<whitequark>
wpwrak: not power at all. and they look a bit too thin, anyway
<whitequark>
and when I place the photonegative above the board, there is no visible gap between the image and the actual wires on board
<whitequark>
I'll post a photo tomorrow, I think
<whitequark>
(maybe my design is crappy, and someone will tell me that. that would be very good, actually)
<wpwrak>
whitequark: (no gap) does that mean that the traces are the same width as the design or that they're no wider than the design ?
<whitequark>
wpwrak: they're the same width, through they do not look so (probably due to an optical illusion. white on black looks wider than copper on PCB)
<whitequark>
the .016 trace looks a bit too narrow near 0805 components, through I usually lay out digital lines with .012
<wpwrak>
whitequark: (15 components) that's simple than atusb, 150% of the complexity of atben. both are 8 mil designs. atben has trace failure ratio of about 25%, or less. did you check for problems before etching ?
<wpwrak>
(illusions) yeah, you can never tell ;-)
<whitequark>
8 mil!!!
<whitequark>
now I feel myself like an idiot.
<wpwrak>
welcome to the wonderful world of toner transfer ;-)
<whitequark>
do we both use same mils?
<wpwrak>
truth be told, i don't think my traces are really 8 mil. most likely, they're ~10 mil. otherwise, i wouldn't have so many shorts in zones with (nominally) 8 mil clearance.
<whitequark>
hmm.
<whitequark>
I didn't really tried 8mil traces at all
<wpwrak>
of course, shorts are easy to remove. all they take is one swift cut :)
<wpwrak>
you're using a photochemical process, right ?
<whitequark>
yeah
<whitequark>
dry film photoresist
<whitequark>
it works WAY better than toner transfer (for me)
<wpwrak>
that should give you even better accuracy than toner transfer, yes
<whitequark>
at least it is repetitive, i.e. I get exactly the same crap each time
<whitequark>
and the failure rate is maybe 10 or 50 times less than with toner transfer. I was not able to do a single board without errors with the latter
<wpwrak>
for toner transfer, all the magic is in the paper. plus, you have to be either very steady at ironing, or automate the proces
<wpwrak>
(errors) easily fixed errors or real problems ?
<whitequark>
for the toner transfer, they often were serious
<whitequark>
for the photoresist, they are often fixed by a cut or a small piece of thin wire
<whitequark>
I use laminator to attach the photoresistive film to the board, anyway
<wpwrak>
thin wire is level 3 ;-) a scratch / a bit of acid resist pen before etching would be level 1. a cut or a solder bridge after etching would be level 2
<whitequark>
ah yes, acid resist pen. cd marker works somehow for that
<wpwrak>
i almost always have level 1 problems. some of them may not be very serious, though.
<whitequark>
I think that my worst problem is with etching itself
<wpwrak>
what acid ?
<whitequark>
I use FeCl3 for that
<wpwrak>
should be "friendly", although a mess
<wpwrak>
do you reuse it a lot ?
<whitequark>
yes
<wpwrak>
that may be the problem
<whitequark>
I think no. if you leave it exposed to air, it eventually oxidizes all the copper
<whitequark>
and, furtherly, FeCl2 converts itself to FeCl3
<wpwrak>
erm, how long to you leave your boards in the acid ?
<whitequark>
I check them regularily, and remove when all copper not covered by the resist is etched
<whitequark>
~20-30mins at room temp.
<wpwrak>
okay. 30 min is still okay.
<whitequark>
(oxidizing trick) for that to work, you need to add 35% HCl to it sometimes
<wpwrak>
you're moving the board around while etching ?
<whitequark>
yes, several times
<wpwrak>
like, all the time ? :)
<whitequark>
otherwise it'll stall at some point
<whitequark>
no, 2 or 3 times maybe
<wpwrak>
oh no, it won't stall. it will just surprise you ;-)
<whitequark>
hmmm
<whitequark>
what kind of surprise?
<wpwrak>
uneven etching. stops in some areas (because it's blocked by byproducts) yet happily etches on in others.
<wpwrak>
it's basically the same as with an excessively aggressive acid. also there, you can't control the distribution.
