SDK14.2 DFU power cycle issue

Question

Situation: Trying to upgrade previous versions of the SD and BL (V3.0.0) to (V5.0.0)
Problem: device power cycles after a new application is flashed to the device into the V5.0.0 SD and BL. 
 Steps: 
 
 Take target device, including dev board, and program SD3.0.0 and V3.0 buttonless bootloader 
 DFU an App appropriate for SDV3.0.0 and run it. 
 DFU the new SD and BL (V5.0.0) package to the device 
 DFU an App appropriate for SDV5.0.0 and run it 
 
 Result of performing all 4 steps is that the device keeps power cycling. If you skip step 2, the procedure works and the device functions as desired. 
 I am guessing that there is some internal register that is written to during the DFU process in step 2, and that this register is not being updated to accommodate the position changes due to the larger SD. 
 Is there a work around?

Sensorion · Accepted Answer

The error was an application level error not a boot loader error. The boot loaders for both the SD v3.0.0 and SD v5.0.0 work correctly as does the package used to update a target chip from v3 to v5. The error was in the interaction between the FDS initialization in the v3 app and then the v5 app. 
 The application I was using for SD v3(App3) declared 8 virtual pages of FDS memory space. The new version based on SD v5(App5) only had 4 pages declared. When App3 was flashed to the chip it initialized 8 virtual pages, 7 data and 1 swap. These pages are not erased during the subsequent DFU processes. When App5 is installed and run it tries to initialize the FDS system and finds 4 initialized data pages but no swap page. This creates a no memory error, which causes a system reset. 
 The solution was to set the number of virtual pages in App5 to 8. 
 I have not experimented with this but perhaps it is possible that changing the number of virtual pages in this manner could result in the same error even without going through the update process. Also the system should have some means of dealing with the situation where it finds several data pages and no swap page.

SDK14.2 DFU power cycle issue

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