wight catchup

Flashlight Modding and DIY Parts
34

Welcome back!

Schoki has made a boost driver that will be very interesting once Lexel gets it running and on sale… :partying_face:

35

That is putting it very politely.

Flintrock disappeared quite a while ago, but whilst he was here, he had, lets say, a high opinion of his abilities, and derision for almost every one else who questioned some things.

And his code was, let’s just say, unusual.

36

I think I fixed the OTC design some years ago and made it consistent, defined, analysable. Instead of a capacitor just dangling in the breeze.

But it seemed nobody at the time was interested. Or perhaps felt threatened.

I could discuss, but only in PM.

37

Hmmm… I wonder if Flintrock ever thought about coming back under a different name and trying to build a different reputation for himself…

:disguised_face:

I’ve heard it can be done. :wink:

38

The code supporting OTSM was tricky mostly because it relied on bare interrupts running raw assembly code. This made it extremely hardware-specific, and it also appears to have made the code buggy in some pretty unpredictable ways. I think perhaps the bare interrupts were less safe than Flintrock had thought, and may have had subtle unintended effects, but I haven’t tested to verify that. I just know that, whenever I tried BistroHD on real hardware, it exhibited a pretty wide variety of issues which were not easy to reproduce on purpose.

I’ve been trying to push code in the opposite direction instead — making it less hardware-specific and more portable, so people can mix and match whatever hardware they want with whatever UI they want. And for that, I think it’s about time to support more than one MCU architecture. I’m not sure which one to add next, but I’m thinking maybe tiny84 or tiny841 or tiny1634. New driver designs frequently seem to need more pins, and I have a bad habit of filling space, so it wouldn’t hurt to have more ROM too.

39

I agree, a new MCU is needed, something with both more pins and rom space.

I am also very grateful for the move to more universal firmware setup, now that I have started to play with Anduril I am seeing the flexability, I just need to figure out what the limits are. I tend to push past the bounds unless I know exactly where they are.

40

OTSM is absolutely reliable, pretty simple to handle, no "raw assembly code" required! This is the proof-of-concept code I sent to Mike C on request almost 2 years ago. I would have given it to anyone here who had asked but sadly there was no interest.

Try it!

/* Simple sample firmware for otc less design (single cell).

Half press less than about 300 ms: next mode

between 300 and 900 ms: previous mode

longer:                 blink out voltage reading

(0 to 255) in 3 decimals


Suggested capacity of buffer cap (C2): >= 47 uF.

Vbatt is connected to PB3 (Pin2).

Voltage divider still connected to Pin7.

Timing specified for Attiny25 at 10 Mhz.

Don't fuse BOD.

Created and built with Atmel Studio.

Fuses for Attiny25: lfuse: 0xD2, hfuse: 0xDF.

*/


#include <avr/interrupt.h>

#include <avr/sleep.h>

#include <avr/wdt.h>


#define PIN_7135            PB0

#define PIN_FET             PB1

#define PIN_POWER_DETECT    PB3

#define INT_POWER_DETECT    PCINT3

#define VLT_PIN             PB2

#define VLT_CHANNEL         0x01

#define VLT_DIDR            ADC1D

#define ADC_VREF            ((1 << REFS1) | (1 << REFS2))    // 2.56V

#define ADC_PRESCL          0x06


#define PWM_PHASE           0xA1

#define PWM_7135            OCR0A

#define PWM_FET             OCR0B


#define MODE_COUNT          6

#define PWM_LEVELS_7135     30, 80, 255, 255, 255,   0

#define PWM_LEVELS_FET      0,   0,   0,  30,  80, 255


// forward declarations

uint8_t adc_init_and_read();

void blink_once();

void blink_once_long();

void blink_value(uint8_t value);

void delay_250_micro_sec(uint8_t n);

void delay_50_milli_sec(uint8_t n);

void delay_1_sec();

void led_off();

void led_on();


volatile uint8_t s_clicked = 0;

const uint8_t pwm_levels_7135[] = { PWM_LEVELS_7135 };

const uint8_t pwm_levels_fet[] = { PWM_LEVELS_FET };

uint8_t mode_index = 0;


