Stop watch app inventor

I'm new user of App inventor. I need small stopwatch. Basic function: - set time ex. 25 开发者_运维知识库min (if time=0;alarm=true) - start time - reset time (if you want reset time you will see the comfir box (yes or no)

Can anybody show me what block I must use to create it ?. Sorry for my English.

Here is a link to a discussed about this in the App Inventor Coffee Shop. https://groups.google.com/forum/?fromgroups#!topic/appinventor/qrhfCSv4US0

This block will need a label, and a timer. You can choose to make it in seconds or milliseconds by changing the clock functions.

Here is an example. The user enters the duration into the minute and second textboxes. Then they press the button. The timer interval is set to the duration converted to milliseconds. Then the timer is enabled. After the duration is up, Clock1.timer fires. The notifier shows an alert that the timer finished and the timer turns off. To reset the timer, just set Clock1.timerEnabled to true.