LPC845 not power up without manual reset

[jtro]

MCU: LPC845M301JBD48

I'm working on LPC845-BRK board and observed that when I'm powering my board it won't execute my application and it always required to press Reset key to start program.

Is there anything required for POR. I don't want to connect external circuit for reset.

I'm not using RESET pin. I have set output low as per unused pin guideline .

[luizspa]

The rise time of your power supply must fit the time requirements described in the page 46 of the datasheet. The time between 1.4V and 1.8V must not exceed 8ms. The solution is to add a RC circuit in the reset pin in order to keep the reset input below 0.3*VDD when the power supply reaches 1.8V. 

[BlackNight]

Hi jtro‌,

I don't observer something like this with the LPC845-BRK boards I'm using. Does it happen for you with the SDK (e.g. blinky) application too? And I assume you don't have any additional hardware attached to the board (I ask because depending on external hardware that external hardware needs some time to power-up too).

I hope this helps,

Erich

[xiangjun_rong]

Hi,

I have checked the Reset circuit for LPC845-BRK schematics, it appears that the Reset(PIO0_05) circuit does not use RC circuit, there is NOT any capacitor, there is only R19 pull-up resistor, how about connecting a capacitor between PIO0_05 pin to GND?

BR

XiangJun Rong