105 lines
3.8 KiB
C
105 lines
3.8 KiB
C
/*
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "pico/stdlib.h"
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#include "hardware/pll.h"
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#include "hardware/clocks.h"
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#if PICO_STDIO_UART
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#include "pico/stdio_uart.h"
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#else
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#include "pico/binary_info.h"
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#endif
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// everything running off the USB oscillator
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void set_sys_clock_48mhz() {
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if (!running_on_fpga()) {
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// Change clk_sys to be 48MHz. The simplest way is to take this from PLL_USB
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// which has a source frequency of 48MHz
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clock_configure(clk_sys,
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CLOCKS_CLK_SYS_CTRL_SRC_VALUE_CLKSRC_CLK_SYS_AUX,
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CLOCKS_CLK_SYS_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB,
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48 * MHZ,
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48 * MHZ);
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// Turn off PLL sys for good measure
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pll_deinit(pll_sys);
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// CLK peri is clocked from clk_sys so need to change clk_peri's freq
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clock_configure(clk_peri,
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0,
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CLOCKS_CLK_PERI_CTRL_AUXSRC_VALUE_CLK_SYS,
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48 * MHZ,
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48 * MHZ);
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}
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}
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void set_sys_clock_pll(uint32_t vco_freq, uint post_div1, uint post_div2) {
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if (!running_on_fpga()) {
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clock_configure(clk_sys,
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CLOCKS_CLK_SYS_CTRL_SRC_VALUE_CLKSRC_CLK_SYS_AUX,
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CLOCKS_CLK_SYS_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB,
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48 * MHZ,
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48 * MHZ);
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pll_init(pll_sys, 1, vco_freq, post_div1, post_div2);
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uint32_t freq = vco_freq / (post_div1 * post_div2);
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// Configure clocks
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// CLK_REF = XOSC (12MHz) / 1 = 12MHz
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clock_configure(clk_ref,
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CLOCKS_CLK_REF_CTRL_SRC_VALUE_XOSC_CLKSRC,
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0, // No aux mux
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12 * MHZ,
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12 * MHZ);
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// CLK SYS = PLL SYS (125MHz) / 1 = 125MHz
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clock_configure(clk_sys,
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CLOCKS_CLK_SYS_CTRL_SRC_VALUE_CLKSRC_CLK_SYS_AUX,
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CLOCKS_CLK_SYS_CTRL_AUXSRC_VALUE_CLKSRC_PLL_SYS,
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freq, freq);
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clock_configure(clk_peri,
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0, // Only AUX mux on ADC
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CLOCKS_CLK_PERI_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB,
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48 * MHZ,
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48 * MHZ);
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}
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}
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bool check_sys_clock_khz(uint32_t freq_khz, uint *vco_out, uint *postdiv1_out, uint *postdiv_out) {
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uint crystal_freq_khz = clock_get_hz(clk_ref) / 1000;
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for (uint fbdiv = 320; fbdiv >= 16; fbdiv--) {
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uint vco = fbdiv * crystal_freq_khz;
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if (vco < 400000 || vco > 1600000) continue;
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for (uint postdiv1 = 7; postdiv1 >= 1; postdiv1--) {
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for (uint postdiv2 = postdiv1; postdiv2 >= 1; postdiv2--) {
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uint out = vco / (postdiv1 * postdiv2);
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if (out == freq_khz && !(vco % (postdiv1 * postdiv2))) {
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*vco_out = vco * 1000;
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*postdiv1_out = postdiv1;
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*postdiv_out = postdiv2;
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return true;
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}
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}
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}
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}
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return false;
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}
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void setup_default_uart() {
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#if PICO_STDIO_UART
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stdio_uart_init();
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#elif defined(PICO_DEFAULT_UART_BAUD_RATE) && defined(PICO_DEFAULT_UART_TX_PIN) && defined(PICO_DEFAULT_UART_RX_PIN)
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// this is mostly for backwards compatibility - stdio_uart_init is a bit more nuanced, and usually likely to be present
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uart_init(uart_default, PICO_DEFAULT_UART_BAUD_RATE);
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if (PICO_DEFAULT_UART_TX_PIN >= 0)
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gpio_set_function(PICO_DEFAULT_UART_TX_PIN, GPIO_FUNC_UART);
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if (PICO_DEFAULT_UART_RX_PIN >= 0)
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gpio_set_function(PICO_DEFAULT_UART_RX_PIN, GPIO_FUNC_UART);
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bi_decl_if_func_used(bi_2pins_with_func(PICO_DEFAULT_UART_RX_PIN, PICO_DEFAULT_UART_TX_PIN, GPIO_FUNC_UART));
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#endif
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}
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