////////////////////////////////////////////////////////////////////////////////


int main(void)

{

uint8_t blink_voltage = 0;

uint8_t voltage;


// set LED ports as output
DDRB = (1 &lt;&lt; PIN_7135) | (1 &lt;&lt; PIN_FET);

// initialize PWM
TCCR0A = PWM_PHASE;
TCCR0B = 0x01;

// enable pin change interrupts
PCMSK = (1 &lt;&lt; INT_POWER_DETECT);
GIMSK |= (1 &lt;&lt; PCIE);
sei();

// start with first mode
PWM_7135 = pwm_levels_7135[mode_index];
PWM_FET = pwm_levels_fet[mode_index];

while ( 1 )
{
    if ( s_clicked )
    {
        if ( s_clicked &lt;= 10 ) // &lt; about 300 ms
        {
            blink_voltage = 0;
            mode_index++;
            if ( mode_index &gt;= MODE_COUNT )
                mode_index = 0;
        }
        else if ( s_clicked &lt;= 30 ) // &lt; about 900 ms
        {
            blink_voltage = 0;
            mode_index--;
            if  ( mode_index == 255 )
                mode_index = MODE_COUNT - 1;
        }
        else // &gt; about 900 ms
        {
            mode_index = 0;
            blink_voltage = 1;
        }
        
        s_clicked = 0;
        PWM_7135 = pwm_levels_7135[mode_index];
        PWM_FET  = pwm_levels_fet[mode_index];
    }
            
    voltage = adc_init_and_read();
    
    if ( blink_voltage )
        blink_value(voltage);
    
    delay_1_sec();
}



}


////////////////////////////////////////////////////////////////////////////////


ISR(PCINT0_vect)

{

// disable output

PORTB = 0;


// turn off PWM generation (might not be necessary)
TCCR0A = 0;
TCCR0B = 0;

// ADC off
ADCSRA &amp;= ~(1 &lt;&lt; ADEN);

// disable pin change interrupt
GIMSK &amp;= ~(1 &lt;&lt; PCIE);
PCMSK = 0;

s_clicked = 0;
set_sleep_mode(SLEEP_MODE_PWR_DOWN);

do
{
    s_clicked++;
    
    wdt_reset();
    WDTCR = (1&lt;&lt;WDIE) | WDTO_30MS;

    sei();
    sleep_mode();
    cli();
    
} while ( (PINB &amp; (1 &lt;&lt; PIN_POWER_DETECT)) == 0 );

wdt_disable();

// debounce
delay_250_micro_sec(10); 

// activate pwm generation
TCCR0A = PWM_PHASE;
TCCR0B = 0x01;

// enable pin change interrupts
PCMSK = (1 &lt;&lt; INT_POWER_DETECT);
GIMSK |= (1 &lt;&lt; PCIE);



}


////////////////////////////////////////////////////////////////////////////////


void delay_250_micro_sec(uint8_t n)

{

while ( n-- )

{

int k = 180;

while ( k-- )

{

if ( s_clicked )

return;

}

}

}


////////////////////////////////////////////////////////////////////////////////


void  delay_50_milli_sec(uint8_t n)

{

do

{

delay_250_micro_sec(200);

if ( s_clicked )

return;

} while ( --n );

}


////////////////////////////////////////////////////////////////////////////////


void delay_1_sec()

{

delay_50_milli_sec(20);

}


////////////////////////////////////////////////////////////////////////////////


void led_on()

{

PWM_7135 = pwm_levels_7135[mode_index];

PWM_FET  = pwm_levels_fet[mode_index];

}


////////////////////////////////////////////////////////////////////////////////


void led_off()

{

PWM_7135 = 0;

PWM_FET = 0;