<whitequark>
well, my problem, as I understand it, is: it should etch the unneeded copper from top to bottom, and it should not etch the traces from sides. but it still does
<wpwrak>
you have to move it around a bit more
<whitequark>
sounds reasonably, I'll try that with next board
<whitequark>
thanks
<wpwrak>
also, FeCl3 is supposed to be warmed up. it's a mess, though.
<whitequark>
grhm, warming it up isn't easy at all
<wpwrak>
if you have acceptable ventilation, i would recommend giving HCl+H2O2 a try. that acid doesn't last very long (hours, not days), but it's so incredibly cheap that you usually don't care.
<whitequark>
I should either get some equipment, or convince my parents that the spots of FeCl3 all over the kitchen is an acceptable byproduct of etching...
<wpwrak>
it works at room temperature and is transparent. its downside is that the Cl evaporates. so if you leave it inside, it will attack its surroundings.
<wpwrak>
FeCl3 is a pig ;-)
<whitequark>
when it is cold, I manage to not leave traces anywhere
<whitequark>
(HCl+H2O2) there is a terribly small problem. you can't freely buy acids (and more than ~3% H2O2) in russia
<wpwrak>
cold FeCl3 is also the one that doesn't work very well ;-)
<whitequark>
they're regulated by some idiotic act written to prevent illegal drug manufacturing or something like that
<whitequark>
HCl, H2SO4, H2O2, benzene, phenol, even KMnO4
<wpwrak>
one nice thing about HCl+H2O2 is that, if you let it evaporate, it produces nice crystals. you can sweep them up and throw them away with solid waste. (that may not be entirely according to the rules, but there shouldn't really be any danger in this)
<wpwrak>
HCl ? that's used all over the place.
<wpwrak>
H2O2 is used to desinfect wounds.
<wpwrak>
(at low concentrations. at higher concentrations, it's more like causing them ...)
<whitequark>
(H2O2) yeah, low concentrated one can be bought freely
<whitequark>
but anything more ~10% is not available
<wpwrak>
10% should be plenty ;-)
<whitequark>
HCl too
<wpwrak>
for etching PCBs, the usual concentration is 5%. it does mean that you can't easily reoxidize your acid, though. but hey, it's cheap. just mix some new.
<wpwrak>
MCl .. hmm, maybe you have to look at places for professional/industrial supplies. in general, even ~35% should be in very common use.
<whitequark>
well, the singke place where I've found some HCl was my university. technically, teachers aren't allowed to give students more than needed for labs, but they can sometimes look the other way (especially if you ask him)...
<whitequark>
*single
<wpwrak>
the HCl only gets really nasty if you give it a lot of oxygen. so mix 30+% HCl and 30+% peroxide, toss some copper into it, and watch the fun ;-) (preferably from a safe distance)
<whitequark>
industrial suppliers require a company to work with, not an invividual
<whitequark>
same with professional ones AFAIK
<wpwrak>
maybe HCl is know under some other name. in english and spanish, it's "muriatic" acid. it's a very old chemical, so it may have many "strange" names.
<wpwrak>
don't you have hardware stores in russia ?
<wpwrak>
(construction/plumbing/etc. supplies)
<whitequark>
(about name) well, maybe I'm not a chemistry genius, but I cannot know it THAT bad :/
<wpwrak>
HCl is also used for swimming pools. of course, that may be something that's not so popular in russia :)
<wpwrak>
(name) you may be surprised ;-) maybe ask someone who works in the field.
<whitequark>
(pools) I think they use not the HCl itself, but Cl2 gas. it decomposes to HCl+HOCl in water, with the latter giving all the effect
<whitequark>
(name) I sure I know how it is called, really. that's so basic knowledge
<whitequark>
(stores) hmm, I never thought (and never heard) that I may find HCl there. may be a place to check
<whitequark>
wpwrak: hmm... maybe it's not controlled here? at least I never heard of that
<wpwrak>
whitequark: (uncontrolled pH level) well, have fun with your pool then ;-))
<wpwrak>
"Metal fittings, pump impeller, heater core may corrode", "Plaster walls are etched", "Eye irritation may occur", ...
