jugglingcats

Most recent activity

• Wired networking

  @jugglingcats started

  • 2 comments
  • 2,951 views

  @Gordon replied
• Wired networking

  in Interfacing • 5 years, 7 months

  

  Hi, we are interested in supporting wired networking (ethernet) on STM32 using the low-level ST ethernet driver package plus lwip (or similar). For example this might be on a nucleo board with built-in ethernet. Less interested in SPI or other add-on board solutions such as WIZnet.

  Has anyone achieved this, or have any helpful pointers on steps required to enable?

  Many thanks!

• Using timer(s) to capture multiple inputs

  @jugglingcats started

  • 13 comments
  • 6,030 views

  @allObjects replied
• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  After a lot of messing about and reading the spec, I don't think it's possible to have the counter DIR bit change according to a simple high/low on another GPIO as required. The encoder mode of the timer is designed for a quadrature encoder.

  I ended up with a little inline C to switch this bit according to GPIO input edge change like this:

  const native=E.compiledC(`
    // void dir(bool)
    unsigned char *addr=(unsigned char *) 0x40010000;
    void dir(bool state) {
      *addr = (*addr & ~0b00010000) | (state * 0b00010000);
    }
  `);
  
  setWatch(native.dir, B7, {repeat: true, edge: "both", irq: true});
  

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  I'd now like to go further and handle step and direction (with direction being high/low signal on another gpio). Having trouble understanding how to translate the example given below into Espruino equivalent!

  https://stackoverflow.com/questions/3294­7972/stm32-how-to-make-pulse-count-up-do­wn-with-timer

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  It just seemed to be easier to use 3 timers in the end because the register offsets are all the same, so I could write some generic code to initialise and read them etc.

  I've put all the code on Github...

  https://github.com/jugglingcats/pulse-co­unter

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  And the finished product :)

  https://photos.google.com/share/AF1QipPR­R2cNrgRcmrWyI4HYQjqYQHJCvi22RbPz4kFwCmBi­TjG5c9GRKKNgFqNskFPdOA/photo/AF1QipPRH14­PQnJI4hWbzgJOrvier7nkeSc7_Tai5fFm?key=Sk­ZiSmFIYVd6U0tQbE83NldmRU9wbUdjUHhURjlB

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  Nearly done...

  

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  I got it all working - thanks!

  Here is my code in case it's useful to anyone...

  var DEFS={
    TIM1: {
      base: 0x40010000,
      pin: A8
    },
    TIM3: {
      base: 0x40000400,
      pin: B4
    },
    TIM4: {
      base: 0x40000800,
      pin: B6
    }
  };
  
  function init(tim) {
    const def=DEFS[tim];
    if ( !def ) {
      throw "Invalid timer!";
    }
    const BASE=def.base;
    
    // slave mode control register
    var SMCR = BASE+0x0008;
    // event generation register
    var EGR = BASE+0x0014;
    // Capture compare mode register
    var CCMR1 = BASE+0x0018;
    // Capture/compare enable register
    var CCER = BASE+0x0020;
    // counter
    var CNT = BASE+0x0024;
    // prescaler
    var PSC = BASE+0x0028;
    // auto reload register
    var ARR = BASE+0x002C;
  
    // enable PWM on A8 (TIM1 CH1)
    analogWrite(def.pin,0.5,{freq:10});
    // CC1E = 0 (Turn channel 1 off)
    poke16(CCER, peek16(CCER) & ~1);
    // CC1S[1:0]=01 (rising edge), IC1F[7:4]=0 (no filter)
    poke16(CCMR1, (peek16(CCMR1) & ~0b11110011) | (0b00000001));
    // CC1P=0, CC1NP=0 (detect rising edge), CC1E[0] = 1 (Turn channel 1 on)
    poke16(CCER, peek16(CCER) & ~(0b1011) | (0b0001));
    // SMS[2:0]=111 (ext clock), TS[6:4]=101 (CH1 as trigger)
    poke16(SMCR, (peek16(SMCR) & ~0b1110111) | 0b1010111);
    // Prescaler to 0 - use every transition
    poke16(PSC, 0);
    // auto-reload with the full range of values
    poke16(ARR, 65535);
    // poke the UG[0] bit to reset the counter and update the prescaler
    poke16(EGR, 1);
  
    return {
      get: function() {
        return peek16(CNT);
      },
      reset: function() {
        poke16(CNT, 0);
      }
    };
  }
  
  const TIM1=init("TIM1");
  const TIM4=init("TIM4");
  const TIM3=init("TIM3");
  
  function update(){
    g.clear();
    g.drawString("Steps X: "+TIM1.get(), 2, 2);
    g.drawString("Steps Y: "+TIM4.get(), 2, 20);
    g.drawString("Steps Z: "+TIM3.get(), 2, 38);
    g.flip(); 
  }
  
  // SPI
  var s = new SPI();
  s.setup({mosi: B15 /* D1 */, sck:B13 /* D0 */});
  var g = require("SH1106").connectSPI(s, B14 /* DC */, B10 /* RST - can leave as undefined */, function() {
    setInterval(update, 100);
  });
  
  setWatch(function(e) {
    TIM1.reset();
    TIM4.reset();
    TIM3.reset();
  }, BTN, { repeat: true });
  

• Using timer(s) to capture multiple inputs

  in Interfacing • 6 years, 1 month

  

  That's helpful Gordon thanks. Yes I am using the Pico.

  So you think if I pick, say B6 and B7 (TIM4, CH1 and CH2 respectively), I should be able to do the same trick as you did with TIM1, just by looking up the relevant register addresses/offsets?