}


////////////////////////////////////////////////////////////////////////////////


void blink_once()

{

led_on();

delay_50_milli_sec(5);

led_off();

delay_50_milli_sec(5);

}


////////////////////////////////////////////////////////////////////////////////


void blink_once_long()

{

led_on();

delay_1_sec();

led_off();

delay_1_sec();

}


////////////////////////////////////////////////////////////////////////////////


void blink_once_short()

{

led_on();

delay_50_milli_sec(1);

led_off();

delay_50_milli_sec(5);

}


////////////////////////////////////////////////////////////////////////////////


void blink_value(uint8_t value)

{

// 100er

if ( value < 100 )

blink_once_short();


while ( value &gt;= 100 )
{
    value -= 100;
    blink_once();
}
delay_1_sec();

// 10er
if ( value &lt; 10 )
    blink_once_short();

while ( value &gt;= 10 )
{
    value -= 10;
    blink_once();
}
delay_1_sec();

// 1er
if ( value == 0 )
    blink_once_short();

while ( value &gt; 0 )
{
    value--;
    blink_once();
}
delay_1_sec();



}


////////////////////////////////////////////////////////////////////////////////


uint8_t adc_read()

{

uint8_t value;


while (ADCSRA &amp; (1 &lt;&lt; ADSC))
{
    if ( s_clicked )
        return 0;
}
value = ADCH;
ADCSRA |= (1 &lt;&lt; ADSC);
return value;



}


////////////////////////////////////////////////////////////////////////////////


uint8_t adc_init_and_read()

{

DIDR0 |= (1 << VLT_DIDR);

ADMUX  = ADC_VREF | (1 << ADLAR) | VLT_CHANNEL;

ADCSRA = (1 << ADEN) | (1 << ADSC) | ADC_PRESCL;

adc_read(); // first run not reliable (see spec)

return adc_read();

}


////////////////////////////////////////////////////////////////////////////////

// empty interrupt function required otherwise mcu will reset


ISR(WDT_vect)

{

};


////////////////////////////////////////////////////////////////////////////////

41

Oh, nice. I didn’t know anyone except Flintrock had done it. This is much more useful, and demonstrates a pretty clean way to do it. It would not have occurred to me to go to sleep inside an interrupt handler.

Could I add this to the repository?

42

A legend returns! Welcome back wight. Even though I joined after the start of your “sabbatical”, it seems like I’ve read (and re-read) so many of your posts. Thanks for your contributions thus far.

43

Also a welcome back. Heard quite a bit about you. I keep following along.

44

Good to have you back wight.

45

Yes.

46

In no particular order:

Thanks for the welcome back & for the flashlight & lantern links!

To all the folks who showed up during my hiatus: welcome to BLF :stuck_out_tongue: I’m thrilled to think that anything I posted was still of use while I was away.

To all the folks who were already here - it’s really nice to see that you folks are still kicking!

I think that you’re confusing my builds with yours. :wink:

There are several obstacles besides dangling. IIRC the ATtiny25/45/85 thread contains some work trying to compensate for temp & voltage. For 1s lights the voltage divider may no longer create a problem for the OTC, but for 2s lights w/ a Zener or LDO there will still be a voltage divider messing with drain on the OTC. I generally prefer to discuss things out in the open so that everyone can benefit, but with that said sometimes it’s easier to get the ball rolling in PM. Feel free to drop me a PM where we can get our thoughts together.

The capacitor recommended by Flintrock for the OTSM solution is expensive and it would certainly be nice to avoid it!

Thank you for sharing the PoC! Hopefully the idea will get more traction now with a compact demo available. :laughing: I don’t have a 25/45 right now, only 85, so I won’t be able to try it right away. I’ll try and pick up the necessary bits on my next parts order. Did you or Mike C look into component selection? Flintrock recommended a $1/ea capacitor w/ legs which looked troublesome for hand soldering/rework. A bulletproof offtime solution is worth $1, but less expensive is always appreciated, especially if anyone mass-produce a driver using this technique.

