[WIP] 17mm DD+single-7135 driver / single sided / Dual-PWM

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Pablo E.
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Hi Tom, your explanation is highly appreciated.
I also thought about removing mask, but i preffer contact them; i don’t want end up with ruined boards and without the possibility of asking for new ones.

tech
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Is v009 the latest and best version to order for a FET+7135 driver?

wight’s profile says he has been absent for a while so there were no updates in the OP.

thanks.

Tom E
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Pablo - The masking is easy to scrape off - I use an exacto type knife with a curved edge - works great, never had a problem - the curved edge is the important part, no point to deep scratch. Actually I do this all the time when I want to expose copper for grounds, or for other traces, etc.

tech  - Well, I'm still using these v009's. Richard has an OSHPark design too, as well as other variations out there, maybe by PD68 and pyroson1.

This wight v009 was the board design the BLF A6 is based on.

Pablo E.
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Mmmm… i think i have a perfect knive for that somewhere, I might give it a try.

tech
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Thank you, Tom E.

guess I’ll order the v009’s

Sirius9
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I think you can use really fine sandpaper, just lay it on a flat surface and you can sand off mask coating! At least I could try that method…

 

Pablo E.
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Yes, sanding is an option, but i have experienced lapping tiny things very difficult to do even, being borders worn much faster than center.

BTW, i already have a new boards bach on a new panel, nice good service from OSH park :bigsmile:

Neilyboy
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This is my first time building the a driver on my own. I have everything needed my question is do I flash the attiny before or after I bake it on the pcb? I assume I can flash and re-flash in circuit.
Thanks,
Neil

Tom E
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Neil - You can do it before or after, I've done them both ways.

Before: the SOIC-8 clip does seem to work fine with the "in air" MCU. Just be sure you get it positioned correctly before releasing pressure on the clip - clamping down on the MCU pins. I'm always concerned I'm gonna bend pins, but it never happened, but again, I'm extra careful before I let the clip clamp down on the pins in-air.

After: as long as you positioned the parts correctly, on this board you should be able to get a good clip on the MCU. Be sure your clip is wired correctly with a good ground. (lot of earlier posts and ref. pics and posts had it wrong!!). Also, I found it helps cleaning up the MCU pins with isopropyl alcohol to get off any residual flux from the reflow. I like using a small stiff brush.

Note: I updated the flashlight wiki page on the AVR Drivers for the ground pin connection here: http://flashlightwiki.com/AVR_Drivers. The ground is on dongle side pin #10 (or #8), not pin #4.

tech
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I was told to use a horse hair brush to clean pcbs; so I went to a nearby horse stable (fairly common here) and got some hair for free. bundled them into a brush and it works great.

Tom E
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Interesting bout the horse hair... How could you make a brush though?

For the grnd wire, it worked for me a long time not having it wired correctly, but had occasional problems, thinking it was the clip, etc. - intermittent issues. Once I corrected the grnd wire, worked sooo much better. Only problems I've had since is when there's flux on the pins, if I didn't clean them first. After cleaning, works all the time. Been trying to make a habit of always cleaning, since I'm probably getting flux contamination on the clip , and could build up. The clip can always be cleaned as well.

Neilyboy
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Tom E wrote:

Neil – You can do it before or after, I’ve done them both ways.

Before: the SOIC-8 clip does seem to work fine with the “in air” MCU. Just be sure you get it positioned correctly before releasing pressure on the clip – clamping down on the MCU pins. I’m always concerned I’m gonna bend pins, but it never happened, but again, I’m extra careful before I let the clip clamp down on the pins in-air.

After: as long as you positioned the parts correctly, on this board you should be able to get a good clip on the MCU. Be sure your clip is wired correctly with a good ground. (lot of earlier posts and ref. pics and posts had it wrong!!). Also, I found it helps cleaning up the MCU pins with isopropyl alcohol to get off any residual flux from the reflow. I like using a small stiff brush.

Note: I updated the flashlight wiki page on the AVR Drivers for the ground pin connection here: http://flashlightwiki.com/AVR_Drivers. The ground is on dongle side pin #10 (or #8), not pin #4.

Thank you so much for the detailed info.
Neil

tech
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horsehair is supposed to be an anti-static material (not easily charged electrically).

