#avr Logs

May 26 2019

03:45 AM rue_shop1: tip of the day: when using interrupts, it helps to turn them on.
07:06 AM polprog: hey rue_mohr, check it out: https://i.ibb.co/BTCzRxJ/IMG-20190526-135820.jpg
07:43 AM polprog is now known as plpg
09:28 AM tecdroid: hi there.. i need an idea how to solve a tiny problem with my electronics. i'm using an attin25 with a software uart. any time i connect this uart to my usb2ttl cable, my attiny gets powered and turns on.. which it shouldn't
09:31 AM nohit: don connect the Vcc of your cable, just rx, tx and gnd
09:31 AM tecdroid: i did
09:32 AM tecdroid: i don't even have a connection for vcc on my uart adapter
09:34 AM plpg: show us what youve got
09:37 AM nohit: take a pic of your setup
09:42 AM tecdroid: https://ibb.co/DLPVzSz
09:42 AM tecdroid: sorry, took some minutes to recover it. i tried to exchange with t44 just because a crystal should make it a little more stable.. but problem is the same there
09:43 AM plpg: ok, and how do you connect it
09:43 AM plpg: what wires go from the usb adatper to the board
09:44 AM tecdroid: it's a usb2ttl cable with simple pin connectors
09:44 AM tecdroid: want to use that board to power up/down a raspberry pi
09:48 AM tecdroid: like that one: https://ameridroid.com/products/pl2303hx-to-usb-ttl-cable-for-arduino connecting ground and the green cable makes my led turn on
09:49 AM plpg: PB0 is aref.. im not sure if its possible that aref is connected to VCC internally and that conducts
09:49 AM plpg: but im skeptical
09:50 AM plpg: i dont see any other reason why would connecting TX cause the VCC to go up
09:50 AM tecdroid: connecting the tx cable to pb1 has same effect
09:50 AM plpg: you could try AC coupling the uart line(s) for a quick and dirty solution
09:51 AM plpg: i think i know whats wrong
09:51 AM tecdroid: i thought of an opto coupler.. but maybe a resistor will do the job, too
09:51 AM plpg: its probably leaking thru the pin ->|- VCC, upper protection diode
09:52 AM plpg: just put some ceramic caps on the uart, pull the RX up to 5V on the avr side with a resistor
09:52 AM plpg: it should work..
09:54 AM tecdroid: caps to ground?
09:55 AM plpg: no, a cap between the uart input and the avr pin
09:56 AM tecdroid: like some kind of high pass?
09:56 AM plpg: yes,
09:56 AM plpg: its called AC coupling
09:57 AM tecdroid: sounds interesting. i'll try.
09:58 AM tecdroid: see you then.
10:00 AM plpg: tecdroid: http://tinyurl.com/yxbdfw8q
10:01 AM plpg: ac couples schmitt trigger
10:01 AM plpg: coupled*
10:21 AM plpg is now known as polprog
12:17 PM rue_mohr: mornig
12:20 PM rue_mohr: tecdroid, do you have an arduino bootloader on it?
12:21 PM tecdroid: see you then.nope nod yet
12:21 PM rue_mohr: polprog, the reset line on your pi isn't tried high
12:22 PM rue_mohr: tecdroid, ok
12:22 PM polprog: huh?
12:22 PM rue_mohr: just woke up, cant make heads or tails of your power control yet
12:22 PM rue_mohr: your pi
12:22 PM rue_mohr: <polprog> hey rue_mohr, check it out: https://i.ibb.co/BTCzRxJ/IMG-20190526-135820.jpg
12:22 PM tecdroid: still programming it via avr dragon
12:23 PM rue_mohr: tecdroid, and you have the dragon disconnected when your operating the circuit?
12:23 PM tecdroid: yes
12:23 PM rue_mohr: cause the isolation of the dragon has a really bad reputation
12:23 PM tecdroid: yeah, i know what you mean XD
12:24 PM polprog: rue_mohr: the reset is in the bottle in the cupboard ;)
12:24 PM tecdroid: my board doesn't even have an isp
12:24 PM rue_mohr: polprog, your running WINE too eh? hmmm
12:24 PM polprog: :P
12:25 PM rue_mohr: tecdroid, is it possible that you have a glitch in your keepalive line?
12:25 PM rue_mohr: wait
12:26 PM rue_mohr: wait
12:26 PM rue_mohr: where is the pullup on your reset pin?
12:26 PM rue_mohr: there should be like a 10k pullup on reset
12:28 PM tecdroid: it's not neccessarily needed.
12:28 PM rue_mohr: heh, aliexpress is taloring ads to my old searches
12:28 PM rue_mohr: tecdroid, yea you need it, add one and see
12:29 PM rue_mohr: hmm, about $1ea.... what they got...
