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dda
dda
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It Is the shiftOut code depending on the (low) speed of an Arduino?

In the (official) file wiring_shift.cwiring_shift.c I found the following code for shiftOut:

void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
{
    uint8_t i;

    for (i = 0; i < 8; i++)  {
        if (bitOrder == LSBFIRST)
            digitalWrite(dataPin, !!(val & (1 << i)));
        else    
            digitalWrite(dataPin, !!(val & (1 << (7 - i))));
            
        digitalWrite(clockPin, HIGH);
        digitalWrite(clockPin, LOW);        
    }
}

However, the last two digitalWritedigitalWrite commands occur directly after each other. I I wouldn't hope that the digitalWritedigitalWrite depends on some time or delay, so how it can it be assuedassumed that the slave device sees the clockPin is HIGH if the Arduino immediately sets the clockPin to LOW again?

(My plan is to convert the shiftIn/shiftOut code to STM32 using HAL/CubeIDE).

It the shiftOut code depending on the (low) speed of an Arduino?

In the (official) file wiring_shift.c I found the following code for shiftOut:

void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
{
    uint8_t i;

    for (i = 0; i < 8; i++)  {
        if (bitOrder == LSBFIRST)
            digitalWrite(dataPin, !!(val & (1 << i)));
        else    
            digitalWrite(dataPin, !!(val & (1 << (7 - i))));
            
        digitalWrite(clockPin, HIGH);
        digitalWrite(clockPin, LOW);        
    }
}

However, the last two digitalWrite commands occur directly after each other. I wouldn't hope that the digitalWrite depends on some time or delay, so how it can be assued that the slave device sees the clockPin is HIGH if the Arduino immediately sets the clockPin to LOW again?

(My plan is to convert the shiftIn/shiftOut code to STM32 using HAL/CubeIDE).

Is the shiftOut code depending on the (low) speed of an Arduino?

In the (official) file wiring_shift.c I found the following code for shiftOut:

void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
{
    uint8_t i;

    for (i = 0; i < 8; i++)  {
        if (bitOrder == LSBFIRST)
            digitalWrite(dataPin, !!(val & (1 << i)));
        else    
            digitalWrite(dataPin, !!(val & (1 << (7 - i))));
            
        digitalWrite(clockPin, HIGH);
        digitalWrite(clockPin, LOW);        
    }
}

However, the last two digitalWrite commands occur directly after each other. I wouldn't hope that digitalWrite depends on some time or delay, so how can it be assumed that the slave device sees the clockPin is HIGH if the Arduino immediately sets the clockPin to LOW again?

(My plan is to convert the shiftIn/shiftOut code to STM32 using HAL/CubeIDE).

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Michel Keijzers
Michel Keijzers
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  • 59

It the shiftOut code depending on the (low) speed of an Arduino?

In the (official) file wiring_shift.c I found the following code for shiftOut:

void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
{
    uint8_t i;

    for (i = 0; i < 8; i++)  {
        if (bitOrder == LSBFIRST)
            digitalWrite(dataPin, !!(val & (1 << i)));
        else    
            digitalWrite(dataPin, !!(val & (1 << (7 - i))));
            
        digitalWrite(clockPin, HIGH);
        digitalWrite(clockPin, LOW);        
    }
}

However, the last two digitalWrite commands occur directly after each other. I wouldn't hope that the digitalWrite depends on some time or delay, so how it can be assued that the slave device sees the clockPin is HIGH if the Arduino immediately sets the clockPin to LOW again?

(My plan is to convert the shiftIn/shiftOut code to STM32 using HAL/CubeIDE).