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1  Community / Website and Forum / Re: post count in base what? on: June 03, 2014, 04:59:57 pm
Been there, done that smiley-wink

Google 1337 or LEET.
Leet is short for "elite" and is supposed to be used to point out someone is doing a good job or has reached a certain level.
It's a bit of a joke, either by the admin or by the forum software team.

wow!
2  Community / Website and Forum / post count in base what? on: June 03, 2014, 03:15:02 pm
see picture
my post count is now "leet" or possibly "1eet"
either way, not a radix with which I am overly familiar?!?
smiley


since this is now post 1338, I'm guessing the picture was post 1337 (if that helps, at all, slightly, a bit!)
3  Using Arduino / Networking, Protocols, and Devices / Re: Software serial into serial port on: June 03, 2014, 03:10:54 pm
USB is defined, wikipedia has a nice article.
Basically its like RS485, two twisted pair lines at +/-3V levels if I recall.
Master sends, slave responds, there's some other negotiation stuff that goes on that the FT232 and 16U2 as USB/Serial adapter take care of.
Very high speed - 12 Mbits/sec for "slow" transfers, up to 400+ Mbits/sec for fast transfers.
ah!
ok I give in
direct connection to D0, D1 it is
thanks all for assistance smiley
4  Using Arduino / Networking, Protocols, and Devices / Re: Software serial into serial port on: June 03, 2014, 12:51:07 pm
Quote
USB is not RS232
I think you meant to say USB is not TTL (0-5V signals).
I agree D11/D12 to D0/D1 direct (or D12/D11 to D0/D1, whatever completes the Rx to Tx and Tx to Rx paths.
the ideal would be for soft serial out (D11 and D12 to be able to generate signals that FT232 could read

you say that USB signals are NOT TTL?
is it just the voltages that are different
- if so, what voltages does USB use
- if not, do you (anyone) have a definition of the protocol?

thanks smiley
5  Using Arduino / Networking, Protocols, and Devices / Re: Software serial into serial port on: June 02, 2014, 04:55:51 pm
That's a shame, I really wanted to connect through the FT232RL chip
What is different? And more important, is it fixable?
Cheers
6  Using Arduino / Networking, Protocols, and Devices / Software serial into serial port on: June 01, 2014, 01:56:30 am
My project uses several own-brew Arduino boards
Master is connected to PC as normal
It talks, using software serial, to the first slave, which then talks to next slave and so on
Software serial out is using D11 and D12
If I connect master directly to D0 and D1 on slave, everything works perfectly

If I connect master to the USB serial port on the slave, nothing happens
I have assumed that the voltage levels are ok and that the signal /data is the same
So what did I miss?

I tried swapping D11 and D12 in case I had them the wrong way round
Any ideas?
Thanks
Mike

PS my serial port uses a FT232RL chip
7  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 22, 2014, 03:17:29 am
hmm interesting follow up
I made up some proper boards rather than the breadboard with wires all over the place
slightly different MOSFET
LEDs now behaving as expected
mebbe it was a duff MOSFET after all
anyway happy bunny again smiley
thanks to all
8  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 15, 2014, 09:05:10 am
I found the problem
it's not the circuit or software per se
it all works 100% into a resistive load

the LEDs I am using have all sorts of extra circuitry which presents as a capacitive load
the FET is turning on and off as expected

the LEDs are just holding some sort of charge

so me all happy now I understand smiley
9  Using Arduino / Programming Questions / Re: timer not behaving as expected on: May 13, 2014, 01:41:13 pm
Agreed that you need "volatile".

