P2 Evaluation Board - Brief Update December 18th

123457»

Comments

  • Under Linux you can try screen (which should be available by default in most distributions) like:
    screen /dev/ttyUSB0 115200
    
    changing the device and speed (tried upto 960800 without issues)
    Stockholm, Sweden
    I am only an egg -- Stranger in a Strange land, Robert A. Heinlein
  • samuellsamuell Posts: 405
    edited 2019-01-16 - 01:37:07
    rosco_pc wrote: »
    Under Linux you can try screen (which should be available by default in most distributions) like:
    screen /dev/ttyUSB0 115200
    
    changing the device and speed (tried upto 960800 without issues)
    Yes, that works. Thanks! I guess PuTTY under Linux doesn't (properly) send the escape character.

    On another note, I accidentally shorted (I think) pin P14 momentarily to 5V, while probing it. I've heard a hiss, but strangely the pin is good (was still outputting the signal, as before, after the fact). I'll have to take measures to isolate the 5V pins that are sticking out. I hope I didn't damage the board. Anyway, I've read that the pins tan withstand 5V momentarily. Is that true?

    Also, I'm having inaccuracies regarding the frequency on seeming every pin. For instance, typing "4 PIN 10 MHZ" causes pin four to output a square wave having frequency around 2.855MHz. Any other frequency I select, on any other pin, will be inaccurate within the same factor.

    Update: The crystal is not enabled. I can't see any oscillation while probing the respective pins (or the probe capacitance is disturbing the oscillation, but TAQOZ is still runnable while probing the crystal, so it is unlikely that it is enabled). Maybe it is using RCFAST?

    Update 2: TAQOZ freezes or appears unresponsive when blinking pins 62 or 63. Typing "62 BLINK" freezes immediately, and the "ok" doesn't show up. Pin 62 also blinks erratically. Typing "63 BLINK" also causes the halt, but "ok" and the prompt are printed after the command. Pin 63 then blinks normally. Anyone can confirm this?

    Kind regards, Samuel Lourenço
  • samuell wrote: »
    Thanks! Strangely, I've only been able to access TAQOZ on Windows 10. The sequence was "> [esc]". I don't know why I'm unable to call TAQOZ on Linux, using PuTTY. Under Windows 10, both TeraTerm and PuTTY will work. Encoding issue?

    Anyway, already tested Peter's PWM example and it worked OK.

    Kind regards, Samuel Lourenço

    Using Minicom on Linux I had to turn flow control off for TAQOZ to work.
    samuell wrote: »
    Update: The crystal is not enabled. I can't see any oscillation while probing the respective pins (or the probe capacitance is disturbing the oscillation, but TAQOZ is still runnable while probing the crystal, so it is unlikely that it is enabled). Maybe it is using RCFAST?

    forums.parallax.com/discussion/comment/1460944/#Comment_1460944
    Bear in mind that with TAQOZ in ROM that it could only be tested in FPGA at 80MHz where we didn't know yet about the final clock details for silicon. So if we set a pin to 40 MHZ then it will output half the CPU clock which was assumed to be 80MHZ but RCFAST is more around 22MHz or so. This btw reveals the speed of RCFAST rather nicely since the pin will output RCFAST/2. The new version of TAQOZ knows all about how to set the clock and adjusts its timing accordingly.

    There are also functions in EXTEND which allow you to specify various clock configuration parameters so you can experiment interactively. You can do so safely if you work from the initial RCFAST, type in a line or a function and make sure that the last word to execute is RCFAST. Something like this:
    8 PIN 40 MHZ
    
    so that P8 is outputting half the CPU clock which you can monitor with a scope.
    15PF PLLEN 4 XIDIV 50 VCOMUL 1 PLLDIV USEXTAL 5 s RCFAST
    
    So that selects 15PF loading, XI divider of 4 = 5MHZ, 50 VCO multiplier (effectively) = 250MHZ, no PLL divide, then selects the external crystal as the CPU clock for 5 seconds before switching back to RCFAST and returning to the console.

    samuell wrote: »
    Update 2: TAQOZ freezes or appears unresponsive when blinking pins 62 or 63. Typing "62 BLINK" freezes immediately, and the "ok" doesn't show up. Pin 62 also blinks erratically. Typing "63 BLINK" also causes the halt, but "ok" and the prompt are printed after the command. Pin 63 then blinks normally. Anyone can confirm this?

    Kind regards, Samuel Lourenço
    Confirmed. Pins 62 and 63 are used for serial communications. Blinking those pins will naturally cause communication issues.
    James https://github.com/SaucySoliton/

    Invention is the Science of Laziness
  • Thanks SaucySoliton! By the way, I'm unable to change the timing source as described, but probably I'm doing something wrong.

    Kind regards, Samuel Lourenço

Sign In or Register to comment.