<whitequark>
uh-oh
<wpwrak>
and there's also the very subtle "Chlorine activity is slowed and inefficient". in other words, the chemicals won't get you, but the bugs will ;-)
<whitequark>
well, a quick googling (in russian) reveals a lot of pool tools sellers, so probably I'm wrong
<whitequark>
didn't knew that managing a pool is so hard, hm
<wpwrak>
seems to be pretty sophisticated, yes. i wonder how many pool owners know all this ;-)
<wpwrak>
but yes, pool supplies shops may be a good place to ask for HCl. they may sell it by the barrel :)
<whitequark>
I don't know anyone with a personal pool anyway
<whitequark>
heh
<whitequark>
the construction market is another good place
<wpwrak>
other places would be shops with plumbing supplies. i'm not quite sure that the plumbers use it for, but at the local hardware supermarket, they keep HCl in bottles of 5 l (or maybe more) in the plumbing section.
<wpwrak>
yeah
<wpwrak>
it's also used for cleaning, concrete and other things
<wpwrak>
just don't use it on those dainty marble surfaces :)
<whitequark>
ahh, carbonates...
<wpwrak>
yes, could be for lime/scale removal
<wpwrak>
whitequark: anyway, for HCl+H2O2, you want to use some sort of balcony. not necessarily for the etching itself, but for placing the acid after use, to let it quietly evaporate
<whitequark>
I think that warming FeCl3 is less difficult, currently
<whitequark>
but I'll record your method, thanks
<whitequark>
btw, it's 5:30AM here and I'll go to bed :)
<wpwrak>
warming FeCl3 also has its traps ;-)
<wpwrak>
a good time for some rest. just before the evil day star rises ;-)
<whitequark>
yeah. night is the best time for work
<wpwrak>
whitequark: (traps) risk of the outer container breaking due to heat stress. risk of overheating. limited choice of locations (e.g., the kitchen oven may be less convenient and less spill-tolerant than, say, the balcony)
<whitequark>
wpwrak: it's quite cold at the balcony now (not to say it is... eh... cluttered up)
<whitequark>
and no wall sockets there, so I'd leave the door open etc.
<whitequark>
hm.
<wpwrak>
whitequark: yeah, an open door will do, too. just have some air flow. the issue is more finding a place where a) nobody will bump into your setup, and b) where spill can be tolerated. of course, you can use temporal separation instead of or complementing spacial separation :)
<wpwrak>
kristianpaul: those pictures make a lot more sense once you realize they're from the UK ;-)
<whitequark>
wpwrak: what about ammonia (or ammonium?) persulphate?
<whitequark>
it is cheap, easily obtained and does not have color
<wpwrak>
whitequark: i tried it once, briefly, and got uneven etching. but yes, it could be an option.
<wpwrak>
wonders what happened with the panelized gerbers. it's been a while since that order went out ...
<kyak>
wpwrak: can two atben's communicate between each other? or two atusb's?
<wpwrak>
kyak: sure
<kyak>
so they are absolutely the same, basically it's just the form factor that is differenet?
<wpwrak>
kyak: atusb = atben+usb_to_spi (more or less)
<kyak>
ah, ok
<kyak>
i wonder if they are going to be sold in pairs
<kyak>
i.e. atben+atusb
<wpwrak>
kyak: thet're not absolutely identical: atben doesn't use the transceiver's clock output while atusb used it to clock the cpu. furthermore, atben doesn't have a reset input (so you have to power-cycle it) while atusb does.
<wpwrak>
kyak: dunno what tuxbrain has decided on
<kyak>
wpwrak: so the atben cpu is running on internal clock?
<wpwrak>
kyak: the atben transceiver has its own crystal, yes. there's no "CPU" on atben, just the RF chip
<kyak>
but these are two same RF chips on atben/atusb?
<wpwrak>
atben and atusb use the same RF chip. atusb also has an ATmega32U2 to interface the transceiver (SPI) with USB
<wpwrak>
"transceiver" = "RF chip"
<kyak>
did you decide not to use the external clock for atben to save space?
