In previous update, we talked about the iPen 2 calibration app, calibrator, which is built based on iPen 2 SDK. So if we want to debug iPen or test its performance, the best way is to observe its drawing behavior inside calibrator, and then deal with foreseeable problems. And once the problems are resolved inside calibrator, the SDK is fixed at the same time. It’s like both calibrator and SDK have the same engine. In the past few months, we had observed the drawing lag in calibrator, and tried to fix it with several hardware and software modifications. We’re glad we finally have the answer today.
The following videos show no lag during drawing test. You will also notice the stylus draws dots, instead of lines for demo purpose. In order to kill the lag and optimize drawing stroke, we have to increase the number of PPS (packet per second) sent from iPen receiver, and make sure iOS can catch those packets on time. Generally speaking, each packet represents one single dot. iPen 2 can generate 100 dots per second if we set PPS = 100. iPen 1 has only 30 PPS due to hardware restriction; and iPad touch event has around 60 PPS based on our calculation. This means iPen 2 has potential to draw faster than finger touch or any capacitive stylus. However, this is a complicated subject. We will explain it later on.
Live long and prosper \\ //
iPen 2 straight line testing in calibrator dot mode - no jitter
iPen 2 angle agnostic testing in calibrator dot mode
iPen 2 pressure sensitive testing with calibrator in dot mode