Hello Jeremy, thanks for the reply,
I did a small robot controlled by the computer using a pair of wixels to communicate. Wixel in robot also controls the pulses to stepper motors. A few months ago I opened a topic here to show the result:
After that I made some improvements in robot and now would like to add a distance sensor in it, so I bought the HC-SR04.
From what I saw in other topics, I was wondering what would be tricky to measure intervals of less than millisecond, so I thought I’d create my own ticks using something like the code below. Certainly would not be very accurate, but perhaps solve, then I can put the result here.
My ticks are loops in a while statement. At startup I make an estimate of how many “ticks” per second can be produced.
uint32 ticks4sec = 0;
#define BIGnumber 1000000
void initTicks(){
uint16 ms;
uint32 tk;
tk= BIGnumber;
ms= getMs();
while(tk)
tk--;
ms= getMs()-ms;
if(ms)
ticks4sec = (BIGnumber*1000) / ms;
// else need a bigger number
}The idea is count “ticks” during pulse and then calculate time based on estimate made before:
#define pnTrigg P0_0
#define pnEcho P0_1
uint32 ultraSonicTicks()
{ uint32 tcks=0;
pnTrigg = 0;
delayMicroseconds(2);
pnTrigg = 1;
delayMicroseconds(10);
pnTrigg = 0;
LED_RED(true);
while (!pnEcho); // <---- Problem here
LED_RED(false);
LED_YELLOW(true);
while(pnEcho)
tcks++;
LED_YELLOW(false);
return tcks;
}But is not working, first while never stop and now im trying find out why. Bellow my startup code:
void main()
{
systemInit();
usbInit();
radioComInit();
initTicks();
// pin 00 to digital output - trigger
setDigitalOutput(00, LOW);
// pin 01 to digital input - echo
setDigitalInput(01, true);
. . .
}Since Wixel pins are not 5V tolerant, pin P0_1 is being fed through a voltage divider as showed in user guide at pololu.com/docs/0J46/5.b
About interrupts, I have no experience, but I would really like to learn to use. I have searched on the matter but it would be very instructive to see a specific code example for Wixel.
regards