Sending a clock signal to GPIO from 32u4.

[VelvetLounger]

Is it possible to send an 8 or 16 MHz clock signal to one of the GPIO? I have a device that needs either its own oscillator connected to OSC1 and OSC2. Or it will accept a clock signal from an external clock into OSC1. My thought is that is a simpler solution than putting more components onto my board. I just don't know if it can be done or how.

If anyone can point me in a good direction I would appreciate it.

Thanks!

[mikeysklar]

You should be able to use a timer to generate a 8MHz signal on your 32u4. Here is an example using timer4. 16MHz is not going to be an option with a 32u4 running at 8MHz.

https://electronics.stackexchange.com/q ... ing-timer4

Code: Select all

// reset timer4
OCR4C = 0;
OCR4D = 0;

TCCR4A = 0x00;
TCCR4B = 0x00;
TCCR4C = 0x00;
TCCR4D = 0x00;

TCNT4=0;

// Toggle OC4D on Compare Match | enable PWM
TCCR4C = _BV(COM4D0) | _BV(PWM4D);


// Clear Timer on Compare Match
TCCR4D = _BV(WGM41);

// set lock bit for sync update
TCCR4E = _BV(TLOCK4);

// Set compare value
OCR4C = CLOCKCYCLE*2;
OCR4D = CLOCKCYCLE;

// No prescaling
TCCR4B = _BV(CS10);

[sj_remington]

If the CKOUT fuse is programmed, the system clock (typically 16 MHz with Arduino) will appear on PORTC, pin 7.

[VelvetLounger]

You should be able to use a timer to generate a 8MHz signal on your 32u4. Here is an example using timer4. 16MHz is not going to be an option with a 32u4 running at 8MHz.

Hi mikeysklar. I'm using the 5V Itsy Bitsy which runs at 16 MHz so maybe I can make it work. However according the the datasheet for the MCP2515 it can run with 4,8, or 16MHz. Thank you for the link and the code.

[VelvetLounger]

If the CKOUT fuse is programmed, the system clock (typically 16 MHz with Arduino) will appear on PORTC, pin 7.

Hi sj_remington. I will look into setting the CKOUT fuse.

Thank you very much