[UPDATE:v1.7.1,Q8&1chanOTSM]bistro-HD, bistro your way. OTSM, eswitch(devel), Vcc reads, safe_presses, turbo timeout...

Flashlight Modding and DIY Parts
65

I have two bugs/typos. That's good because it solves problems. One in particular may explain a bunch, certainly should break OTC in the original post. The error is

PORTB=~DDRB;

should be

PORTB|=~DDRB;

The difference is the first one disables OTC cap charging, which meant OTC builds probably didn't change modes at all, oops. I was only testing with OTSM at the end.

The other bug is

#define OPT_firstboot (EEPSIZE-1)

should be

#define OPT_firstboot (EEPSIZE-8)

could cause interference between reset toggle and muggle mode toggle. I'll probably post a bug-fix only build shortly, but I'm working on a much overhauled version with all new bugs ;) .. and need to get some of those sorted out, the ones I know about at least.

The OTC bug, may well explain the OTSM problems, as it means the OTC pin was floating, which can drain power during sleep, in random ways. It might explain it, or might not.

66

Well that did get the driver working properly in a normal OTC build, but it didn't solve the OTSM bug and in fact that code path wasn't relevant for OTSM. This really seems to be a hardware issue and is a mystery still.

67

At lexel, I've been working on a manual to go with the next release. This is a good process because it makes one think through things. I realized that actually you should get the behaviour you want just by building an e-switch only build, no OTSM or OTC enabled, preferably no off-time cap on the board. The clicking switch will obviously always "work" no matter what configuration you use. In e-switch-only, with a standard small C2 cap, the click time will always default to a long press on a full power-off.

If you don't use memory mode this means it will reset to the first mode, so you'd just want to setup the first mode as your signaling brightness. Or, you could turn on mode memory, and it will just always stay in the last mode, and you can signal in whatever brightness you want.

Normally many fast presses hit the menu, but that won't happen, because they will get interpretted as long presses. Only the e-switch will be able to access the menu.

Big new release coming soon with lots of good stuff, but I hope it's a little better tested this time (still will have much that isn't too though). I'll try to remember to include an e-switch only build for you.

68

Updated OP with new version.

Lots of new stuff including many build configurations (that you can pattern new ones off of) especially for all the bistro variants. Especially, it has a biscotti-HD build included with all the latest space savings and as a result some added features (specifically a more stable noinit method, and (untested) turbo timeout/bump-up, and room for you to configure in a couple more yet. More especially, at least some of it works this time. The TAv1-OTC hex and its battcheck are pretty well tested on attiny25 (everything except thermal calibration, haven't really tried to test that closely, but never messed with it much either).

I wanted to get the universal concept really flushed out and a bit more stable (many of the space savings techniques resulted in a bunch of changes to iron out) before pushing forward with advancing new features too much more, although there are some new ones.

69

OTSM is fixed. (OP updated) and is working perfectly on a TAv1 17mm light. I don't see any reason this shouldn't become the default setup for these lights. It's just so much better than OTC. As this TAv1-OTSM build is now really (was always meant to be) the flagship HD build, maybe I need a new name for it.

Below are some details about how to build it, also found in the Manual and the OP. In the end this worked so well that it's likely possible to cut some corners, like use cheaper ceramic caps. Personally I probably just wouldn't, but it may work fine.

VIII.1 Parts and build for tested TAv1 board

OTSM is working better and better, but getting it there required a combination
of software work and the best parts. It may be possible now to use cheaper or
lesser parts since OTSM performs a little better than needed with these, but
these are tested and work.

MCU:
It's required to have BODS support for the mcu (see theory below). From page 36
of the manual this requires:
• ATtiny25, revision E, and newer
• ATtiny45, revision D, and newer
• ATtiny85, revision C, and newer

[This note not in manual yet: Revision letter is lower left most letter on bottom of Attiny 25. I forgot on attiny 45 where it is, might be on top.]

The spec for OTSM also requires V version (10Mhz, low voltage version) chips.
You might get by without it, but it won't work as well and may cause
corruption.

Unfortunately most ATtiny 85s reported off the shelf have been revion B, for
the past many years even. They don't work. So far Attiny25, attiny25V,
attiny45 and attiny45 v's where reports exist on this, have been of recent
enough version. Of course attiny25V is available in the smaller footprint and
fits 17mm TAv1 boards. At the time of this writing all HD features including
OTSM can fit on an attiny25.


Diode part number: RB751V40T1G
http://www.onsemi.com/pub/Collateral/RB751V40T1-D.PDF

This is the MCU protection diode. It isolates voltage from the C2 cap that
powers the MCU while input power is down. It was chosen for its low leakage
even at high temperatures. Leakage below 1 or 2 uA is probably fine.

