#robotics Logs

Nov 11 2015

00:07 rue_house waaay too much
00:10 onnumberanon looks at his s
00:10 anonnumberanon step2: nrf24l01 hook up, oh god, and the only stuff available for that is arduino code...
00:11 anonnumberanon I don't think I have a choice until I get to the step where I have to rewrite all libraries for bare avr (and the one for NRF24 is quite huge if i remember correctly)
00:32 anonnumberanon I have a good challenge right now my cp2102 ISP programmer is not working. Getting 'avrdude: stk500_recv(): programmer is not responding'
06:46 anonnumberanon Well, I've created two more arduinos with the Arduino ISP method. Gonna move on to wireless between them after I sleep.
06:48 anonnumberanon I spent a long time trying to use a cp2102 usb to serial module to program the chip but it just doesn't work.
06:51 deshipu cp2102 is a serial, not isp?
06:52 deshipu you need usbasp or something similar
06:58 anonnumberanon I used Arduino Uno.
07:00 deshipu that works too
07:01 anonnumberanon I was led to believe I could make an Uno out of a bare 328 and the usb serial converter but I didnt find how.
07:01 Snert http://www.aliexpress.com/store/product/Encoder-TRD-NA1024NW-1024P-R-Koyo-encoder-TRD-NA1024NW-absolute-encoder/438730_1520375307.html
07:02 Snert this is looking damned good.
07:08 anonnumberanon what is it
07:20 Snert it puts out gray code which the arduino reads and then it knows where it is.
07:21 Snert what position the arm is in.
11:20 veverak hmm
11:20 veverak anybody any experience with openservo?
11:20 veverak seems dead to me
11:49 rue_bed 10 bit over a whole rotation
11:49 rue_bed your arms axis prolly moves 90 degrees
11:50 rue_bed so you get a full range of 256 counts
11:50 rue_bed you will get more with a pot and the adc
11:50 rue_bed Snert,
11:50 rue_bed ?
11:51 rue_bed veverak, openservo was a hit back in like 2003
11:51 rue_bed but I think it works
11:51 rue_bed someone was commercializing its works
11:53 rue_bed so your resolution would be .352 degrees
11:53 rue_bed if your arm segment is 15cm long
11:55 rue_bed you have steps 0.91mm apart
11:55 veverak well
11:55 veverak I was wondering if I could "easily" upgrade my servos :)
11:56 rue_bed if your arm is twice that overall length, its twice as much between steps
11:57 rue_bed a $1 pot rotates about 190 degrees over its reading span, which you can resolve to 10 bits on an adc
11:57 SpeedEvil resolution != accuracy
11:57 rue_bed gives a resolution of .186 degrees
11:59 rue_bed over 15cm that gives you .487mm steps
12:00 rue_bed and only costs $1 for the pot
12:01 rue_bed the tradeoffs are linearity, looooooong term durability, and time to read (the adc takes a few dozen ns to do the reading)
12:02 rue_bed just sayin :)
12:03 rue_bed I'v never heard of the pot in a hobby servo wearing out
12:03 Snert jitter on the cheap ones but I know whatya mean.
12:07 Snert I found a nice round wheel encoder printer to play grins with. Anyone seen an app that prints a linear gray or binary code in a strip somewhat like a bar code?
12:32 rue_house yup
12:32 rue_house long long ago one was written by a channel member
12:32 rue_house it made the wheel AND mask
12:45 rue_house I think I'm accidently working out how to do the analog stage of my power supply in digital time domain
13:11 rue_house at 16Mhz, an avr with a 16 bit pwm
13:11 rue_house onyl produces 244Hz
13:12 rue_house thats a really long way away from the 250khz I'm looking for
13:14 rue_house so what I need is a 16Ghz avr
13:14 rue_house with, of course, a hardware pwm system
13:14 rue_house 16 bit.
13:15 rue_house "I cant build my power supply, because todays technology is just not good enough, even something as simple as this power supply just CANNOT be done with whats available today"
13:17 deshipu physics
13:17 deshipu always getting in the way
13:17 SpeedEvil rue_house: Flip-reverse the bits of the counter before comparing them.
13:17 deshipu not to mention logic
14:32 rue_shop3 hmm whats faster 74HC or 74F
14:46 deshipu rue_shop3: depends on the height of the building you are dropping them from
14:47 ace4016 F i believe
14:48 ace4016 i believe 74AS might be the fastest?
