ChuckM

/*                                                                                                  
 * Look at using the i2c functions in the utility library                                                   
 *                                                                                                  
 * Copyright (c) 2015, Chuck McManis, all rights reserved.                                          
 *                                                                                                  
 * This example talks to the XY screen touch controller
 * (its a peripheral already on the board) and prints
 * the co-ordinates pressed on the serial port.
 */

ChuckM

void
update_cursor(int cursor_num)
{
    struct cursor_data_struct *cursor;
    uint32_t timer;
    int x, y;
    int16_t delta;
    int c_limit;
    int16_t cur;

ChuckM

/*
 * Very simple blink function which will
 * blink an LED on the Nucleo board.
 */

#include <stdint.h>
#include <loc3util/stm32/pins.h>
#include <loc3util/stm32/clock.h>

ChuckM

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/cm3/systick.h>
#include <libopencm3/cm3/sync.h>

#include <local_libs/util_timer.h>

#include <local_conf/board_conf.h>

ChuckM

#!/usr/bin/env perl
#
# This is me doodling around with the various restrictions on PLL
# values in the STM32F Series Cortex-M chips to find the "best"
# settings for someone using the internal 16Mhz clock. Not sure
# why you would use one over the other exactly.
#
# According to the spec, the closer the "input" frequency to the
# PLL is to 2Mhz the less jitter it has, with an HSI of 16Mhz
# and PLLM set to /8 you get exactly 2Mhz, but you can go all

ChuckM

/* makes capturing the output with a logic analyzer easier */
#define FLAG_ON gpio_set(GPIOC, GPIO2)
#define FLAG_OFF gpio_clear(GPIOC, GPIO2)

/*
 * This then sets up the SPI2 port
 */
void
spi_test(void) {
    rcc_periph_clock_enable(RCC_SPI1);

ChuckM

void
callback(void) {
    ... do what you need to do ...;
}

void notify_on_true(uint32_t gpio_bit, (void ()) *callme) {
      if (read_gpio() & gpio_bit) != 0) {
           *callme();
      }

ChuckM

struct debug_data {
   char *data;
   struct debug_data *nxt;
}

struct debug_data *root; // all of the debug chunks

...
...
new_debug_data(char *dbg_string) {

ChuckM

Overview

Setting up the clock tree is fundamental for the Cortex M family but it isn't an often used capability. Generally these functions are called once in a piece of startup code and then forgotten. In the ST Micro family of Cortex-M processors, support for their clock trees has varied from family to family, both in name and in features. This proposal is to unify that support around some key API calls that would be available on all members of the family.

RCC Setup

Generally there are a small number of clocks that can be used as the system clock for the ST Micro processors, these usually include a default "High Speed" internal (HSI) RC oscillator, a high speed, externally supplied, clock (HSE), and a PLL which is primed by either HSI or HSE and provides a system clock frequency that is different than the input frequency. The Lx family has added a medium speed internal clock (MSI) to this mix.

This proposal suggests that setup of all these clocks should be done in a function named: `rcc_XXX_

ChuckM

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
    
void setup_clock(void) {
   rcc_clock_setup_in_hsi_out_48mhz();
}
    
void setup_gpio(void) {
   gpio_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUSHPULL_NONE, GPIO5);
}