C2 cap (powers MCU during off time, quality counts here)

Cap part number: 298D476X0010P2T
http://www.vishay.com/docs/40065/298d298w.pdf

This cap was chosen to get the most capacitance in an 0805 possible and because
Tantalum does not suffer from DC bias de-rating or temperature fluctuation.
Capacitance this high (47uF) in an 0805 are all low voltage. For Ceramic if
the DC offset is more than about 1/3 of the rated voltage the capacitance
starts to drop, some times a bunch. This cap does have a large tolerance
though unfortunately.

Voltage divider:

Tested with R1 of 1K and R2 of 3.3K R1 should be no more than about 1/3 of R2,
but this ratio should be ideal for OTSM performance in a 1S light (but only in
a 1S light). Lower values can improve OTSM performance, at the expense of
higher mood mode drain. If you use lower quality caps or diode, you can try to
add a bleeder of about 500ohm to gain a little advantage on off time, not much.

OTC:
None, unpopulated.

C1: 1uF (see TA instructions for part numbers)

For all other parts, see the Texas Avenger instructions.

70

I haven't had a chance to read in detail yet, but this sure seems like some really exciting stuff you're doing here Flintrock.

71

Click click, whoo.. lol. Fun at least. Don't forget Mice C and flashy mike who took the early talk is cheap attitude to get this all going.

72

Version 1.1 posted (see OP)

Includes firmware for an LDO OTSM TA build. Latest Build instructions will be maintained in the Manual, and the OP, but the excerpt is below.

Also split the dual switch build into a noinit version and an OTSM version. The OTSM version is specifically targeted at lexel's "option 3", but an option 1 configuration should arrive soon.

These are not tested builds/firmwares, but the differences from the regular OTSM versions are fairly straightforward and those differences have each been independently tested. The LDO build should work. Dual switch, enh, probably. No guarantee or implied anything.

VIII.1b Parts and build for TAv1 board for LDO (2S, 3S etc)

Quick version:
See section VIII.1a for mcu, cap and diode selection.
Place the diode on the R7 resistor pad with the anode (+ side) pointing away
from C2. No OTC cap is needed. Use the following divider resistors, in ohms.

R1 R2
2S: 1780 2210
3S: 2250 1500
4S: 2870 1100

Should be 1% or better. Dropping R2 by 1% or 2% might help get full range of voltage read on the very top end and the risk of pushing the specs slightly at the low end. Not a big deal either way. The default calibration is centered around the values above though.

No bleeder. That's it.

For all other parts, stick with the original Texas Avenger instructions.

Long version:

For 2S or more build, the attiny must be fed power by some form of voltage
regulation such an LDO. This means that Vcc (input voltage) cannot be used to
measure the battery voltage. The divider must be used. Furthermore because
the divider pin must stay logic high to indicate power on, the 1.1V reference
cannot be used. The REFERENCE_DIVIDER_READS_TO_VCC option must be used (It's
compiled into the LDO firmware) This reads pin voltage as a fraction of Vcc
with Vcc being the max, allowing the highest possible divider voltages.

There's some difficulty here because a low battery, 2.5V/cell is 0.6 the
voltage of a full battery: 4.2V/cell. 0.6Vcc is also the maximum trigger level
for a pin change interrupt, which indicates a click and puts the light into
sleep. In reality the trigger level should be below this, but by spec it can be
this high. So we need the divider voltage to really stay as high as possible.
Furhtermore Vcc is reduced from the LDO voltage by the diode voltage. This
fluctuates slightly with temperature and current, so we need to estimate this
max voltage as well as possible. From the diode spec sheet a maximum diode
voltage of about 0.4V at 2 to 4mA is seen, but more typical is 0.35V and this
should be correct within 0.1V even when hot.

Parts:
Using a TA generation 1 (v1) LDO board, a diode must be added, the same one as
for the 1S configuration above. The diode can be added in place of the R7
0-ohm resistor. The same caps are used as for the 1S OTSM version.

The only other difference is the correct resistor values should be chosen. We
want a total resistance R2+R1= about 4kOhms. We need the voltage on pin 7 to be
equal to the LDO voltage minus the diode voltage, ie Vcc, when the batteries
are at max voltage, Vbm.

So the divider should be R2/(R1+R2) = Vcc/Vbm.
Following the TA build specs and the diode used here, Vcc is 5.0-0.35 = 4.65V

This gives R2 = Vcc/Vbm *4kOhm.
And R1 = 4kOhm-R2

here is the calculated table for various voltage levels:
R1 R2 Vcc/Vbm ideal:
2S: 1786 2214 0.5536
3S: 2524 1476 0.3690
4s: 2892 1107 0.2768

Of course these resistors don't exist, so we need to look for something close,
with the ratio being the most important thing.

R1 R2 Divider Error %
2S: 1780 2210 0.06
3S: 2250 1500 0.36
4S: 2870 1100 0.1

These should be in 1% tolerance or better. Any inaccuracy here pushes the
measureable voltage range up against the spec limits.

