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Which uController to learn?

Discussion in 'Electronic Components' started by John E., Mar 15, 2007.

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  1. John Barrett

    John Barrett Guest

    Its cheaper for me to buy a stick of chips with the quantity discount than
    it is to buy the minimal chip that will do the job each time I come up with
    a new project :) Plus I dont have to wait for the new chips to show up --
    always have a few on hand :) I've probably got 4 or 5 flavors of AVR hangin
    around... from 18 pin to 40 pin with various flash/ram/eeprom combos -- I
    just use whatever I got that will do the job at all :) havent run into a
    project yet where the processor was out of the idle loop more than 50% of
    the time :) hehehe I guess I could meet your criteria by cranking the clock
    speed down a bunch !! but for me -- the processor has only 2 speeds -- the
    fastest it will do without a crystal -- and the fastest it will do with one
    :) I dont see the point of putting a slower crystal in then having to bust
    nuts to make the code work.

    hehehehe ---- If I only used my Dual 2.8g hyperthreaded Xeon with 4 gigs ram
    to read newsgroups -- welllll :) but between editing DVD masters,
    programming AVRs and C#, designing databases, apps and websites, editing
    graphics, controlling my CNC mill, running 8-10 hour spice simulations on
    10kw power supplies, etc -- I tend to keep this sucker pretty busy most of
    the time :)

    I dont have a (working) laptop at the moment -- but the pub sounds like a
    good idea !!
  2. Tim Wescott

    Tim Wescott Guest

    68HC11, but it's old. I'll bet the 'HC12 and 'HC16 (do they still make
    those?) are good.

    AVR, if you don't mind wimpy pins.

    The TI MSP430 -- the small ones at least have oodles of pin drive, they
    appear to have a rational architecture, they're fast, and you can get a
    complete development system from TI for $20.

    ARM, if you don't mind wading through all the different versions that
    are available to find what you want (check those pin drive capacities!).
    The instruction set is rational, but only in a screwy, RISC sort of
    way. The capabilities are HUGE, and so is the set of mistakes you can
    make -- I wouldn't recommend it for a beginner.

    PowerPC -- Freescale has embedded versions. Same snarky comment about
    the instruction set as ARM, but still way better than a PIC.

    Those are the ones that I'm familiar with.

    Oh -- _not_ the Intersil/RCA 1802, unless you want to be an ace assembly
    language programmer. It was the very first processor I ever worked
    with, in 8th grade. I call it a NHISC -- Never Had an Instruction Set.
    I don't know if it's still around, but for quite a while it was the
    king of little space apps, because it had a huge geometry that could
    absorb cosmic rays without even noticing that they were there.


    Tim Wescott
    Wescott Design Services

    Posting from Google? See

    "Applied Control Theory for Embedded Systems" came out in April.
    See details at
  3. Riscy

    Riscy Guest

    I recommend Microchip PIC, starting 18F series because it has build in
    multiplier. £100 for complier package and £100 for ICD2 programmer/
    debugger. MPLAB is free.

    8052 and other processor is a consideration, but I started with PIC
    becuase it supported with training package, available offshelve,
    extensive range and easy to use. I developed successful project based
    on PIC. I'm now working on 2191 Analog Device DSP processor.

    Damn google no longer accept my email and change into more complex
    emil, so I say goodbye to this discussion group.
  4. You would not believe the followng this thing still has.
    It has become a cult thing with kids building them all over. I built mine
    in 1978 IIRC.
  5. mpm

    mpm Guest

    Somebody said...
    This gets back to the "intended-application" discussion.
    While it's nice to have a "family" of chips you've spent the better
    part of your adult engineering life understanding, there are times
    when you simply must stretch the envelope.

    Like my current project for instance.
    It has to "rob" power from something that was never intended to
    deliver it.
    I need to powerdown more than roughly 90% of the time, drawing no more
    than a few uA.
    And not much more than 100uA for the other 10% of the time.
    Oh, and for that, the clock speed is barely 20kHz (+/- 10%).

    I think "MIPS" is a pipe dream for this one.
  6. krw

    krw Guest

  7. linnix

    linnix Guest

    Or last at long as possible on battery.
    I need uA in stand-by. Full speed (Usb or Serial) while connected.
    So, I need it very slow and very fast. For Serial, Avr tops at 19,000
    and Arm tops at 920,000 baud. Avr has Usb option but Arm hasn't.
  8. The phone line?
    That would be a high duty cycle for a phone line, unless you need to wake up
    frequently to see if touch tones are being sent.
    Yep, sounds right in line for a PIC though. 12F683 (my new favorite) ~500
    uA at 5V running full tilt on the internal oscillator (8MHz, 1% accuracy),
    11uA at 32KHz (2V). Change speeds on the fly. Who needs to sleep? ;-)
    You can sleep if you want, bit it'll cost you 50nA.
  9. jasen

    jasen Guest

    no it's not, it has too few registers to qualify.
    It always seemed kind of awkward and slow slow to me.

