Boot speed 52MHz not 80?

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Boot speed 52MHz not 80?

By cnlohr
- Fri Oct 07, 2016 2:57 pm #56202 I am running in a really odd problem. When I compile for use without any SDK, my code seems to execute at 52 MHz, not 80 MHz. This is reflected both in the ets_delay_us and in the baud rate divisor. What has to be done to switch the ESP to 80 MHz after boot?

(This is needed to make the USB bootloader work)
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Re: Boot speed 52MHz not 80?

By cnlohr
- Fri Oct 07, 2016 4:28 pm #56207 Never mind. Igrr explained it.

When bootloader runs, PLL is not enabled yet, this is done in one of closed source libraries. I would have expected to see 26 MHz frequency, but maybe there is an option to use 2*XTAL... I will check.


For loaded programs — not really, as SDK startup code resets frequency to 80MHz. For the USB stack I can imagine switching from 80 to 52 can be a lot of work... I will see if I can pull some bits from closed source libs to enable 80MHz at boot.
Because this is not necessary for normal (non-USB) boot, I want to check if cable is connected first. If it is, I will load the rest of USB code and libphy into RAM, set frequency, and then initialize USB.


That part of the 8266 is not publicly documented, so I can't give you any pointers.

I'm on vacation now, back to office next week; will look up those 10 lines of code with are needed to switch frequency. Then I'll make a branch of Arduino with 80Mhz enabled in bootloader, so that you can try running esp-usb there.
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Re: Boot speed 52MHz not 80?

By cnlohr
- Fri Oct 07, 2016 10:04 pm #56218 pvxx had the solution...

Code: Select all    if(rom_i2c_readReg(103,4,1) != 136) { // 8: 40MHz, 136: 26MHz
        //if(get_sys_const(sys_const_crystal_26m_en) == 1) { // soc_param0: 0: 40MHz, 1: 26MHz, 2: 24MHz
            // set 80MHz PLL CPU
            rom_i2c_writeReg(103,4,1,136);
            rom_i2c_writeReg(103,4,2,145);
        //}
    }
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Re: Boot speed 52MHz not 80?

By RichardS
- Fri Oct 07, 2016 10:36 pm #56220 Nice work I saw the non-SDK 2.5K loader! Exciting....

RichardS
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