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To conserve power (_CLKMODE = XTAL1 + PLL1X, _XINFREQ = 5_000_000) — Parallax Forums

To conserve power (_CLKMODE = XTAL1 + PLL1X, _XINFREQ = 5_000_000)

Hi,

I use a RN4020 bluetooth device and USR-K3 Ethernet device with a propeller.
I try to conserve power using a frequency lower that 80 Mhz.
The frequency that I would like to use is 5 MHz.
The communication between devices and propeller is 9600 and the communication with the terminal is 57600

I don't understand why at 5 Mhz the communication between propeller and USR-K3 Ethernet device works whereas it doesn't work with RN4020 bluetooth device.
The communication between propeller and RN4020 works only at 10 MHz and higher but not at 5 Mhz.
When I communicate at 5 Mhz, the responses of bluetooth device I display on terminal don't match (I get special characters)

If anyone has an hint, I would appreciate

Comments

  • SeairthSeairth Posts: 2,474
    edited 2017-06-13 17:36
    (deleted)
  • Some devices are more picky about jitter than others, and that will be accentuated when packets of many bytes are sent or received, scrunched together. Could that be it?

    XTAL1 alone will draw less current then XTAL1+PLL1, no change in performance. (about 1.0mA vs 1.7mA for a single cog) . Only need the PLL on if you want fastest transition in PLLx clock settings.
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