WIP: stm32l4: example for DFSDM irq

examples/stm32/l4/stm32l476rg-nucleo/dfsdm_irq/Makefile

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+##
+## This file is part of the libopencm3 project.
+##
+## This library is free software: you can redistribute it and/or modify
+## it under the terms of the GNU Lesser General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU Lesser General Public License for more details.
+##
+## You should have received a copy of the GNU Lesser General Public License
+## along with this library.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+BINARY=dfsdm_irq
+OBJS = usart_stdio.o syscalls.o
+DEVICE=stm32l476rg
+
+include ../../Makefile.include

examples/stm32/l4/stm32l476rg-nucleo/dfsdm_irq/README.md

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+This demonstrates the DFSDM on the L476RG nucleo board.
+
+* printf via usart1 TX on Pin A9 115200@8n1
+* this example assumes that there is a sigma delta modulator connected to pins B1 (CLK) and C2 (DATA) e.g. TI AMC1306
+* pll configuration from hsi
+* dfsdm0_isr reads the data regularily as soon as they are available.

examples/stm32/l4/stm32l476rg-nucleo/dfsdm_irq/dfsdm_irq.c

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2024 Karl Palsson <[email protected]>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/stm32/exti.h>
+#include <libopencm3/stm32/flash.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/timer.h>
+#include <libopencm3/stm32/usart.h>
+#include <libopencm3/stm32/dma.h>
+
+#include <libopencm3/stm32/l4/dfsdm.h>
+
+#include <stdio.h>
+#include "usart_stdio.h"
+
+#define LED_GREEN_PORT GPIOA
+#define LED_GREEN_PIN GPIO5
+
+/* CPU core clock setup */
+static void clock_setup(void)
+{
+    rcc_clock_setup_pll(&rcc_hsi16_configs[RCC_CLOCK_VRANGE1_80MHZ]);
+}
+
+static void gpio_setup(void)
+{
+    rcc_periph_clock_enable(RCC_GPIOA);
+
+    gpio_mode_setup(LED_GREEN_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_GREEN_PIN);
+}
+
+void dfsdm_filter_setup(void)
+{    
+    dfsdm_flt_set_regular_ch(0, 0);
+    dfsdm_flt_rcont_repeat(0);
+    // dfsdm_flt_rcont_once(0);
+    dfsdm_flt_reg_end_of_conv_irq_enable(0);
+
+    dfsdm_flt_set_sinc_filter_order(0, 3);
+
+    /* (FOSR = FOSR[9:0] +1) same as with clock divider */
+    dfsdm_flt_set_sinc_oversample_ratio(0, 63);
+    dfsdm_flt_set_integrator_oversample_ratio(0, 0);
+
+    /* enable rdma */
+    dfsdm_flt_rdma_enable(0);
+    dfsdm_flt_filter_enable(0);
+
+    printf("DFSDM_FLTxCR1: %lx\r\n", DFSDM_FLTxCR1(0));
+    printf("DFSDM_FLTxCR1: %lx\r\n", DFSDM_FLTxCR2(0));
+}
+
+void dfsdm_setup(void)
+{    
+    /* Setup GPIO pins for AF5 for SPI1 signals. */
+    rcc_periph_clock_enable(RCC_GPIOB);
+    gpio_mode_setup(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO1);
+    gpio_set_af(GPIOB, GPIO_AF6, GPIO1);
+
+    rcc_periph_clock_enable(RCC_GPIOC);
+    gpio_mode_setup(GPIOC, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+    gpio_set_af(GPIOC, GPIO_AF6, GPIO2);
+
+    rcc_periph_clock_enable(RCC_DFSDM);
+
+    dfsdm_set_ckout_src_sys(0);
+
+    /* the actual divider is (Divider = CKOUTDIV+1), so we need to subtract by one: 80MHz/8 would be 10MHz sampling rate */
+    dfsdm_set_ckout_divider(0,7);
+
+    dfsdm_set_datpack_standard(0);
+    dfsdm_set_datmpx_external(0);
+    dfsdm_set_chinsel_same_channel(0);
+    dfsdm_set_ckaben_disable(0);
+    dfsdm_set_scden_disable(0);
+    dfsdm_set_spi_clock_ckout(0);
+    dfsdm_set_sitp_spi_rise_edge(0);
+
+    dfsdm_set_offset(0, 0);
+    dfsdm_set_data_shift(0, 0);
+
+    dfsdm_set_chen_enable(0);
+
+    printf("DFSDM_CHyCFGR1: %lx\r\n", DFSDM_CHyCFGR1(0));
+    printf("DFSDM_CHyCFGR2: %lx\r\n", DFSDM_CHyCFGR2(0));
+}
+
+/*
+ * The rate isr will be called is calculated like this:
+ * fCKIN/(Fosr*(Iosr-1+Ford)+(Ford+1))
+ * Taken from the reference manual STM32L476RG (24.4.13 Data unit block).
+ * So e.g. fCKIN = 10MHz, Fosr = 16, Iosr = 0 (so in this formular I think we should use 1), 
+ * Ford = 3 (Sinc3) this gives:
+ * 10000000/(16*(1-1+3)+(3+1)) = 192307.69230
+ */
+void dfsdm0_isr(void)
+{
+    if(dfsdm_flt_get_eof_regular_conv_flag(0))
+    {
+        int32_t tmp_data = dfsdm_flt_get_regular_ch_conv_data(0);
+
+        /* here you can do something with the converted data */
+        (void) tmp_data;
+
+        gpio_toggle(LED_GREEN_PORT, LED_GREEN_PIN);
+    }
+}
+
+int main(void)
+{
+	clock_setup();
+    gpio_setup();
+    usart_setup();
+
+    printf("Hello from stm32476rg nucleo DFSDM IRQ example!\r\n");
+
+    nvic_enable_irq(NVIC_DFSDM0_IRQ);
+
+    dfsdm_setup();
+    dfsdm_filter_setup();
+    dfsdm_enable(0);
+
+    /* start regular conversion */
+    dfsdm_flt_rswstart(0);
+
+	while (1) 
+    {
+	}
+
+	return 0;
+}

