sw_delay

back to Command Reference / Time

Description

Pauses the program for the amount of time (in milliseconds) specified as parameter. There are 1000 milliseconds in a second.

Notes:

• sw_delay() uses loops and NOPs (in contrast to delay()). It therefore does not require the TIM4 interrupt to be active.
• since sw_delay() does not use the 1ms interrupt, it becomes inaccurate if a high interrupt load is present

Inclusion

• defined in sw_delay.h
• auto-loaded in main_general.h
• no #define required

Syntax

sw_delay(ms)

Parameters

• input:

  • ms: the number of milliseconds to pause (unsigned long)

• output:

  • none

Returns

• Nothing

Example Code

The below code toggles pin PD0 every 500ms.

#include "main_general.h"

void setup() {
  pinMode(&PORT_D, 0, OUTPUT);
}

void loop() {
  pinOutputReg(&PORT_D, pin0) ^= 1;
  sw_delay(500);
}

Relevant Tutorial

• tbd

Notes and Warnings

While it is easy to create a blinking LED with the sw_delay() function, and many sketches use short delays for such tasks as switch debouncing, the use of sw_delay() in a sketch has significant drawbacks. No other reading of sensors, mathematical calculations, or pin manipulation can go on during the delay function, so in effect, it brings most other activity to a halt. For alternative approaches to controlling timing see the millis() or setTimeout() functions. More knowledgeable programmers usually avoid the use of sw_delay() for timing of events longer than 10’s of milliseconds unless the sketch is very simple.

Certain things do go on while the sw_delay() function is controlling the STM8 however, namely interrupt handling and automatic hardware functions. For example, interrupt-diven serial communication and timer-based PWM output are maintained. However, at high interrupt load, sw_delay() becomes inaccurate.

See also

• sw_delayMicroseconds()
• sw_delayNOP()
• delay()
• delayMicroseconds()
• millis()
• micros()
• flagMilli()
• clearFlagMilli()
• setTimeout()
• checkTimeout()
• startStopwatch()
• getStopwatch()
• startClock()
• stopClock()
• attachInterruptMillis()
• detachInterruptMillis()