ESP8266 Community Forum

Yes, @lethe is right, you can not use SPI SCLK for continous clock.
You should probably use the CLK_XTAL available on GPIO3 but you will loose the UART RX.
It will provide a 26MHz clock, so you will also need a divider by 8 to get frequency at 3.25MHz.

Loosing the UART RX might actually not even be a problem. I will give it a try tomorrow.
Thank you for your help.

If you can get away with wiring it over from another pin, you can get a 26MHz output if you set pin0 to function4. With that you can use a counter chip to divide it down to what you need.

Another option is to either use the I2S0_BCK which can be output on pin 13 or 15 (I haven't been able to remap this).

The only way that may be able to pass the clock onto the right pin is it may be possible to use I2S0_WS by telling the I2S peripheral to use the smallest divider setting which should get you 1.25MHz. I haven't been able to get this way to work yet though as I can't seem to enable WS or remap it over to the right pin.

Hope this is helpful.

Hi Martin and all,

I can able to generate the CLK_OUT frequency but kindly let me know how to prescale it to 12MHz in arduino.

Also please confirm the output frequency is sure 26MHz.