  10. jasen

    jasen Guest

    Many of them are doing 20 MIPS now, that wasn't available two years ago,
    built-in full speed USB is new too,

    It's an 8-bit microcontroller it doesn't need that extra stuff ...

  11. jasen

    jasen Guest

    that'd be because you're running such a slow clock.
    at only 1.8432 Mhz you can 115200 baud. basically 1/16 your clock.
    yeah, but at what clock speed.

  12. linnix

    linnix Guest

    No, it won't. At 2 MHz, AVR have lock-ups for 38,400 baud.
    My AVR clock toggles between 2 MHz and 32KHz.
    20 MHz.
  13. By whose definition? It stands for Reduced Instruction Set. 35
    instructions is pretty reduced IMO.
    Compared to what? 10MIPs on a few mA is pretty good in my book.
  14. jasen

    jasen Guest

    "lock ups?"

    The attiny2313 "data sheet" suggests it should be capable of 250Kbps
    (asynchronous serial) at 2mhz

    With a 2MHz clock 38400 baud isn't really an option on that hardware,
    35714.3 or 41666.7 are the closest choices.

    If you reduce the clock to 1.8432 Mhz (should be a standard size)
    38400.0 is available (as are the other standard speeds upto 230400)
    Not with the uart running I hope!
    How does it manage that? 920K doesn't divide 20M, is there an internal PLL
    or something?

    Anyway it seems kind of slow :^)

    Some people bit-bang USB at 1.5Mb/s on 12Mz AVRs. (as a non-interruptable
    foreground task) again the trick is to pick a clock rate that's a
    sufficiently high multiple of the data rate.

  15. 20 MIPS, on a MEGA. Those aren't backwards compatible with the tradition
    AVRs are they?
    Speak for yourself. Since when is A/D resolution not important for an 8
  16. krw

    krw Guest

    Actually, it stands for "Reduced Instruction Set Complexity". It has
    nothing to do with the number of instructions (PowerPC is certainly
    RISC, yet has hundreds of instructions in even more varieties),
    rather the complexity of the instructions. For example, no
    arithmetic operations on memory are allowed, only load/stores.
  17. John Barrett

    John Barrett Guest

    RISC essentially means that EVERY instruction takes ONE clock cycle, so your
    clock speed is your IPS -- CISC chips like the 80x86 take anywhere from
    4-??? instructions per clock, they internally decode instructions through a
    micro-code rom in the CPU that sequences the internal processing elements of
    the chip through the steps neccessary to perform the instruction -- for
    instance -- a single instruction may read memory, add it to a register, and
    write the result back to memory -- all in one instruction, but across
    multiple clock cycles.

    Therefore there are things a CISC chip can do in one ASM instruction that a
    RISC chip cannot do, simply because there is no way to perform the operation
    in a single clock cycle... for instance -- the 80x86 has a single
    instruction memory copy capability for moving data around -- makes things a
    little easier on the compiler developers.
  18. John Barrett

    John Barrett Guest

    AVR32 based 32-bit MCU/DSP
    Vectored multiplier co-processor, 32 KB on-chip SRAM, 16 KB instruction and
    16 KB data caches, MMU, DMA controller. Peripherals include a 16-bit stereo
    audio DAC, 2048x2048 pixel TFT/STN LCD controllers, 480 Mbps USB 2.0 with on
    chip transceivers (PHY) and, two 10/100 Ethernet MACs. Serial interfaces
    include RS232, USART, I2S, AC97, TWI/I2C, SPI, PS/2 and several synchronous
    serial modules (SSC) supporting most serial communication protocols.

    sounds like a bit more than an 8-bitter to me !!
  19. krw

    krw Guest

    Nope. RISC == "Reduced Instruction Set Complexity". It has nothing
    to do with IPS. RISC is a philosophy. IPS is a design trade-off.
    The PowerPC *is* a RISC architecture. Some PowerPC implementations
    (e.g.. PPC750) tend to be one-cycle through the execution unit (plus
    decode, etc) where the Power5 is the same architecture and may be 5
    to 15 cycles through the execution unit.

    The x86 processors have memory reference arithmetec instructions
    It's RISC, not because it can do more than one thing per instruction,
    but because it can operate on memory with one instruction. BTW, RISC
    compilers are *far* easier to write; one of the reasons RISC was
    invented. RISC processors tend to be register rich, since they
    cannot operate on memory.
  20. DJ Delorie

    DJ Delorie Guest

    This is an invalid generalization. Compiler complexity depends on
    many factors, and the raw size of the instruction set isn't even near
    the top of the list. Specialization is a more key factor, and RISC
    chips tend to have more specialized instructions. A CISC chip, for
    example, can usually add anything to anything, whereas RISC chips can
    only add registers, and sometimes add constants to a register.

    The top of the list is usually "customer's requests for unique
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