73

:+1:

74

So, please humor me… It looks to me like a normal AT25 driver such as the X6 driver could be converted to OTSM if the OTC was removed? Or am I making this way to simple?

75

You mean attiny25? I'd have to consider case by case, (lots of the details are explained in the manual). But generally it should be possible to convert one, so long as there's a place to put a diode between the voltage divider and the mcu input bypass cap and so long as the input bypass cap is at least an 0603 footprint (there may always be ways to squeeze past these rules with enough hacking/squeezing).

No, just removing OTC isn't enough. You need to follow the full parts selection above for diode, mcu bypass cap ("C2"), and divider resistors. I should make it more clear but the diode and cap for the LDO lights are the same as for the 1S. I also forgot to point out that the anode of the diode (+) should point away from C2, but I guess that's obvious. I'll add a picture shortly. You can surely find other components than the ones I found that will work. I've gotten tests working with very different resistor combinations too (for 1S, LDO has pretty strict requirements there), but not just anything will work, and you can be pretty sure the original parts won't work. The ones I list are what I know works. They probably aren't the cheapest, but figuring out how best to cut corners wasn't my goal.

I still need to stop and remember the issues with lighted tailcaps, if there are any issues.

76

Oh at the moment I don't know any way to make this work on a zener driver, not without replacing the zener with an ldo at least. The LDO is needed for the LVP voltage reference.

77

I’ve been trying to plow through all this information. It’s been a struggle but I know that if I keep at it I’ll eventually get it:)

It would be great if someone could write do a write up of the process. Kind of like comfrchair did here. That’s the thread that really got me going. Basically go through an example build and take photos/screen shots along the way. This is asking a lot though. And most who are capable of this have already done so much. It would be helpful though…

Thanks for all your efforts!!!

78

Hi lightbringer. Let me know what you're trying to do and I'll walk you through it. I will try to add picture of TA's boards to explain which things to change. Using a specific example, it's very simple. the instructions above are such examples, and apply directly to his boards. Just change C2, R1, R2, and the diode (and the OTC, well the lack of it) exactly according to what's said there. That's it. And flash the 1S hex for 1S or the LDO hex for regulated mcu input.

If you're trying to get a different driver board working or there's something you don't get there, just let me know. I added a bunch of background to the instructions so that people can extrapolate to new scenarios, but if you just follow the component list for the basic TA boards, you should be fine.

I'm pretty interested in getting something working on your dual switch Supfire A2, but that stuff is much more experimental right now.

79

@mattlward, I almost forgot, it's also highly recommended to change out the mcu to a V version, either attiny25 or attiny45. See post 69 above.

80

Ok. I haven’t actually started something yet as I’ve not been confident enough. It’s good to know there will be help available for when I jump in:)

Supfire A2 dual switch? The a2 is single e-switch…

81

Oh I guess I got confused on the supfire. Well I like it anyway, and eswitch bistro still looks good for it to me.

yeah. I can't promise tons of time, but what you're asking is easy. Really there's nothing harder about this than building the normal TA setup. It's just a different component list. That's all, and while maybe I didn't write list clearly, those components are known now, so just have to buy the right ones and solder them on the right place. That's it. So sure, I can help with that, and any bugs that show up I hope, although in the basic OTSM build, I'm not seeing any.

82

I updated the LDO post (post 72) with a short version, hopefully it makes it a little more clear.

83

Awesome, awesome, awesome!

In VIII OTSM of the manual you say,

"The spec for OTSM also requires V version (10Mhz, low voltage version) chips. You might get by without it, but it won't work as well and may cause corruption."

I guess I need new chips . All the 25's I have from MTN are the 20SSU "high voltage" variations.

84

RH you can try it. I'd recommend reducing the divider resistors to 500ohm total or adding a 500ohm bleeder, and don't cut corners on the cap. To be honest, I suspect you'll get by with it. At worst, you might have trouble getting medium presses when your battery is at 2.9V.

There is the potential corruption issue. Mike C says with the chips running extended times at low voltage he can verify EEPROM corruption. For awhile this bothered me, and I've seen some comments of lights misbehaving that do smell like corruption, but I can't actually see how eeprom corruption breaks the light. That's just configuration values, things like is memory enabled or not. The main menu should operate regardless of what the eeprom state is, and you should be able to get to reset, but I'm not 100% sure that some corner case can't break something. And is it possible to corrupt program memory? Again, I'm not sure. I have seen the non-V chips just occasionally do strange things when in very low voltage, with improper BOD setting, like lock up in a high current state, and so you may just get that the clicks occasionally don't work.

The specs documented are safe, but I'm sure over time people will figure out what they can get by with.

By the way, there's presently a known bug where turbo tap up doesn't work in the biscotti-HD build. Will be fixed in next version. Those features will move out of the untested category.