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authorDaniel Serpell2012-08-22 00:05:10 -0400
committerNicolas Schodet2012-09-27 23:12:18 +0200
commitaac5909ff133a71dc01037712f86e89f4e7877d7 (patch)
treecbf332bebca781a263aa62ca2b92ce33b2a2a8d1
parente4819d3cd284e76339887a45598269dbe1479da7 (diff)
Add a floating-point example to the stm32f4.
This example calculates a mandelbrot fractal using floating point in C.
-rw-r--r--examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile25
-rw-r--r--examples/stm32/f4/stm32f4-discovery/mandelbrot/README12
-rw-r--r--examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c127
3 files changed, 164 insertions, 0 deletions
diff --git a/examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile b/examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile
new file mode 100644
index 0000000..3879eca
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile
@@ -0,0 +1,25 @@
+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## 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 = mandel
+
+LDSCRIPT = ../stm32f4-discovery.ld
+
+include ../../Makefile.include
+
diff --git a/examples/stm32/f4/stm32f4-discovery/mandelbrot/README b/examples/stm32/f4/stm32f4-discovery/mandelbrot/README
new file mode 100644
index 0000000..fe4fb13
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/mandelbrot/README
@@ -0,0 +1,12 @@
+------------------------------------------------------------------------------
+README
+------------------------------------------------------------------------------
+
+This example program demonstrates the floating point coprocessor usage on
+the ST STM32F4DISCOVERY eval board.
+
+A mandelbrot fractal is calculated and sent as "ascii-art" image through
+the USART2.
+
+The terminal settings for the receiving device/PC are 38400 8n1.
+
diff --git a/examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c b/examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c
new file mode 100644
index 0000000..5cbdafd
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c
@@ -0,0 +1,127 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ * Copyright (C) 2012 Daniel Serpell <daniel.serpell@gmail.com>
+ *
+ * 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 <libopencm3/stm32/f4/rcc.h>
+#include <libopencm3/stm32/f4/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+void clock_setup(void)
+{
+ /* Enable high-speed clock at 120MHz */
+ rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_120MHZ]);
+
+ /* Enable GPIOD clock for LED & USARTs. */
+ rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
+ rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPAEN);
+
+ /* Enable clocks for USART2. */
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
+}
+
+void usart_setup(void)
+{
+ /* Setup USART2 parameters. */
+ usart_set_baudrate(USART2, 38400);
+ usart_set_databits(USART2, 8);
+ usart_set_stopbits(USART2, USART_STOPBITS_1);
+ usart_set_mode(USART2, USART_MODE_TX);
+ usart_set_parity(USART2, USART_PARITY_NONE);
+ usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+
+ /* Finally enable the USART. */
+ usart_enable(USART2);
+}
+
+void gpio_setup(void)
+{
+ /* Setup GPIO pin GPIO12 on GPIO port D for LED. */
+ gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO12);
+
+ /* Setup GPIO pins for USART2 transmit. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+
+ /* Setup USART2 TX pin as alternate function. */
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+}
+
+/* Maximum number of iterations for the escape-time calculation */
+#define maxIter 32
+/* This array converts the iteration count to a character representation. */
+static char color[maxIter+1] = " .:++xxXXX%%%%%%################";
+
+/* Main mandelbrot calculation */
+static int iterate(float px, float py)
+{
+ int it=0;
+ float x=0,y=0;
+ while(it<maxIter)
+ {
+ float nx = x*x;
+ float ny = y*y;
+ if( (nx + ny) > 4 )
+ return it;
+ // Zn+1 = Zn^2 + P
+ y = 2*x*y + py;
+ x = nx - ny + px;
+ it++;
+ }
+ return 0;
+}
+
+static void mandel(float cX, float cY, float scale)
+{
+ int x,y;
+ for(x=-60;x<60;x++)
+ {
+ for(y=-50;y<50;y++)
+ {
+ int i = iterate(cX+x*scale, cY+y*scale);
+ usart_send_blocking(USART2, color[i]);
+ }
+ usart_send_blocking(USART2, '\r');
+ usart_send_blocking(USART2, '\n');
+ }
+}
+
+int main(void)
+{
+ float scale = 0.25f, centerX = -0.5f, centerY = 0.0f;
+
+ clock_setup();
+ gpio_setup();
+ usart_setup();
+
+ while (1) {
+ /* Blink the LED (PD12) on the board with each fractal drawn. */
+ gpio_toggle(GPIOD, GPIO12); /* LED on/off */
+ mandel(centerX,centerY,scale); /* draw mandelbrot */
+
+ /* Change scale and center */
+ centerX += 0.175f * scale;
+ centerY += 0.522f * scale;
+ scale *= 0.875f;
+
+ usart_send_blocking(USART2, '\r');
+ usart_send_blocking(USART2, '\n');
+ }
+
+ return 0;
+}