/** * Copyright (c) 2020 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause */ #include <stdio.h> #include "pico/stdlib.h" #include "hardware/pll.h" #include "hardware/clocks.h" #include "hardware/structs/pll.h" #include "hardware/structs/clocks.h" void measure_freqs(void) { uint f_pll_sys = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_PLL_SYS_CLKSRC_PRIMARY); uint f_pll_usb = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_PLL_USB_CLKSRC_PRIMARY); uint f_rosc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_ROSC_CLKSRC); uint f_clk_sys = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_SYS); uint f_clk_peri = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_PERI); uint f_clk_usb = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_USB); uint f_clk_adc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_ADC); #ifdef CLOCKS_FC0_SRC_VALUE_CLK_RTC uint f_clk_rtc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_RTC); #endif printf("pll_sys = %dkHz\n", f_pll_sys); printf("pll_usb = %dkHz\n", f_pll_usb); printf("rosc = %dkHz\n", f_rosc); printf("clk_sys = %dkHz\n", f_clk_sys); printf("clk_peri = %dkHz\n", f_clk_peri); printf("clk_usb = %dkHz\n", f_clk_usb); printf("clk_adc = %dkHz\n", f_clk_adc); #ifdef CLOCKS_FC0_SRC_VALUE_CLK_RTC printf("clk_rtc = %dkHz\n", f_clk_rtc); #endif // Can't measure clk_ref / xosc as it is the ref } int main() { stdio_init_all(); printf("Hello, world!\n"); measure_freqs(); // Change clk_sys to be 48MHz. The simplest way is to take this from PLL_USB // which has a source frequency of 48MHz clock_configure(clk_sys, CLOCKS_CLK_SYS_CTRL_SRC_VALUE_CLKSRC_CLK_SYS_AUX, CLOCKS_CLK_SYS_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB, 48 * MHZ, 48 * MHZ); // Turn off PLL sys for good measure pll_deinit(pll_sys); // CLK peri is clocked from clk_sys so need to change clk_peri's freq clock_configure(clk_peri, 0, CLOCKS_CLK_PERI_CTRL_AUXSRC_VALUE_CLK_SYS, 48 * MHZ, 48 * MHZ); // Re init uart now that clk_peri has changed stdio_init_all(); measure_freqs(); printf("Hello, 48MHz"); return 0; }

This firmware image was imported from the pico-examples repository. 


Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
   disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.