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iOS touchesEnded for multitouch single finger release

If you need to know which finger actually were lifted from screen when doing a multiple touch tracking, you need to check the phase variable from UITouch to see if it has been actually lifted from screen. If the single touch has ended, it’s phase will be UITouchPhaseEnded

Normally when you lift one finger, the touchesEnded is called with a set of all active touches. I wish it would be a set of only touches that have ended.

Example code:

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
NSSet *allTouches = [event allTouches];

for (int zz=0;zz<[allTouches count];zz++)
UITouch *touch = [[allTouches allObjects] objectAtIndex:zz];

CGPoint touchPos = [touch locationInView:self];

if (touch.phase==UITouchPhaseEnded)

Rant: my Apple fanboyism is starting to crack

Really, really annoying things with Apple products, every day:

– My iPhone 6S has battery malfunction (shuts down at 40% of battery level and refuses to start) and is under warranty change. However the repair shops cannot get the batteries because of high demand. Apple calls this issue affecting small amount of iPhones. I doubt it.
– Using “night mode” which mutes the iPhone automatically during night. However when plugging the charging cable makes “pling” noise when everything else is muted. Really nice because when rest of family is sleeping and you want to charge overnight.
– Forget to put the phone on charging. Wakes me up at morning still, good boy. To shut off the alert I need to enter my 6 digit passcode (because the phone rebooted). Why I need to enter passcode on reboot? Isn’t the fingerprint scanning enough secure?! Trying to tap the passcode without eyeglasses immediately when woken up is like a nasty test.
– Apple releases new Macbook (finally) and I was waiting to replace my old Macbook with brand new. Apple raises prices and removes USB ports and SD card slot on new model. Well played, Apple.
– I purchase previous model Macbook because of previous issue and think 128GB is enough for the “internal” SSD. I was wrong, installed Xcode and constantly running out of disk. Irritating me with nags. The internal SSD cannot be replaced. Need to use external hard disks.
– My iPad wants to make OS upgrade but I don’t want to do it. Asks it every day. With two dialogs. I. DON’T. WANT. TO. UPDATE. PLEASE. LET. ME. CONTINUE. Solution: there isn’t any real solution, but you can hack it.

Next laptop: back to Windows? Really?!

Useful commands

GIT: Show changed files in last commit
git log --name-only --pretty=oneline --full-index HEAD^^..HEAD | grep -vE '^[0-9a-f]{40} ' | sort | uniq

GIT: Show file history
git log -p filename

BASH: Find word in files
grep -R "word_to_search" *

Battery powered Elektron machines

Can Analog Four or Analog Rytm be powered from battery?

Elektron support answers:

“If the voltage goes below 10V the analog electronics will stop working but the OS still runs down to 6V. Max voltage is 15V but only for a short time so don’t push it.”

So 3 cell Lipo works just great. Don’t forget low battery alarm!

Dshot times & frequencies

One frame (“pulse”) is 16 bits long.

It contains

  • 11 bits of throttle value (2047 separate throttle positions available)
  • 1 bit telemetry request
  • 4 bits of CRC checksum.

The options for Dshot speeds are:

Dshot 600 600 kbit per second Single frame: 26.66 uS (microseconds) Absolute maximum update frequency 37.5 kHz
Dshot 300 300 kbit per second Single frame: 53.3 uS (microseconds) Absolute maximum update frequency 18.75 kHz
Dshot 150 150 kbit per second Single frame: 106.6 uS (microseconds) Absolute maximum update frequency 9.3 kHz

Just a reminder: multishot pulse is max 25 uS long, multishot protocol allowing max 32kHz update speed.

For “old” methods (dshot, oneshot), see this link.

Tip: Serial ports in microcontrollers

- Use software serials ONLY for debugging. Software serials are not reliable.
– Use hardware serials primarily for interfacing with devices (GPS etc.)
– Prepare for debugging port in your design
– Program the uC through native programming method (ISP, ICSP) if you don’t have several hardware USARTs
– Make all sorts of cross-compatible adapters and cables for easy debugging
– Use two laptops for development: one for plainly debugging

When picking uC, make sure you have plenty of hardware serials. Usually one isn’t enough.