<wpwrak>
kyak: i tried to use the ben's system clock to clock the transceiver, which would have eliminated the crystal. unfortunately, the ben's clock is too noisy for this.
<kyak>
just trying to understand, it seems that atben is "worse" than atusb?
<wpwrak>
kyak: atusb saves one crystal (the avr would typically also have one) by re-using the transceiver clock.
<wpwrak>
kyak: atben is simpler and cheaper than atusb.
<kyak>
do you have any idea what the price could be for both of them?
<wpwrak>
kyak: tuxbrain once mentioned an estimate of EUR 25 for atben and EUR 35 for atusb, but i don't know if these are still current.
<kyak>
wpwrak: is there going to be a casing for them?
<wpwrak>
kyak: that's still under investigation :)
<wpwrak>
kyak: one idea is to ship them with a bit of silicone, so can you make your own casing.
<kyak>
wpwrak: seems there are no LEDs, too? My eye is not trained, i couldn't see it even on magnified picture
<wpwrak>
kyak: but there are still a few unknown parameters, such as whether the material is easy enough to handle, what quantity is needed, and how it affects RF performance. wouldn't be so good if it absorbed or reflected 90% of the signal ;-)
<wpwrak>
kyak: atusb has one LED
<kyak>
wpwrak: silicone hasn't done any harm to anyone, ever ;)
<kyak>
wpwrak: i think it should be posible to attached one atben to my linksys router (maybe i'll have to revert the SDIO card mod) and turn my linksys router into a WPAN-capable device :)
<kyak>
that would be cool
<wpwrak>
sounds like a fun project :)
<wpwrak>
note that atben requires the ability to cycle the voltage supply (for reset)
<wpwrak>
well, in theory, you don't need that, but it's safer if you have that ability
<kyak>
i can cycle the router itself, or come up with an idea how to detach atben from the router
<kyak>
wpwrak: do you think there could be some problems with 2.4 kernel?
<wpwrak>
kyak: well yes, 2.4 doesn't have any in-kernel support for IEEE 802.15.4
<kyak>
luckily, i should be able to use 2.6 with wrt54gl..
<wpwrak>
good :)
<whitequark>
kyak: do you have wrt54gl? :)
<kyak>
whitequark: yeah :)
<whitequark>
kyak: one of worst routers I've seen. slow CPU, 100M switch and costs too much
<kyak>
whitequark: it's a router, what kind of CPU do you expect? :) It' sdoing it's job fine, and i don't even have 1Gb network card to complain about 100 Mb switch
<kyak>
costs too much? i doubt it is still sold
<kyak>
moreover, it was a present and back in those days (around 5 years ago) it was maybe the first home router running Linux
<kyak>
wpwrak: could you correct me if i'm wrong: i need to find at least 4 GPIOs to be able to communicate with atben. The 4 GPIOs are already used for SDIO mode, and i would need to find other spare GPIOs (there is no option to share GPIOs?)
<wpwrak>
kyak: you need at least one more, for the interrupt (that is, unless you want to poll)
<wpwrak>
kyak: there's also another signal that can be useful to have (to enter sleep mode and to precisely trigger a transmission). but it's less important than the others.
<kyak>
all right, so it counts to 5-6 GPIOs.. I'll check if wrt54gl has those
<whitequark>
kyak: you'll probably need to cut traces to leds then. I doubt they can work simultaneously with atben
<whitequark>
kyak: oh yes, 5 years ago it was a very good router. it is still sold, yeah, but it is nothing compared to e.g. last tplink model. 1gbit, fast cpu and usb for the same cost
<kyak>
whitequark: hmm, having a look at GPIO7, which they took from LED, seems that it was not necessary to cut the traces?