I stole my girlfriends’ old makeup brush and replaced / glued the horsehair in. Hope she is ok with that.

hank
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Quote:
How could you make a brush

Shrinkwrap-and-glue a bundle of horsehair over the end of a stick. Google ‘handmade brush’ or ‘homemade brush’ for pictures.

Trim the end with a razor for applying paint, or leave the end variable for ‘dusting’

giorgoskok
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I think this is the right thread to ask.
Are there any firmwares except toykeeper’s ready-to-flash ?
Could you provide me a link ?

Tom E
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giorgoskok wrote:
I think this is the right thread to ask. Are there any firmwares except toykeeper's ready-to-flash ? Could you provide me a link ?

Not sure. I don't usually post HEX files because I build mine on demand for modes, tweaked, turbo timeout setup, etc., so not a good idea, unless you have a fixed, static setup: same hardware, same modes, same options.

This is why I'm going with the more versatile programmable UI, so we can use a common hex file, then reconfigure it after it's burned in, but this requires more memory than a 13A has, so why we are migrating to the Tiny25 and Tiny85.

giorgoskok
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Tom E wrote:

giorgoskok wrote:
I think this is the right thread to ask. Are there any firmwares except toykeeper’s ready-to-flash ? Could you provide me a link ?

Not sure. I don’t usually post HEX files because I build mine on demand for modes, tweaked, turbo timeout setup, etc., so not a good idea, unless you have a fixed, static setup: same hardware, same modes, same options.

This is why I’m going with the more versatile programmable UI, so we can use a common hex file, then reconfigure it after it’s burned in, but this requires more memory than a 13A has, so why we are migrating to the Tiny25 and Tiny85.

Thanks for your answer. I’m new to the whole programming thing , and I don’t know how to do edit modes on code and so on.
I’m still searching , but if you had any recommendations (where to start from , or some guides) it would be great.

Thanks again

Tom E
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CRX's incredible reference thread, http://budgetlightforum.com/node/26665, has a section for programming drivers - you will find some useful info there.

I'm using the latest Atmel Studio 7, free download here: http://www.atmel.com/tools/atmelstudio.aspx. You can begin with that and go from there, if you haven't dnld'ed it already.

wight
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Looks like plenty of interesting discussion happened on this one while I was out. I think that I’ve skimmed it all, but I didn’t necessarily absorb everything and I know that some of this stuff gets discussed in other threads too.

  • I’m not sure what’s up with all of the OSH Park mistakes. I’ve certainly made some flagrant mistakes on other things with them in the past, but as far as I know everything is pretty kosher with this one. I definitely do go right up to the minimum tolerances sometimes, but I do not see how that would cause such flagrant issues with the resist mask…
  • I’m inclined to agree with anyone who thinks that more of the GND ring should be exposed. Maybe I picked up the skinny-GND-ring habit form Mattaus, who knows. I do prefer to create a “dam” of resist around any component pads that are near the edge of the board. That helps prevent components from scooting towards the edge of the board when soldered, which can create fitment/shorting issues once installed in a light. I don’t always achieve this of course, it’s just my preference. In any case, Eagle doesn’t really have an automatic way to do make sure those dams happen – so the easiest solution is a skinny GND ring. I think I have an updated version of this board with a larger GND ring. I’ll see about dragging that out.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

Tom E
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Hi Alex!! Wow - welcome back!

 I was getting a flash going from hi/turbo to moon (on this FET+1 w/ATTiny85, SIR800DP FET) that I was able to solve in firmware (e-switch firmware called "Narsil"). Had to do with removing redundant setting of PWM modes.

For a power switch setup (also on this FET+1 driver, ATTiny25 w/SIR800DP), I tried several things in firmware with no luck, then added a 12K resistor across the FET (gate resistor) and it solved it perfectly.

One guy, think an EE, found a FET that didn't have the flash. I did some amps tests and the 12K resistor seemed to have no effect - I'm pretty happy with the fix.

25, 45, and 85's seem to have their own problems in high amp setups. Caps seem to fix it - I add a 0.1 uF cap across the MCU grnd and VCC pins and it fixed it with the e-switch firmware/setup. On power switch setups, I stacked a 2nd 10 uF cap on the C1 cap and it fixed it. The problem is in either just hi/turbo or any FET modes, the MCU flakes out - resets sometimes, or get weird blinks, etc.

I agree with more exposure of the ground ring - would help, I've done lots of scraping.

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Thanks Tom E.

