Reset Pin connection STM32F205RBT6 during debug & normal mode

aamirali641989 · ‎2014-02-04

Posted on February 04, 2014 at 13:38

I had connected 0.1uF to reset pin which was creating problem while debugging with ulink2 on keil. This was given in datasheet.

But on removing this capacitor from reset pin , debugger works fine & running. But when I try to run my code without debugger i.e directly with power to check how it work in real situation.

Code does not run. But when I connect debugger only it runs as debugger pulls reset pin which causes MCU to come out of reset state.

How to correct that issue

chen · ‎2014-02-04

Posted on February 04, 2014 at 13:59

Hi

''I had connected 0.1uF to reset pin which was creating problem while debugging with ulink2 on keil''

''But on removing this capacitor from reset pin , debugger works fine & running.''

''Code does not run. But when I connect debugger only it runs as debugger pulls reset pin which causes MCU to come out of reset state.

How to correct that issue''

I think you need to put a resistor from power to the reset pin and the capacitor between the reset pin to ground. This forms an RC and does a delayed reset for normal (without debugger operation).

When you run with the debugger - it has some control of the reset line.

Tesla DeLorean · ‎2014-02-04

Posted on February 04, 2014 at 14:19

100nF and a 10/100K pull up on NRST shouldn't be an issue. Look for some other problems, either with the design of the board, or the components actually being used. Check that this 100nF (0.1uF) is actually what it purports to being, and not a short or something.

For RESET issue check specifically the analogue supplies, then look at the other supplies, and voltages/capacitances at VCAP pins.

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aamirali641989 · ‎2014-02-04

Posted on February 05, 2014 at 06:30

Thanks 4 ur answers.

1. I haven't connected 100K pull-up on reset pin. As I thought reset pin is inetrnally pulled up.

I will try by 100K pull-up & 0.1uF bypass across reset pin & see its response.

2. But I think on connecting 100K & 0.1uF, it causes problem on debugging as reset is used.

I am using keil/ulink2/swd for debugging