JohnOH
commented
1 year ago delayMicroseconds is commented out in ATTinyCore/avr/cores/tiny/wiring.c
There is a version in Arduino.h as follows:
static inline void delayMicroseconds(uint16_t us) { // if us is a compile-time constant result is accurate to 1 cycle if (__builtin_constant_p(us)) { _delay_us(us); return; }
// when us is not known at compile time, delay is accurate to +/- 2us
// plus an overhead of 3 CPU cycles
const float fMHz = (F_CPU/1000000.0);
// subtract two for rounding before dividing by 4
us -= 2;
delay4us:
// delay 4us per loop, less 4 cycles for overhead
_delay_us(4.0 - (4.0 / fMHz));
asm volatile ("sbiw %[us], 4" : [us]"+d"(us));
asm goto( "brpl %l[delay4us]" :::: delay4us);}
SpenceKonde
I have a problem with delayMicroseconds. The sketch below shows two example code lines demonstrating success and the second demonstrating the failure.
void setup() { delay(10000); ookPulse(375, 1125); Serial.setTxBit(PIN3); // https://github.com/SpenceKonde/ATTinyCore/search?q=T84+tx Serial.begin(38400); Serial.println("raw text"); Serial.println(F("F() macro")); Serial.printHex(EEDR); Serial.println(); byte one = 1; Serial.println(one); Serial.println(!one); Serial.println(!!one); } void loop() { // put your main code here, to run repeatedly: if (Serial.available()) { byte c = Serial.read(); delay (60); Serial.print(c, HEX); } } static void ookPulse(int on, int off) {// delayMicroseconds(on + 150); // delayMicroseconds(on + 150); // This will compile delayMicroseconds(off - 200); // This will not compile }
I think the problem is an old one dating back at least to #672 the compiler messages are as follow:
I don't know yet where the source code for delayMicroseconds is located. Any pointers will be greatfully received.