  • So that’s a 12k pulldown resistor on the gate? (EG the resistor is connected to the “gate” pin and to “GND”?)
  • How are people feeling about 0603 sized components these days? Sourcing is not an issue: the days of using Nanjg boards for donor components are well past. Almost everyone building a driver of this type is certainly sourcing parts elsewhere. It’s just a question of whether people can handle soldering the smaller size stuff.
  • I’d say that the v009 layout of this board (and probably all of the previous ones) does not provide very good filtering for the MCU. We got away with it before, but it looks like the seams are coming out now. A decent sized overhaul is in order to fix that… and frankly I think it’s probably time to start breaking these boards out into single cell and multi-cell rather than “universal”. In the past I liked to keep these designs as flexible as possible, but the more we push the limits the more specific they need to be if all else remains the same. The 17mm boards cost <$0.75/ea from OSH Park, so it’s hard for me to feel bad about making them less universal. In order to meet these new design goals it seems like something’s got to give – either step down to smaller components, build less universal board layouts, move to some pricier parts, or all of the above…
  • Speaking of pricier parts, back to the LDO discussion. From my looking at the ATtiny85 datasheet in Section 21.3 / page 163… looks like 8Mhz @ 2.5v has Atmel’s blessing. So maybe a 2.5v LDO if we wanted to use an LDO in single-cell applications? I’m not 100% confident that we even want to do that. (For the higher voltage stuff I’m pretty confident!)

EDIT: added strikethrough for “DOPE!” moment. See posts below for correction(s).

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

FmC
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 I don't see 0603 being a problem, as most people would be using paste/heat gun rather than manually soldering these things with an iron. If the size saved is going to make a board possible where it was otherwise not, then I say go for it.

 The additional/larger Cap seems to overcome the MCU spike issue on the current boards, so another revision of this design may not be time well invested. I think a new design targeting multi-cell applications(Buck w/ATtiny) would now be more sought after.

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I manually solder by hand and have no issue using 0603 parts if it gets me the driver I’m after

Pastebin                                      &nbs

Tom E
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wight wrote:
Thanks Tom E. * So that's a 12k pulldown resistor on the gate? (EG the resistor is connected to the "gate" pin and to "GND"?) * How are people feeling about 0603 sized components these days?

Yes - 12K pulldown - it's what I had available and seems to work well. 0603 sizes are fine with me. I certainly would like Richard to chime in on this, but not sure if he's been spending much time on the 25/45/85's.

I haven't built any LDO based boards yet but am certainly interested because I have a couple of lights I'd like to use them in (e-switch multi-cell for 6V LED's).

wight
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I’ll get back to those comments, I’m just posting right now to point out that using a 2.5v LDO is a bad idea. (In other words I’m correcting myself.) I don’t think an LDO can be practical for single-cell since it won’t fully open the gate with most of the FETs we use. (The MCU will also drop some voltage, so there just won’t be enough to make the FET happy.)

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

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Wight, I was about to comment on the low LDO voltage, and I agree with your correction.  You really want a 4V+, preferably 5V LDO for two reasons:  First, you want the gate voltage to be as high as possible to minimize RDS, and second you want to dissipate least amount of heat possible in the LDO, especially the smaller package ones if you are running 3S or 4S.

If you use an LDO with any clicky application you generally need to add a pulldown resistor to drain the capacitors so that you can switch modes fast enough with off-time memory.  

As far as use of an LDO with 1S goes, I have found that most of the true LDO regulators will work with 1S and that the voltage drop across them isn't much worse than a normal schottky diode, but you do have to contend with the extra capacitor and the timing issue (see paragraph above). 

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I really think the FET makes a difference. I’ve used PSMN3R0-30YLD on wight’s FET+1, with t25 and bistro for a single XM-L2 without issues and used it on PD’s DoubleDown with t25 and bistro for a triple XP-L HI, no issues with just the standard components, both are power switch lights.

wight
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FmC wrote:

 I don’t see 0603 being a problem, as most people would be using paste/heat gun rather than manually soldering these things with an iron. If the size saved is going to make a board possible where it was otherwise not, then I say go for it.

 The additional/larger Cap seems to overcome the MCU spike issue on the current boards, so another revision of this design may not be time well invested. I think a new design targeting multi-cell applications(Buck w/ATtiny) would now be more sought after.

