Teensy 4.1 Serial Ports and GPIO

[bdoan]

I am not clear on how Arduino code works with the "shiftout" function.

I need to shift out 12 bits.

should I use the shiftout or just bitbang with other functions?

void WriteToDAC(void)
{
//#define DAC_CLK     28
//#define DAC_Data    29
//#define VddDAC_Sel  30

byte bitcount;
int  DACvalue;
if (DACbuffer > 4095)         // tens, ones, tenths
   DACbuffer = 0;             // limit to f.s. of DAC 5V   
DACvalue = DACbuffer * 16;   // Move 12 bit to MSB position for 16bit (long)         
output_low(VddDAC_Sel);
for (bitcount=12; bitcount>0;bitcount--)
   {
   shiftOut(DAC_Data,DAC_CLK,MSBFIRST,DACbuffer[bitcount]);  ??????????????
   //Output_High(DAC_CLK);     ??????????????
   //delay(1);                             ??????????????
   //Output_Low(DAC_CLK);      ??????????????
   }
output_high(VddDAC_Sel);
}

 

[PaulStoffregen]

shiftOut() transmits a byte (8 bits).

Documentation here:

shiftOut() - Arduino Reference

The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords.

www.arduino.cc

For 12 bits, just write your own loop using digitalWriteFast() and delayNanoseconds() or delayMicroseconds().

 

[bdoan]

shiftOut() transmits a byte (8 bits).

Documentation here:

shiftOut() - Arduino Reference

The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords.

www.arduino.cc

For 12 bits, just write your own loop using digitalWriteFast() and delayNanoseconds() or delayMicroseconds().

Thanks.

Shift and test bit?
Or just AND with a mask to get the bit value?

 

[MarkT]

Why not look at the source code of shiftOut and copy it with adaptations?

 

[bdoan]

I found code