<kyak>
whitequark: sure, it's not a modern router :)
<kyak>
i wish i had USB, too
<whitequark>
kyak: 3k RUR for gigabit wireless-n router with excellent linux support isn't a lot at all :)
<kyak>
whitequark: let me finish beating the crap out of my old good linksys before you persuade me to go and buy a new router :)
<whitequark>
kyak: if you'd follow my advice, at the time you'll brick and/or fry your old router you'd already have a replacement ;)
<kyak>
tries to extrapolate whitequark's advice to womenfolks
<whitequark>
kyak: in the cpu world, that's called pipelining. I like to apply this technology to various human activites
<whitequark>
consider, for example, eating icecream. by the time the first one has melted completely, you'd eat a half of second and buy third
<wpwrak>
whitequark: and if you had concentrated on just the first one, you'd have eaten it before it melted in your fingers ;-)
<kyak>
plus you would spend three times less money :)
<kyak>
damn is it hard to find schematics for that router..
<whitequark>
wpwrak: yeah, that's the essence of pipelining
<whitequark>
kyak: openwrt folks have good docs for it
<wpwrak>
kristianpaul: the last one looks weird until you realize that it's from the UK where they drive on the wrong side of the street (it's fun to ride in someone's car in front there. at each intersection, you think they're about to commit suicide :)
<kristianpaul>
wpwrak: ah, yes :-)
<whitequark>
kyak: the sd card is bitbanged too
<kyak>
whitequark: right, so?..
<whitequark>
kyak: well, it's not SDIO then. just plain SPI
<kyak>
shrugs
<wpwrak>
whitequark: could be any of the three modes :) 4-bit SDIO, 1-bit SDIO, SPI.
<larsc>
is there 1-bit SDIO?
<larsc>
apparently there is
<kristianpaul>
sure
<wpwrak>
larsc: i actually didn't check ... but there's certainly 1-bit SD
<kristianpaul>
SIE have 1-bit SDIO i remenber
<larsc>
although it uses an additional pin for IRQs
<wpwrak>
ah, "1 bit" is the bus width. still has a lot of signals.
<kristianpaul>
(lot of signals) thats the fun part ;-)
<whitequark>
wpwrak: is there any code for proprietary sd protocol in linux core for bitbanging?
<qi-bot>
[commit] Werner Almesberger: tools/lib/: atnet now works (tried atrf-txrx send and receive, atrf-rssi) http://qi-hw.com/p/ben-wpan/4246535
<whitequark>
I think no
<whitequark>
anyway, it would not be useful at all, as the SDIO has one main advantage over SPI, speed, and that's low anyway with bitbanging
<larsc>
sdio won't work with bitbanging
<larsc>
at least not with the current linux drivers
<larsc>
mmc bitbanging is done in mmc spi mode
<wpwrak>
whitequark: i don't see any bit-banging driver. it wouldn't be useless, because you still have the wider bus (in case of 4-bit SD(IO))
<wpwrak>
larsc: why wouldn't it work ?
<whitequark>
wpwrak: and, given the gpio framework, you'd call slow bitbanging functions a lot more. that's a C function call per bit
<larsc>
wpwrak: because there is no support
<wpwrak>
whitequark: i didn't say it would be blindingly fast ;-)
<wpwrak>
larsc: okay, but one could write a driver :)
<larsc>
maybe
<whitequark>
wpwrak: then, what are advantages of wider bus? more gpio pins doing useless work?
<wpwrak>
the good thing about linux is that "that's not possible" hardly exists, it's usually "nobody has gotten around to doing it yet" ;-)
<wpwrak>
whitequark: they would make it a bit faster than just spi
<whitequark>
wpwrak: (linux) more "only you in the whole universe need that, and every other man who tried to do thatis dead"
<wpwrak>
whitequark: spi: 2.5 toggles per bit. 4-bit sdio: 4 toggles per 4 bits
<wpwrak>
(on average)
<whitequark>
wpwrak: 2.5 toggles?
<whitequark>
sdio does have clock, too
<wpwrak>
whitequark: set data if it changed = 0.5, raise clock = 1, drop clock = 1
<whitequark>
and a read, too
<whitequark>
it has the same cost as write
<wpwrak>
for tx ?
<whitequark>
ah yes.