If people have to manually stack a second cap, that’s pretty crap for reflow IMO. Same thing with the 0.1uf that Tom E has been adding to fix ATtiny25 problems. I’ve publicly done several major reworks on the FET driver layouts + several more that never saw the light of day, so one more to get a better build process might be worth it.

As far as multi-cell applications: For me the first step is probably a board similar to these (DD+7135) with the addition of an LDO. That’s a much smaller leap than the leap to a buck driver – remember that I’ve never designed a successful buck driver. I tried pretty hard to design/build a QX5241 based on early on but couldn’t get it functioning. I learned a lot from that process and applied some of it when I did a much more handsome MAX16820 based board… which I never ended up building / testing. Since then RMM has gotten several sizes of buck driver working and all of us have learned a little here and there. I’m confident that I can design a buck driver which works now, especially with a few well placed tips from RMM. I just don’t plan to hop on that task first thing.

pyro1son wrote:
I manually solder by hand and have no issue using 0603 parts if it gets me the driver I’m after
Sounds like the consensus is that we’ll take our lumps on 0603 where necessary. If I build something ‘unkind’ you have only yourselves to blame. Evil Wink
Tom E wrote:

Yes – 12K pulldown – it’s what I had available and seems to work well. 0603 sizes are fine with me. I certainly would like Richard to chime in on this, but not sure if he’s been spending much time on the 25/45/85’s.

I haven’t built any LDO based boards yet but am certainly interested because I have a couple of lights I’d like to use them in (e-switch multi-cell for 6V LED’s).

Thanks Tom E, that’s what I wanted to know. I’ve got some thoughts on reducing the quiescent draw of momentary lights a little bit more, we’ll see where they go.

RMM wrote:

Wight, I was about to comment on the low LDO voltage, and I agree with your correction.  You really want a 4V+, preferably 5V LDO for two reasons:  First, you want the gate voltage to be as high as possible to minimize RDS, and second you want to dissipate least amount of heat possible in the LDO, especially the smaller package ones if you are running 3S or 4S. / If you use an LDO with any clicky application you generally need to add a pulldown resistor to drain the capacitors so that you can switch modes fast enough with off-time memory. / As far as use of an LDO with 1S goes, I have found that most of the true LDO regulators will work with 1S and that the voltage drop across them isn’t much worse than a normal schottky diode, but you do have to contend with the extra capacitor and the timing issue (see paragraph above). 

Good points RMM.

Getting back in the saddle really has me dredging my mind for some stuff. I go back and forth forgetting important things – for example I’ve just been reminded that we normally depend on an internal 1.1v vRef for LVP with the ATtiny13a. There are tons of other equally important things that are slowly filtering back into my consciousness.

chouster wrote:
I really think the FET makes a difference. I’ve used PSMN3R0-30YLD on wight’s FET+1, with t25 and bistro for a single XM-L2 without issues and used it on PD’s DoubleDown with t25 and bistro for a triple XP-L HI, no issues with just the standard components, both are power switch lights.
Is that what I’ve recommended / used in the past? Maybe I should do a build with the SiR800DP. I think I bought 1 or 2, but I don’t know that I’ve ever built anything with them. As I recall the SiR800DP is a bit different from many of the other FETs we run into.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

chouster
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Yes that’s the one you kinda recommended in your A17DD-SO8 / A20DD-SO8 / etc – thread. Seems like there has been a lot of discussion about the best performing FETs to use. Still haven’t read and more importanly understood all the info about FETs that was posted all over the forum. By the way, thanks, wight, for letting me see comfy’s scope images for the first time. Smile I’ve been clicking through that thread once or twice and wondered what the lacking images would look like. Most of this stuff is over my head but it’s quite entertaining.

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The SiR800DP is a beast---it can handle more current than most of the other FETs I've tried---the difference is much more than the datasheet would suggest.  If you try and run 4x XHP70 from a single PSMN3R0 you will find that it quickly desolders itself; with a single SiR800DP it is fine without making any other changes--and that's with a 5V gate drive (much higher than we usually get with 1S setups).  So yeah, you can run crazy stuff through an SiR800DP.  It seems to even run cooler than the 0R9 NXP FET I have in the same situation.  

The SiR800DP does suffer from dV/dt induced turn on when you're switching from 100% quickly to moonlight (that's the little light blip you see).  As Tom E. noted, a small pulldown resistor solves that issue.  

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