<!--This only works in android mobile phone-->
<a href="geo:0,0?q=myaddress+encode)__" target="_blank"> Open Map,I am here. </a>
<!--This works under iphone--> <a href="http://maps.apple.com/?q=myaddress+encode" target="_blank">Open Map, I am here. </a>
Here are the pages list:
How to launch Google Maps on iPhone via web link?
Getting Safari to auto open Google Maps App
How to lauch Google Maps App by Web Url under the android