1. I am using STM32F205, with serial wire debug, composing reset, clk, data & gnd pins. 2. Whenever I connect debugger my code runs perfectly. But without debugger, sometimes code just don't run. I am toggling a pin which never happens. it happens only sometimes. 3. No other clk init is done, so default 16Mhz clck, as soon as MCU power up, I keep on toggling pin. No code in between so couldn't be memory access other or anything. So pin toggle. 3. I have 0.1uf cap on reset pin & 10k pull down on boot pins. 4. However I have left swclk & swdata pins float. 5. I had checked below link & connected 10k pull down to clk & 10k pull-up to data. support.code-red-tech.com/.../HardwareDebugConnections
6. I will check multiple times before reaching conclusion, but any idea on this.