Boaz caught me. It was I who released that scourge upon the world. When my secret finally leaked I couldn’t face the forum for years! :stuck_out_tongue: :stuck_out_tongue:

The truth is that this was actually the situation long before I left. :open_mouth: Still, there is a lot of bang-for-the-buck (as well as satisfaction) to be had with reasonable custom builds or customized budget lights.

Thanks TA, I’m glad that you carried to torch! I hope that I’ll do some cooking, but no promises on that front. Step 1: build a couple of working flashlights out of my piles of supplies.

Right now I’ve got to get my work space up to snuff. In the intervening years since I left the forum my flashlight stuff has been packed, repacked, moved, etc. I’ve got a new hobby area now but it’s been in use for (and is currently in use for) other projects. So in other words… right this moment I should stop reading forum threads and go clean up! :smiley:

47

I built my last OTSM drivers in early 2017 (focused on momentary switches now) and couldn’t find any notes :person_facepalming: so had to open a S2+ triple with this driver and see what I’ve used:

Found 2 added ordinary 100uF X5R ceramic caps, connected to GND and Vcc of mcu. I measured them about 160 uf together. The driver is a BLF X6 with Attiny25. But beware the BLF X6, there was a batch with reprogramming locked by fuse. I don’t know if Banggood made a change afterwards, I haven’t bought this driver since that time.

Btw - why do you think you can’t use the Attiny85?

48

I think they fixed it. As soon as I heard about it I sent a pretty strongly-worded message that they shouldn’t do that, for a handful of different reasons, including legal reasons (locking it violates the code license).

Some relevant parts of the license…

49

Flintrock’s OTSMC Build Instructions say so, see my excerpt below. (My 85’s will be 5 years old next month.) Thanks for cracking open your build to share the info/pics with us. What gauge magnet wire (enamel wire) do you use? I keep meaning to order some but then I’m indecisive about what gauge to get. I think that 30awg is thin enough to be a pain, maybe 26awg?

50

As you can see in my code, I haven’t used this BODS option at all. I’ve checked all my Attiny25 that time and there wasn’t a single one supporting BDOS. Its a pity that I don’t even remember why I used such a high capacitance of 200 uF, might be because I wanted to be on the save side with lowest voltages, or because I fused BOD even without the BODS option. Can’t read the fuses now since I locked that mcus after programming :person_facepalming: .
Anyway - I’m pretty sure your Attiny85 will work with OTSM and my code, at least without fusing BOD.

Regarding the wire: I’ve bought it decades ago, I guess at my local electronics store. I used it for my commercial prototypes that time. Unfortunately there are no specifications on the roll, only the price tag: 2.90 DM. This currency doesn’t even exist any more.
My caliper measures about 0.2 mm in diameter, including insulation, nevertheless this wire is pretty tough.

51

I also found a fix for OTC, odd but works

2S lights with buck or boost have caps making the OTSM tricky or impossible
Solution flash 1S firmware 1uF capacitor with 680kOhms in parallel

The key is to get the drain of the OTC decoupled by thermal variable self discharge which raises a lot on higher temperatures, also using X7 or even X8 caps in bigger physical size like 0805 which are a bit less temperature sensitive

52

I have tested and sold about 100 OTSM drivers with a differet cheaper 50 cents capacitor, basically the good infineon FET and MCU make about 2/3 of the parts costs of FET+1 driver design

Still the OTSM firmware on some revisions caused me problems and possible some hidden bugs still present

53

A cap is just a cap. In this application. Really. There is no special magic, and obviously the cheaper the better, as long as they are good. And store energy reliably.

BTW, other things can also do that nowadays, maybe better, and might be worth looking at.

Whether 100 uF is the right value, I don’t know, but it is a nice round number.

Bye the way, Flashy Mike has just posted some OTSM code that looks interesting. It is beyond my abilities to venture an opinion, but it already looks much more plausible than Flintrock ever managed.