| Electronics > Projects, Designs, and Technical Stuff |
| Using ESP32 and Neo-7N for precise frequency measurement |
| << < (7/11) > >> |
| ogden:
--- Quote from: tggzzz on September 14, 2018, 03:45:41 pm ---Yes you have missed something: XMOS processors and their software environment. --- End quote --- Nah. FPGA or ASIC is right tool :D (kidding) As I said - 1$ STM32 is enough for freq counter having core freq (72 MHz) granularity and no dependence on interrupt timing. Capture interrupt I mentioned before is just obvious and convenient way to avoid brute polling, interrupt timing/jitter is irrelevant. Disclaimer: I do not talk to OP here. |
| tggzzz:
--- Quote from: ogden on September 14, 2018, 06:01:17 pm --- --- Quote from: tggzzz on September 14, 2018, 03:45:41 pm ---Yes you have missed something: XMOS processors and their software environment. --- End quote --- Nah. FPGA or ASIC is right tool :D (kidding) As I said - 1$ STM32 is enough for freq counter having core freq (72 MHz) granularity and no dependence on interrupt timing. Capture interrupt I mentioned before is just obvious and convenient way to avoid brute polling, interrupt timing/jitter is irrelevant. Disclaimer: I do not talk to OP here. --- End quote --- FPGA will, of course, work. The XMOS processors are nibbling into FPGA territory. They contain 4 to 32 cores running at 100MHz. I haven't evaluated the stm32, so can't comment on that. |
| ogden:
--- Quote from: tggzzz on September 14, 2018, 07:27:20 pm ---I haven't evaluated the stm32, so can't comment on that. --- End quote --- If you are into timing/frequency measurement or control - you shall (evaluate). - Because only peripheral on stm32 that can be considered as good is timer. [rant on] If you are into DSP - stay away from stm32 because you can't clock it's ADC/DAC directly from crystal oscillator. [rant off] |
| tggzzz:
--- Quote from: ogden on September 14, 2018, 08:14:37 pm --- --- Quote from: tggzzz on September 14, 2018, 07:27:20 pm ---I haven't evaluated the stm32, so can't comment on that. --- End quote --- If you are into timing/frequency measurement or control - you shall (evaluate). - Because only peripheral on stm32 that can be considered as good is timer. [rant on] If you are into DSP - stay away from stm32 because you can't clock it's ADC/DAC directly from crystal oscillator. [rant off] --- End quote --- How fast a data stream can you capture? While also doing USB connection to a host PC? Whats the time resolution with which you can know when inputs occurred? Ditto specify when an output will occur? How many of those can you do simultaneously? How accurately can the IDE toolchain specify the minimum/maximum time a code path will take - without measuring and hoping you capture those conditions? I very much doubt it gets anywhere vaguely close to the xCORE processors! As as example, the xCORE tools easily predict without executing that (on a first generation XS1 device) a "float" multiply takes 1.032us max (0.408us min), and a "double" multiply takes 2.632us max (0.560 min). Don't forget that's per core, and there can be many cores executing simultaneously! |
| mark03:
--- Quote from: ogden on September 14, 2018, 08:14:37 pm ---If you are into timing/frequency measurement or control - you shall (evaluate). - Because only peripheral on stm32 that can be considered as good is timer. [rant on] If you are into DSP - stay away from stm32 because you can't clock it's ADC/DAC directly from crystal oscillator. [rant off] --- End quote --- That's funny, STM32L4 is my favorite for DSP projects. I make good use of the built-in hardware CIC filter. I do have a few quibbles on its implementation, but I don't know of any other CM4/7 MCU with a similar peripheral. What's the motivation for direct clocking from XO? Is jitter that much of an issue at these sample rates? In a precision design I'd be using an external ADC anyway. |
| Navigation |
| Message Index |
| Next page |
| Previous page |