RSIR LPC2364/66/68

You should clear the Reset Source Identification Register after you have read the value. The following statement clears it.

  RSIR = 0xF;            //     Clear RSIR flags

For the NXP user's manual: Writing a 1 to any of these bits clears the corresponding read-side bit to 0.

You should clear the Reset Source Identification Register after you have read the value. The following statement clears it.

  RSIR = 0xF;            //     Clear RSIR flags

For the NXP user's manual: Writing a 1 to any of these bits clears the corresponding read-side bit to 0.

My code looks this:

      printf("\n\rPowerup Source [%04X]: ",RSIR);
      if(RSIR&(1<<0)) {printf("POR "); RSIR|(1<<0);}
      if(RSIR&(1<<1)) {printf("EXTR ");RSIR|(1<<1);}
      if(RSIR&(1<<2)) {printf("WDTR ");RSIR|(1<<2);}
      if(RSIR&(1<<3)) {printf("BODR ");RSIR|(1<<3);}

I clear the bits individually.

Then I also tried this code:

      rsir=RSIR;
      RSIR=0x0f;
      printf("\n\rPowerup Source [%04X]: ",rsir);
      if(rsir&(1<<0)) {printf("POR ^");}
      if(rsir&(1<<1)) {printf("EXTR ");}
      if(rsir&(1<<2)) {printf("WDTR ");}
      if(rsir&(1<<3)) {printf("BODR ");}

no difference, output is:
Powerup Source [000B]: POR EXTR BODR

Any other idea?

I have used the code below in the BLINKY example of the MCB2300 Board and it just works fine:

  char lcd_txt[20];
    :
  sprintf (lcd_txt, "Reset Src=%X", RSIR);
  RSIR = 0xF;            //     Clear RSIR flags
  lcd_print (lcd_txt);

I have tried your code on MCB2300 with LPC2378 and it works as expected.

After Power-on Reset the value of RSIR = 0x03 and the register is cleared when writing 0x0F into it. Also after asserting External Reset the value in RSIR = 0x02 which is also correct.

It seems that on your HW the BODR bit is set (Brown-out detection). Maybe you have some problems with the power supply.

Thank you for your effort. I will have a look at my hardware.
P.