examples/stm32/l4/stm32l476rg-nucleo/dfsdm_irq/syscalls.c

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+/*
+ * newlib_stubs.c
+ *
+ *  Created on: 2 Nov 2010
+ *      Author: nanoage.co.uk
+ *
+ * From "The STM32 discovery Scrapbook":
+ * "Getting Newlib and printf to work with the STM32 and Code Sourcery Lite EABI"
+ * https://sites.google.com/site/stm32discovery/open-source-development-with-the-stm32-discovery/getting-newlib-to-work-with-stm32-and-code-sourcery-lite-eabi
+ *
+ * Note that the read/write function here haven't actually been used. They should probably be revised to use the getchar/putchar
+ * interrupt-based functions defined in usart.c. An example of how to do this is given at http://www.cs.indiana.edu/~geobrown/book.pdf
+ */
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/times.h>
+#include <sys/unistd.h>
+#include <libopencm3/stm32/usart.h>
+
+#undef errno
+extern int errno;
+
+/*
+ environ
+ A pointer to a list of environment variables and their values.
+ For a minimal environment, this empty list is adequate:
+ */
+char *__env[1] = { 0 };
+char **environ = __env;
+
+int _write(int file, char *ptr, int len);
+
+void _exit(int status) {
+	_write(1, "exit", 4);
+	while (1) {
+		;
+	}
+}
+
+int _close(int file) {
+	return -1;
+}
+/*
+ execve
+ Transfer control to a new process. Minimal implementation (for a system without processes):
+ */
+int _execve(char *name, char **argv, char **env) {
+	errno = ENOMEM;
+	return -1;
+}
+/*
+ fork
+ Create a new process. Minimal implementation (for a system without processes):
+ */
+
+int _fork() {
+	errno = EAGAIN;
+	return -1;
+}
+/*
+ fstat
+ Status of an open file. For consistency with other minimal implementations in these examples,
+ all files are regarded as character special devices.
+ The `sys/stat.h' header file required is distributed in the `include' subdirectory for this C library.
+ */
+int _fstat(int file, struct stat *st) {
+	st->st_mode = S_IFCHR;
+	return 0;
+}
+
+/*
+ getpid
+ Process-ID; this is sometimes used to generate strings unlikely to conflict with other processes. Minimal implementation, for a system without processes:
+ */
+
+int _getpid() {
+	return 1;
+}
+
+/*
+ isatty
+ Query whether output stream is a terminal. For consistency with the other minimal implementations,
+ */
+int _isatty(int file) {
+	switch (file) {
+	case STDOUT_FILENO:
+	case STDERR_FILENO:
+	case STDIN_FILENO:
+		return 1;
+	default:
+		//errno = ENOTTY;
+		errno = EBADF;
+		return 0;
+	}
+}
+
+/*
+ kill
+ Send a signal. Minimal implementation:
+ */
+int _kill(int pid, int sig) {
+	errno = EINVAL;
+	return (-1);
+}
+
+/*
+ link
+ Establish a new name for an existing file. Minimal implementation:
+ */
+
+int _link(char *old, char *new) {
+	errno = EMLINK;
+	return -1;
+}
+
+/*
+ lseek
+ Set position in a file. Minimal implementation:
+ */
+int _lseek(int file, int ptr, int dir) {
+	return 0;
+}
+
+/*
+ read
+ Read a character to a file. `libc' subroutines will use this system routine for input from all files, including stdin
+ Returns -1 on error or blocks until the number of characters have been read.
+ */
+
+int _read(int file, char *ptr, int len) {
+    return -1;
+}
+
+/*
+ stat
+ Status of a file (by name). Minimal implementation:
+ int    _EXFUN(stat,( const char *__path, struct stat *__sbuf ));
+ */
+
+int _stat(const char *filepath, struct stat *st) {
+	st->st_mode = S_IFCHR;
+	return 0;
+}
+
+/*
+ times
+ Timing information for current process. Minimal implementation:
+ */
+
+clock_t _times(struct tms *buf) {
+	return -1;
+}
+
+/*
+ unlink
+ Remove a file's directory entry. Minimal implementation:
+ */
+int _unlink(char *name) {
+	errno = ENOENT;
+	return -1;
+}
+
+/*
+ wait
+ Wait for a child process. Minimal implementation:
+ */
+int _wait(int *status) {
+	errno = ECHILD;
+	return -1;
+}
+
+/*
+ * Called by libc stdio fwrite functions
+ */
+int
+_write(int fd, char *ptr, int len)
+{
+	int i = 0;
+
+	/*
+	 * Write "len" of char from "ptr" to file id "fd"
+	 * Return number of char written.
+	 *
+	 * Only work for STDOUT, STDIN, and STDERR
+	 */
+	if (fd > 2) {
+		return -1;
+	}
+	while (*ptr && (i < len)) {
+		usart_send_blocking(USART1, *ptr);
+		if (*ptr == '\n') {
+			usart_send_blocking(USART1, '\r');
+		}
+		i++;
+		ptr++;
+	}
+	return i;
+}