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Add a floating-point example to the stm32f4.

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This example calculates a mandelbrot fractal using floating point
in C.
This commit is contained in:
Daniel Serpell 2012-08-22 00:05:10 -04:00 committed by Nicolas Schodet
parent e4819d3cd2
commit aac5909ff1
3 changed files with 164 additions and 0 deletions
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25
examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile Normal file
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##
## 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

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examples/stm32/f4/stm32f4-discovery/mandelbrot/README Normal file
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------------------------------------------------------------------------------
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.

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examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c Normal file
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/*
* 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;
}