ESP8266 Community Forum

- Wed Nov 02, 2016 9:42 am #57549 I have ESP01 version with 26MHz crystal on the board. Also SPI flash chip with 1MB memory with preloaded AT firmware. All works well, but I don't understand something. When bootload writes output to the serial it writes that SPI is running on 40MHz. What am I missing here?? This is not correct.

Thank you for the explanation

- Thu Nov 03, 2016 8:04 am #57595 The 26MHz external oscillator provides clock to an internal PLL to generate 80MHz to CPU and all peripherals.
Then, the SPI clock divider, which can be set at different clock divide multiples is defaulted to CPU/2, which therefore is 40MHz. Setting it to CPU/4 would therefore be 20MHz, CPU/8 would be 10MHz, and so forth.