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STM32F4 does not self-reset on power up; BOOT0 is tied to GND

Question asked by barrows.geoffrey on Apr 16, 2013
Latest reply on Jul 31, 2015 by Lenora
Hello,

I'm using an STM32F415 in an LQFP64 package on a new PCB design. BOOT0 is tied to ground. I can program the STM32 (using IAR and the ISP designed by ST) and get it to run using the IDE. The NRST pin is floating on the PCB, though connected to the JTAG of course. However when I remove the ISP the processor no longer resets on it's own. I can, though, get the processor to run by shorting NRST to GND.

I am pretty sure this is something to do with the PCB design itself- I have another "old" PCB design, also using the same processor, and some code that runs fine on that old PCB design. (e.g. it resets on it's own just fine.) But when I take that known code and program it into the new PCB design I get the same result- it runs when the ISP is connected and prompted in the IDE, and runs when I manually short the NRST to GND, but does not reset to start running on it's own.

I have already fabricated a second of the "new" PCB designs to rule out a bad processor. Same result.

I even tried physically desoldering and bending up the NRST pin to eliminate the possibility of capacitive (or whatever) loading on that pin. Same result.

I do have the requisite 0.1uF bypass capacitors, 2.2uF regulator capacitors for VCAP, and 4.7uF big bypass capacitor, and VDDA and VSSA are connected respectively to VDD and GND. This is for both the troublesome "new" and verified "old" PCB designs. BOOT0=GND on both designs.

Has anyone experienced something like this before, or have any suggestions?

Thanks!

Geof

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