15:01 rue_shop3 turns out, according to wikipedia, 74AS is the fastest
15:01 ace4016 >_>
15:02 rue_shop3 the door to my shop has a "nonstandard timespace" warning, a good example of this is a box of parts, if you empty the box, and fill it two strange things will happen, first, it will take much longer than expected, secondly, the parts will not all fit back in the box, nomattor how they are arranged
15:04 rue_shop3 this also helps explain other things, you can be working with a tool and put it down beside you, but when you go to pick it back up, its on the other side of the shop.
15:07 Hyratel1 I need one of those signs
15:20 rue_shop3 http://lifeboat.com/images/nonstandard.spacetime.warning.jpg
15:25 rue_shop3 ok switching out the 7414 and 7400 with a 74132 did NOT work
15:30 anonnumberanon rue_shop3 hey where do you get the pro mini for cheap good stuff?
15:39 rue_shop3 http://www.aliexpress.com/item/10pcs-lot-Pro-Mini-328-Mini-ATMEGA328-5V-16MHz-Free-Shipping-Dropshipping/1931550519.html
15:39 rue_shop3 these are the ones I regard to be good because they have the 6 pin isp right on them
15:40 rue_shop3 most of them dont have the 6 pin isp in their pinout
15:40 rue_shop3 see the double row of pads on the one end?
15:41 rue_shop3 http://www.aliexpress.com/item/10pcs-lot-module-ATMEGA328P-Pro-Mini-328-Mini-ATMEGA328-5V-16MHz-for-Arduino-5V-16M/32468781199.html
15:41 rue_shop3 seee!?
15:41 rue_shop3 the pinout is on the back, they didn't show it
15:43 anonnumberanon Thanks.
15:43 anonnumberanon That
15:43 anonnumberanon s a really sexy hardware.
15:46 anonnumberanon Last night I fought with two different usb to serial coverters, the small USB type ones with a header of 5 to 6 pins. None of it worked to load programs onto a bootloader ready atmega328 chip, then i used the one arduino uno I had and figured out how to load a program onto both chips (two weeks ago I had 5, gave them back to my teacher).
15:47 anonnumberanon Both are happily "blink"ing away right now, waiting for further nrf24l01 instructions. I do am sad I couldn't get the usb to serial converters to work.
15:49 deshipu I like the 3.3V version
15:54 rue_shop3 avoid usb to ttl that use CH340 and CP2102
15:54 rue_shop3 they both seem to have issues
15:55 anonnumberanon both cp2102
15:56 rue_shop3 with the cp2102, you may not be able to send full baud rate to it, you have to send in small bursts, otherwise the buffer seem to drop data
15:56 rue_shop3 so, if your typing to your avr in a terminal it'll be fine
15:56 rue_shop3 but if you write a program that sends a string, it wont be recieved properly
15:56 rue_shop3 aka, lots of missing characters
15:56 rue_shop3 this was tested with chip loopback
15:57 rue_shop3 its not an avr issue
15:57 anonnumberanon cause they d9n't have crystals on them or somthing?
15:57 rue_shop3 something is wrong with the handshaking or buffering in the cp2102
15:58 rue_shop3 I'v also had issues where plugging multiple usb-ttl converters into a machine caused them all to recieve the characters, not just the one it was sent to
15:58 rue_shop3 not sure where that issue lies
15:59 rue_shop3 I partly suspect linux drivers
15:59 rue_shop3 but the ones from china all have the same serial number, so ...
16:03 anonnumberanon I must have had a reset timing problem on mine. Has to do with the converter's RTS or DTR pins or something.
16:04 anonnumberanon I guess the next thing I'll attempt in this chapter is putting programs on bare atmega328 non bootloaded, using arduino as ISP, but for now I'm good to go with these two.
16:45 rue_shop3 I dont use any of the handshaking
16:45 rue_shop3 what did you need handshaking for?
17:43 anonnumberanon yeah but you're on avrC
18:01 rue_shop3 eek are you using it AS an arduino!?
18:04 anonnumberanon yes. First I used ArduinoISP library on the Arduino board to flash the bootloader to the bare chip. Then I connected the usb serial converter to flash a program to the bootloaded chip and that did not work. Then I used the arduino board to flash programs to the bootloaded chip and that worked.
