Van Ooijen Technische Informatica: www.voti.nl > consultancy, development, PICmicro products |
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Reply by ●August 8, 20042004-08-08
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> I guess I was talking about both. I don't see why the ICSP
interface > can't be the same as that for self-programming. Since no high > voltage is used they're both just sending logic signals. Creating logic sequences with a serial port is not impossible but not easy (or fast) either, so doing ISCP directly is not popular for serious designs. It is used however for low-cost designs (check the ic-prog website for designs). The signals from a serial port are not logic-level, so you will need some kind of level converter. A simple resistor will often work. Whether that is enough for you is up to you to decide. > I just want simplicity and low power consumption - the > MAX232 would consume power even when it's not used. You don't mention reliability, so I guess the resitor approach is good enough for you :) Wouter van Ooijen -- ------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products |
Reply by ●August 8, 20042004-08-08
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it depends on what you mean by max232 vs other rs232 chips. There are a number of clones (er, second source versions) of the max232 that are cheaper and work pretty much the same. You'll need to distinguish between max232a and max232 clones, also. The non-A parts use larger caps (1 uf vs 0.1 uf). There are other rs232 drivers that should work just fine but I think the max232 design has plenty of examples and is easy to add to a project in a cook-book way so people just design it in. It doesn't hurt that you can get max232 clones for under a $1 if you look around. I bought a bunch off of ebay so that's what I use. --- In , "Dave Mucha" <dave_mucha@y...> wrote: > --- In , Bob Underwood <aa6bt@r...> wrote: > > And don't forget that the MAX232 inverts, the resistors obviously > don't, so > > you would have to take care of that somewhere. There are some > hardware > > hacks with transistors that would do the inversion, but might it > not just > > be easier to do it right. > > > > Bob U. > There are bunches of RS232 chips other than the MAX232. is there any > reason why that particular chip is required ? > > Often I see Maxim chips in designs because the hobby market uses free > samples for the designs. > > Is the MAX232 required for the design ? > What are the alternatives ? > > Dave |
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Reply by ●August 8, 20042004-08-08
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maybe this is a dumb question but 45 minutes of googling and searching various archives leads me to it: Is there a bootloader that runs on the 16F88?? I didn't see one. I like the chip and a bootloader would be a huge benefit. Maybe not quite enough for me to modify some other bootloader, though...\ Phil |
Reply by ●August 9, 20042004-08-09
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> I guess I was talking about both. I don't see why the ICSP
interface > can't be the same as that for self-programming. Since no high > voltage is used they're both just sending logic signals. If ICSP interface is the same as that for bootloader, then why using bootloader? > Cost isn't really an issue since this is a single item project for > myself. I just want simplicity and low power consumption - the > MAX232 would consume power even when it's not used. Use low power RS232 transceiver with shutdown and with receiver enabled while in shutdown. Regards, Igor |
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