lpcware

Does setting CRP2 in internal flash disable booting from USB and protect our software?

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by iemc on Thu Oct 15 14:00:46 MST 2015

Chips: LPC4357 and LPC4337 (1MB internal flash)
Manual: UM10503.pdf Rev. 1.9 — 18 February 2015

In the manual these two flow charts are the same.

Page 51: Fig 13. Boot process flowchart for LPC43xx parts with flash

Page 53: Fig 14. Boot process for parts without flash

Assuming P2_7 is high and valid user code is present in the internal flash (6.4.4.1 Criterion for Valid User Code), where in Fig 13 does the chip boot from the internal flash?

If the boot ROM checks BOOT_SRC first then would it be possible to boot from USB and bypass CRP2?

This would allow someone to put their own code into RAM by adjusting the boot pins P2_9, P2_8, P1_2 and P1_1 to boot from the USB. Their code could then extract the software from the internal flash.

Hopefully this is not the case and Fig 13 is incomplete.

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