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mailmail9117
mailmail9117
Associate
January 8, 2013
Question

STM32F205 JTAG fuse boundary scan

  • January 8, 2013
  • 2 replies
  • 1160 views
Posted on January 08, 2013 at 23:14

Does the so-called ''JTAG fuse'' prevent me from using boundary scan to toggle IOs?

DP

#rtfm #jtag-fuse-ip-read-protection
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2 replies

Uwe Bonnes
Uwe Bonnes
Chief
January 9, 2013
Posted on January 09, 2013 at 11:19

STM32 has no Fuses. However Code can configure the Pins used for JTAG/SWD for other uses, resulting no JTAG/SWD access after the code configuring the pins has been executed.

Tesla DeLorean
Tesla DeLorean
Guru
January 9, 2013
Posted on January 09, 2013 at 13:42

It has options bytes, which have an equivalent function.

From PM0059

�? Level 2: Disable debug/chip read protection

 

When the read protection Level 2 is activated by writing 0xCC to the RDP option byte,

 

all protections provided by Level 1 are active, system memory and all debug features

 

(CPU JTAG and single-wire) are disabled when booting from SRAM or from system

 

memory, and user options can no longer be changed.

 

Memory read protection Level 2 is an irreversible operation. When Level 2 is activated,

 

the level of protection cannot be decreased to Level 0 or Level 1.

 

 

Note: The JTAG port is permanently disabled when Level 2 is active (acting as a JTAG fuse). As a consequence, boundary scan cannot be performed. STMicroelectronics is not able to perform analysis on defective parts on which the Level 2 protection has been set.

 

 

Do your boundary scan and testing BEFORE programming the device. Place raw unprogrammed devices, or where you can programmatically enable RDP via the application or boot loader.
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