https://devzone.nordicsemi.com/f/nordic-q-a/18417/is-the-flash-page-no-is-continuousFor example: region 0: 0x00000 -&gt; 0x1b000 region 1: 0x1b000 -&gt; 0x40000 In region 0: the first page(1024 bytes) is 0x400=1024 from 0x0000 -&gt; 0x400 , ERASEPCR0 must be 0 or 1 In region 1: the first page(1024 bytes) is 0x1b000 -&gt;0x1b400 ,ERASEPCR1en-USTelligent Community 13Fri, 16 Dec 2016 02:33:05 GMThttps://devzone.nordicsemi.com/thread/71061?ContentTypeID=1Fri, 16 Dec 2016 02:33:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a2cfc03b-2218-4b61-a303-9e5cbec4f8abligang<p>the value is 108*1024. that is why I can not erasing ok!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/71060?ContentTypeID=1Thu, 15 Dec 2016 12:53:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f7f7ba24-80f5-4366-9459-bc6703f507c9Petter Myhre<p>The first page would be 108. This is however where you usually have your application, and I don&#39;t recommend erasing part of the application.</p><div style="clear:both;"></div>