<wpwrak>
read may actually be even more expensive
<whitequark>
on controllers where gpio bitbanging is worth implenting, it is a cpu-accessible register read (or write for toggles)
<larsc>
and you need to change direction
<wpwrak>
btw, on the ben, i can poll a gpio at about 10 MHz. (that was a loop that counts cycles until a pin changes)
<larsc>
wpwrak: with gpio_get_value() or direct register access?
<wpwrak>
larsc: if you alternate tx and rx, which fortunately doesn't happen so much in block transfers :)
<whitequark>
wpwrak: that's 33 cycles per poll, right?
<wpwrak>
larsc: direct access
<wpwrak>
whitequark: in that order, yes. maybe the rate was actually a bit higher, could have been 12 MHz. (i didn't measure the true pulse length)
<larsc>
reading from the register alone should probably kill a few cycles
<whitequark>
wpwrak: what was your statement? while(SOMEGPIOREG & (1 << bit)) i++; ?
<wpwrak>
whitequark: (on controllers where gpio bitbanging is worth implenting) do yo uhave cpus where the gpio registers are inaccessible ? ;-)
<whitequark>
wpwrak: sometimes i2c expanders are used, when there are not a lot of gpios on cpu itself
<whitequark>
wpwrak: this is especially the case on PDAs
<wpwrak>
do i--; while (!(*pdpin & 0x1000));
<wpwrak>
whitequark: okay, via i2c, it would be indeed evil ;-) bitbang i2c, then bitbang the gpios on i2c ;-)
<whitequark>
wpwrak: that translates to ~15 mips instructions
<larsc>
wpwrak: the --i goes into the branch delay slot
<wpwrak>
larsc: yup ;-)
<whitequark>
the return with delay slot is just _weird_
<wpwrak>
larsc: is the jz4720/40 "mips32" ? from what i saw, it's not "mips2".
<larsc>
wpwrak: it is
<whitequark>
wpwrak: it's R4k-compatible, and that is AFAIK mips32
<larsc>
btw. the peripheral bus is clocked at 82 Mhz
<larsc>
iirc
<wpwrak>
remembers the day where he was proud to have an SGI with a 12 MHz R2000 on his desk ;-)
<whitequark>
larsc: it's divided by 3 in 4750, but I don't know what's in 4720
<larsc>
whitequark: iirc 4
<larsc>
but could be 3 as well
<whitequark>
larsc: also, I have had a strange feeling that registers are accessed through AHB after reading manuals, however that may be grossly wrong
<whitequark>
something in the clock generation unit made me think so, through I don't quite remember what it was
<larsc>
i think it is clocked at the same rate
<wpwrak>
yeah, no performance improvement between default architecture and mips32. i.e. the one delay slot has no cost.
<whitequark>
larsc: the AHB? yes. then, peripheral register accesses won't impose any additional delay
<larsc>
i doubt that you can access mmio access without any delay
<whitequark>
why not?
<larsc>
because that would mean they would be as fast as normal cpu registers
<whitequark>
larsc: I'd say 'as fast as normal memory
<whitequark>
and that sounds perfectly fine for me
<larsc>
my 'feelings' tell me it's not the case.
<larsc>
but i can't give you hard numbers
<whitequark>
hm
<larsc>
but Arned Bergmann told me once that mmio could easily take 100 cycles or more
<wpwrak>
i'm sure marketing would *love* an even smaller unit than a bit ;-)
<wpwrak>
maybe a "hunch", 1/100 bit ? then you'd have 3.2 Gigahunches !
<jesperj>
wpwrak: They'd love it even better if they could make it look like MB/GB/TB... "It has a stunning 2* TerraBite hdd! (* Don't read this but that equals about 20 MB)"
<jesperj>
"Bite" seems like a good candidate
<wpwrak>
ah yes, Bite would be good. or l6 TB, with l6 = 2^-22
<GNUtoo>
uhmmm
<GNUtoo>
not sure they could do import that in france, since the word is vulgar there
<GNUtoo>
if they do it would be very problematic....lol
<wpwrak>
GNUtoo: reminds me of that spanish girl who shouted encouragements ("vite ! vite !") to someone, while others looked in disbelief :)