12:30 PM rue_mohr: yea 85 runs about $2ea
12:30 PM tecdroid: rue_mohr: the controller has an internal pullup on the reset pin. so as long as i don't use reset pin, i don't need an external one
12:30 PM rue_mohr: no that has to be turned on
12:31 PM rue_mohr: try with one for a bit, its a far shot, also, try locking the keepalive on via hardware and see if you still get the reboot issue
12:32 PM rue_mohr: oh, the 25 is a short 85
12:32 PM tecdroid: i don't have a reboot issue
12:32 PM rue_mohr: iiinteresting
12:32 PM rue_mohr: <tecdroid> hi there.. i need an idea how to solve a tiny problem with my electronics. i'm using an attin25 with a software uart. any time i connect this uart to my usb2ttl cable, my attiny gets powered and turns on.. which it shouldn't
12:32 PM * rue_mohr squints
12:33 PM rue_mohr: oh
12:33 PM rue_mohr: ok, well you know about the internal diodes, right?
12:34 PM rue_mohr: the voltage difference from ground to the RX pin when its high with litterally, feed the vcc of the controller
12:35 PM rue_mohr: if your going to capacitor couple it, make sure its a small cap
12:35 PM rue_mohr: what baud rate are you using?
12:36 PM rue_mohr: you could also use another BS170 to buffer the RX
12:36 PM rue_mohr: and, because its software serial anyhow, invert the line
12:36 PM rue_mohr: tecdroid, you there?
12:36 PM rue_mohr: ok, shower and breakfast for me then
12:40 PM polprog: [19:29] rue_mohr: ok, well you know about the internal diodes, right?
12:40 PM polprog: knew that lol
12:40 PM rue_mohr: :) hey, I just woke up...
12:41 PM polprog: that must be it
12:41 PM polprog: the rue says soo
12:41 PM rue_mohr: I think the fet is the best way out
12:41 PM tecdroid: sorry, back
12:42 PM tecdroid: just gave the external reset pullup a chance with no effect
12:43 PM polprog: rue_mohr: the fet? youre talking to me or tecdroid ?
12:43 PM rue_mohr: tecdroid,
12:44 PM rue_mohr: he can isolate the RX line thats backfeeding power to the controller with a fet
12:44 PM rue_mohr: and he's already using a BS170
12:45 PM polprog: yeah
12:45 PM polprog: i suggested a cap as well
12:45 PM rue_mohr: yup
12:45 PM polprog: thats a funnu issue tho :p
12:45 PM rue_mohr: ugh, the BS170 is 1.2R rdson
12:45 PM rue_mohr: iirc there is no smt version of the 2n7000
12:46 PM rue_mohr: tho wtf, there is one in the datasheet
12:46 PM rue_mohr: huh
12:46 PM polprog: damn, if i had some 2n7000 but strong enough to drive the filiment
12:46 PM rue_mohr: ok I give up, its 1.2R also
12:47 PM rue_mohr: your 60N55 was better than that tho
12:47 PM polprog: i need to measure that more in depth
12:48 PM polprog: tests with a 100R power res were okay
12:48 PM rue_mohr: I still say use a trnsformer :)
12:48 PM polprog: ill give that a shot
12:50 PM tecdroid: sorry, i'm not as fast as you are because i'm flashing and re-flashing my attiny XD
12:50 PM polprog: lol why
12:50 PM polprog: program wont fix your issue :p
12:51 PM tecdroid: well not if you don't change programming.
12:52 PM tecdroid: the capacitor on my rx at least prevented the whole thing from getting powered by rs232
12:58 PM polprog: good
01:09 PM rue_mohr: will it carry the datarate your using is the next question
01:10 PM rue_mohr: polprog, cant wait to be able to profile filters
01:10 PM rue_mohr: want to do a PID filter and see if I'm right about what I suspect
01:17 PM rue_shop3: heh, if I only wait 250ms for a pulse, I cant go down to 1hz
01:18 PM rue_shop3: breakfast
01:34 PM polprog: bon apetit
02:08 PM circuit is now known as elektrinis
03:39 PM polprog: i wish i could make a damn VCO
04:00 PM polprog: hmm that looks pretty simple
04:00 PM polprog: https://commons.wikimedia.org/wiki/File:Voltage_controlled_oscillator_(VCO)_diagram.jpg
04:02 PM polprog: looks like the mos is just taking away some current when out2 is high
04:02 PM polprog: i guess 'in' is the control voltage
04:02 PM polprog: hmm
04:02 PM polprog: might experiment with it
04:02 PM polprog: anw snap, i havent bought the opamps
08:33 PM rue_mohr: polprog, what params for the vco?