[HN Gopher] A Guide to Pic Microcontroller Paging
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A Guide to Pic Microcontroller Paging
Author : Jetroid
Score : 17 points
Date : 2020-06-13 04:54 UTC (18 hours ago)
(HTM) web link (jetholt.com)
(TXT) w3m dump (jetholt.com)
| lmilcin wrote:
| Can somebody explain why anybody would want to put up with PIC in
| 2020 when ARMs are so cheap and energy efficient and development
| tools got to a point where you get working toolchain with no time
| or money expense (for example with stm32cubeide and st-link)?
| analog31 wrote:
| I was about to say that only PIC chips come in 8- and 6-pin
| packages, but I see that I'm wrong about that. Microchip's
| patent must have run out fairly recently.
|
| I gave up on the PIC platform quite some time ago.
| lmilcin wrote:
| Some STM32s are available in WLCSP packages which are
| 2.5x2.5mm and have 36 pins.
|
| https://electronics.stackexchange.com/questions/144005/wlcsp.
| ..
| zokier wrote:
| ATtinys have been available in 8 pin packages for about 2
| decades, and in 6 pin packages for 1 decade. What patents are
| you referring to?
| joshvm wrote:
| PIC extreme low power (xlp) is ridiculously low - at least an
| order of magnitude lower sleep current (9nA) than ARM
| equivalents. They also have very low uA/Mhz, but some ARM chips
| are approaching or exceeding that (eg SAM L).
|
| There's also something to be said for simplicity and ease of
| hardware development, as opposed to a race to the bottom on
| price. Do you necessarily need all that ARM grunt? 8 bit micros
| tend to need very little support circuitry and can have very
| low pin counts - eg the PIC10F322 is 6 pin, 20nA sleep current
| and comes in a DFN package.
|
| There are also applications where having a DIP package chip is
| useful (easy replacement, for example).
| alex7o wrote:
| There is no good commercial reason to go with a pic, there are
| cheaper 8bit MCU s like 0.01$ cheap or even less, or as you
| said arm ones that are much faster, with free tooling and good
| JTAG/swd debugging. However there are millions of PICs that are
| still used so it is useful to know these things.
| m-ee wrote:
| I haven't looked into the ultra cheap stuff in a while, are
| you talking about other 8 but mcus from major manufacturers
| or the ultra cheap no name alibaba stuff? PICs historically
| have good data sheets which is worth a non trivial amount of
| money
| joefourier wrote:
| That's the mentality that leads to toasters running Linux. For
| many applications there's absolutely no need for ARM MCUs and
| all their added complexity.
|
| Plus for the hobbyist at home, PIC still comes in DIP formats
| which is handy for breadboarding or soldering without the added
| difficulty of SMT.
| zozbot234 wrote:
| RISC-V will probably be more of a competitor to PIC once
| suppliers really get going. There's even a standard RV32E spec
| that's limited to 16 registers, which should make for tiny area
| footprint even in old process nodes.
| indigo945 wrote:
| Technically, the second block of code is not 100% equivalent.
| Why? Well, it uses more instructions (so more memory and
| also takes longer to execute) but it also sets ALL bits of
| the Program Counter, not just the ones that a goto or call
| can. We could use the second block of code to goto
| to a correct page, but it would be annoying to use in
| practice because it would mangle the W register.
|
| Does the code even work at all? I don't know anything about PIC
| microcontrollers, but I would have expected that writing to
| PCLACH would cause a jump immediately, meaning that the write to
| the low bits in PCL would never even happen.
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(page generated 2020-06-13 23:00 UTC)