watchdog timing

[lpcware]

Content originally posted in LPCWare by borik2003 on Wed Nov 24 04:40:09 MST 2010
Hi

I am trying to write watchdog function with programmable time out

[B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055][LEFT]void[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] [B]WDTInit[/B]([/SIZE][SIZE=2][COLOR=#005032][SIZE=2][COLOR=#005032]uint32_t[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] timeout_us )
{
[/SIZE][SIZE=2][COLOR=#005032][SIZE=2][COLOR=#005032]uint32_t[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] pclk_wdt = __WDT_OSC_CLK;
[/SIZE][SIZE=2][COLOR=#005032][SIZE=2][COLOR=#005032]uint32_t[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] tempval = 0;

[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]//[U]Selectable[/U] time period from (TWDCLK × 256 × 4) to (TWDCLK × 2^24 × 4) in multiples of TWDCLK × 4.[/COLOR][/SIZE][/COLOR][/SIZE]
[SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f] [/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]
tempval = timeout_us;
[/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]if[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2](!((tempval >= 256) && (tempval <= 16777215)))
{
[/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]return[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2];
}

[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]//wdt_osc_clk = [U]Fclkana[/U]&#8260;(2 × (1 + DIVSEL)) = 7.8 kHz to 1.7 MHz (nominal values).[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]
LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTOSCCTRL[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0 | (SYSCON_WDT_FREQ_3_4 << 5); [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]//[U]Fclkana[/U]=3.4Mhz,DIVSEL = 0 => wdt_osc_clk=1.7 MHz[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKSEL[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = SYSCON_WDT_CLK_WDTOSC; [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Select clock source[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKUEN[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0x01; [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Update clock[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKUEN[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0x00; [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Toggle update register once[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKUEN[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0x01;
[/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]while[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] ( !(LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKUEN[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] & 0x01) ); [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Wait until updated[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDTCLKDIV[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 1; [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Divided by 1[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]PDRUNCFG[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] &= ~(0x1<<6); [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Let WDT clock run[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]
&#12288;
[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Enable clock to WDT[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_SYSCON->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]SYSAHBCLKCTRL[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] |= (1<<15);

wdt_counter = 0;

[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]//Enable the WDT Interrupt[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]NVIC_EnableIRQ([/SIZE][I][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]WDT_IRQn[/I][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2]);

LPC_WDT->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]TC[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = tempval;

LPC_WDT->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]MOD[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = WDEN | WDRESET;[/LEFT]
[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f][LEFT]//LPC_WDT->MOD = WDEN;[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]
LPC_WDT->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]FEED[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0xAA; [/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Feeding sequence[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]LPC_WDT->[/SIZE][SIZE=2][COLOR=#0000c0][SIZE=2][COLOR=#0000c0]FEED[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] = 0x55;

[/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]return[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2];[/LEFT]
}


[B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055][LEFT]int[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] [B]main[/B] ([/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]void[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2])
{
InitPLLIRC(48);

[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]// Set port for LED to output[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]SetupGPIO(LED_PORT,LED_BIT,GPIO_DIR_OUTPUT,GPIO_FUNC_MASK,GPIO_FUNC_0);

WDTInit(100000);[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f]//WDT_TIMEOUT_US(50000));[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][LEFT]
&#12288;
SetGPIOBit(LED_PORT, LED_BIT);
delay32_Us(0, 100);
ClrGPIOBit(LED_PORT, LED_BIT);

[/SIZE][B][SIZE=2][COLOR=#7f0055][SIZE=2][COLOR=#7f0055]while[/B][/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] (1)
{[/LEFT]
[/SIZE][SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f][LEFT]    //no feeed to get wdt reset[/LEFT]
[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2]}

i send to [B]WDTInit() value =100,000 that means (1/1.7Mhz)*100,000*4 = 235.3ms timeout[/B]

[B]but what i get is time out of 174ms ( i see it between led toggles)[/B]

[B]what i am missing ?[/B]
[/SIZE][/SIZE]

[lpcware]

Content originally posted in LPCWare by NXP_Europe on Wed Nov 24 14:55:39 MST 2010
Hello borik2003,

be sure that the calculation of the WatchdogTimer is done on the edges of the spec's, otherwise unforseen resets of the program are given.

[lpcware]

Content originally posted in LPCWare by borik2003 on Wed Nov 24 06:14:59 MST 2010
thanks,

//========

[SIZE=2][COLOR=#3f7f5f][SIZE=2][COLOR=#3f7f5f][LEFT]Remark for [U]watchdog[/U] oscillator: Any setting of the FREQSEL bits will yield a [U]Fclkana[/U] value within ±40% of the listed frequency value. The [U]watchdog[/U] oscillator is the clock source with the lowest power consumption. If accurate timing is required, use the IRC or system oscillator.[/LEFT]

//=======================
[/COLOR][/SIZE][/COLOR][/SIZE]

[lpcware]

Content originally posted in LPCWare by gbm on Wed Nov 24 05:38:46 MST 2010
You are missing the fact that the precision of WDTOSC is very low.