I don't see a problem with how you've programmed the timer, and changing OCR2A should certainly affect the frequency of the interrupts. However, with a prescaler of 1 and OCR2A = 1, there isn't enough time to service each timer interrupt. Try prescaler = 128 or something, so you can verify that everything else is working.
ah that makes sense
I changed to volatile and it didn't make any difference
I'll try your suggestion
trouble is I think it'll slow everything down too much smiley-sad
10  Using Arduino / Programming Questions / timer not behaving as expected on: May 13, 2014, 12:47:38 pm
I'm trying to implement my own (finer-grained) PWM

here's the code so far:
Code:
//=========
//timerTest
//=========

int counter = 0;

int pwm = 0;
int pwmMax = 20;

#define LEDPIN 10

boolean once = false;

void setup()
{
 
  //set pin as output
  //=================
  pinMode(LEDPIN, OUTPUT);

}

void mySetup(void)
{
  // stop interrupts
  //================
  cli();

  //set timer2 interrupts
  //=====================
  TCCR2A = 0;
  TCCR2B = 0;
  TCNT2  = 0;
 
  // set compare match register
  // for number of increments
  //===========================
  OCR2A = 1;            // changing this seems to have no effect

  // turn on CTC mode
  //=================
  TCCR2A |= _BV(WGM21);

  // Set prescaler
  //==============
  TCCR2B |= _BV(CS20);

  // enable timer compare interrupt
  //===============================
  TIMSK2 |= (1 << OCIE2A);

  //allow interrupts
  //================
  sei();
}

ISR(TIMER2_COMPA_vect)
{
  counter++;
  if (counter > pwmMax)
  {
   counter = 0;
 
   if (counter < pwm && pwm > 0)
      digitalWrite(LEDPIN, HIGH);
  }
 
  if (counter >= pwm)
    digitalWrite(LEDPIN, LOW); 
}

void loop()
{
  int i;

  if (!once)
  {
    mySetup();
    once = true;
  } 
 
  for (i=0; i<pwmMax; i++)
  {
    pwm++;
    delay(2000);
  }
  for (i=0; i<pwmMax; i++)
  {
    pwm--;
    delay(2000);
  }
}

it almost works in that it does spit out a PWM signal on the required pin
but ...
a) it seems to effect how delay(2000) works - far less than two seconds
b) altering the line with OCR2A= seems to make no difference

what I want to achieve is
a) prescaler of 1
b) PWM frequency > 1 kHz
c) range of 0 - 1023 or better still 0-2048

what did I miss?

cheers
Mike
11  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 02, 2014, 02:03:11 am
pins 5 & 6 are driving one LED array each
PWM signal is fine

simple sketch does the business
Code:
void setup(void)
{
  analogWrite(5, 128);
}

void loop(void)
{
}
12  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 01, 2014, 10:10:54 am
@dlloyd
yup the signal is inverted as you describe

maybe I just stop looking at the scope
the MOSFET is stone cold
the LED brightness is changing
can get too picky I suppose smiley

cheers
Mike
13  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 01, 2014, 10:07:37 am
What are important when illuminating a fish tank?

A smooth dimming of the LEDs ?
A perfect square voltage drivning the LEDs?

Have you checked if the CURRENT are perfect square?

I think you have a nonproblem. If the MOS were burning hot there was a problem.

Pelle

I suspect you are right
the smoothing of dimming is under control
I just analogWrite a different value

what started me down this trail it that from 255 down to 1 the LEDs change almost imperceptibly - a good thing
the drop from 1 to 0 is quite noticeable
that's when the scope came out and the questions started

maybe I just live with it smiley
14  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 01, 2014, 09:04:35 am
@Tom
the complete sketch is HUGE as it's only one corner of the project
the bit that's relevant is that the driving signal is a PWM signal from pin 5, to an optocoupler, thence to the circuitry
15  Using Arduino / General Electronics / Re: oh no not P-channel MOSFETs again! on: May 01, 2014, 09:03:27 am
no link but it is a commercial fish tank luminaire
a quick eyeball (surprising really - it has a glass cover smiley
aside from the LEDs I can see a couple of passives for each, a diode across the voltage in, and a couple of chips labelled
C11
J112G
and an Omicron logo

at one of the earlier poster (scrolled off screen now)
I don't think the FET turning OFF is the issue, it's the LED array refusing to lie down when told smiley
using quite a low resistor, the waveform is perfectly sharp smiley

that's what's drawing me to a 2nd MOSFET
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