18:05 anonnumberanon I'm doing the transition to straight avr C later down the road.
18:05 anonnumberanon Trying to figure out a way to get 3.3V power supply to the radio chips now.
18:13 anonnumberanon Not sure if 0.5 Watt resistors in a voltage divided would be good.
18:13 anonnumberanon divider*
18:18 Hyratel1 anonnumberanon, how much power do they draw
18:19 anonnumberanon computing that right now
18:21 anonnumberanon if not good I'll go lm317T
18:22 anonnumberanon The NRF draws ~900nA when powered down, and ~15mA when awake/sending.
18:22 anonnumberanon we're in the clear..
18:23 rue_shop3 with proper heatsink
18:24 rue_shop3 the 100mA limit does not work with no heatsink
18:31 anonnumberanon turns out R1 should be 0.52 * R2
18:36 Hyratel1 anonnumberanon, why not a fixed vreg?
18:36 Hyratel1 you can get 3v3 in to-92
18:37 anonnumberanon Hyratel1, i have a lm317 that could get me 3.3 (let me know if I'm correct) but I've never tried a voltage divider to power stuff so wanted to try that.
18:38 Hyratel1 is this battery operated?
18:39 anonnumberanon Installing on two micros, the sender and the receiver. Sender is 7.2V Nimh down to 5 with 7805, the receiver is a wall wart at 5V.
18:40 Hyratel1 are you worried about battery life?
18:41 anonnumberanon Hyratel1, no not right now I got two of these 3200mAh NiMh batteries to play with.
18:41 Hyratel1 mmkay
18:41 Hyratel1 you know the Downside to linear regulators, right?
18:41 Hyratel1 I in = I out
18:42 anonnumberanon Yes. They expand quite a lot of power to heat well I * (change in V)
18:42 Hyratel1 and H disip = (Vin-Vout ) * I
18:43 Hyratel1 discounting logic losses
18:43 Hyratel1 yes - they run as a transistor in the resistive region
18:43 anonnumberanon Oh.
18:44 Hyratel1 that's why
18:44 anonnumberanon I don't have any SMPS chips, except for my huge servo power supply that I just got.
18:45 anonnumberanon well huge power, very small size
18:45 anonnumberanon 15A, adustable V out to 35 or something.
18:47 anonnumberanon well it is a buck converter, so converts voltage downwards . I don't know if you know the first stage power supply that rue_shop3 has in his power supply project but that's what I got to run the buck converter from.
18:47 anonnumberanon http://www.amazon.com/gp/product/B00C9UUFHC?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
18:52 anonnumberanon Okay I need very small resistances for this time to forage into my trashpicked stuff.
18:57 anonnumberanon man i knew this was a good idea to unsolder these things, found 3 1.3R, almost positive they are power resistors.
19:07 anonnumberanon wow the resistors got really hot lol
19:09 anonnumberanon no wonder i passing 1A through lol
19:09 rue_shop3 thermal derating
19:11 anonnumberanon i must find 16R ones instead
19:14 anonnumberanon Luckily I opened the circuit immediately, checked the resistors and their values haven't changed.
19:15 anonnumberanon \O/
19:33 anonnumberanon I'm getting 3.59V I wonder if that's good for 3.3.
19:59 anonnumberanon rue_shop3, do the avr boards you use contain a 3.3v supply like the arduinos?
19:59 anonnumberanon I'm finding it a good thing to have on a board. Hooking up lm317 right now to get 3.3.
20:00 JEntrep I just looked up what AVR means for the first time.
20:00 JEntrep Advanced Virtual Risc?
20:00 JEntrep really?
20:01 JEntrep strange acronym to keep using when discussing small microprocessor boards, yeah?
20:01 anonnumberanon JEntrep, this is why I stay in this field.
20:02 JEntrep also ...
20:02 JEntrep the term microprocessor is out of date as well
20:02 JEntrep there are no macro-processors anymore
20:03 JEntrep cpu boards
20:03 JEntrep unless AVR is referring to a controller
20:03 JEntrep Automatic Voltage Regulator?
20:05 JEntrep anonnumberanon, what is the project?
20:06 anonnumberanon communication between two micros using nrf24l01 chips
20:06 anonnumberanon wireless
21:32 anonnumberanon pwr supplies finished, moving on to interfacing the modules
23:41 anonnumberanon Well it would appear that I got slightly sidetracked.