blackmagic/examples/other/dma_mem2mem/dma.c

/*
 * This file is part of the libopenstm32 project.
 *
 * Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopenstm32/rcc.h>
#include <libopenstm32/flash.h>
#include <libopenstm32/gpio.h>
#include <libopenstm32/usart.h>
#include <libopenstm32/dma.h>

/* Set STM32 to 72 MHz. HSE 16MHz */
void clock_setup(void)
{
        /* enable Internal High Speed Oscillator */
        rcc_osc_on(HSI);
        rcc_wait_for_osc_ready(HSI);

        /* Select HSI as SYSCLK source. */
        rcc_set_sysclk_source(SW_SYSCLKSEL_HSICLK);

        /* enable External High Speed Oscillator 16MHz */
        rcc_osc_on(HSE);
        rcc_wait_for_osc_ready(HSE);
        rcc_set_sysclk_source(SW_SYSCLKSEL_HSECLK);

        /* set prescalers for ADC, ABP1, ABP2...  make this before touching the PLL */
        rcc_set_hpre(HPRE_SYSCLK_NODIV); //prescales the AHB clock from the SYSCLK
        rcc_set_adcpre(ADCPRE_PLCK2_DIV6); //prescales the ADC from the APB2 clock; max 14MHz
        rcc_set_ppre1(PPRE1_HCLK_DIV2); //prescales the APB1 from the AHB clock; max 36MHz
        rcc_set_ppre2(PPRE2_HCLK_NODIV); //prescales the APB2 from the AHB clock; max 72MHz

        /* sysclk should run with 72MHz -> 2 Waitstates ; choose 0WS from 0-24MHz, 1WS from 24-48MHz, 2WS from 48-72MHz */
        flash_set_ws(FLASH_LATENCY_2WS);

        /* Set the PLL multiplication factor to 9. -> 16MHz (external) * 9 (multiplier) / 2 (PLLXTPRE_HSE_CLK_DIV2) = 72MHz */
        rcc_set_pll_multiplication_factor(PLLMUL_PLL_CLK_MUL9);

        /* Select HSI as PLL source. */
        rcc_set_pll_source(PLLSRC_HSE_CLK);

        /* divide external frequency by 2 before entering pll (only valid/needed for HSE) */
        rcc_set_pllxtpre(PLLXTPRE_HSE_CLK_DIV2);

        /* Enable PLL oscillator and wait for it to stabilize. */
        rcc_osc_on(PLL);
        rcc_wait_for_osc_ready(PLL);

        /* Select PLL as SYSCLK source. */
        rcc_set_sysclk_source(SW_SYSCLKSEL_PLLCLK);
}

void usart_setup(void)
{
	/* Enable clocks for GPIO port A (for GPIO_USART1_TX) and USART1. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, IOPAEN);
	rcc_peripheral_enable_clock(&RCC_APB2ENR, USART1EN);

	/* Setup GPIO pin GPIO_USART1_TX/GPIO9 on GPIO port A for transmit. */
	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
	              GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);

	/* Setup UART parameters. */
	usart_set_baudrate(USART1, 115200);
	usart_set_databits(USART1, 8);
	usart_set_stopbits(USART1, USART_STOPBITS_1);
	usart_set_mode(USART1, USART_MODE_TX_RX);
	usart_set_parity(USART1, USART_PARITY_NONE);
	usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);

	/* Finally enable the USART. */
	usart_enable(USART1);
}

void gpio_setup(void)
{
	/* Enable GPIOB clock. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, IOPBEN);

	/* Set GPIO6/7 (in GPIO port B) to 'output push-pull' for the LEDs. */
	gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ,
	              GPIO_CNF_OUTPUT_PUSHPULL, GPIO6);
	gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ,
	              GPIO_CNF_OUTPUT_PUSHPULL, GPIO7);
}

void my_usart_print_string(u32 usart, char * s)
{
	while (*s != 0) {
		usart_send(usart, *s);
		s++;
	}
}

int main(void)
{
	/* Exactly 20 bytes including '0' at the end.
	   We want to transfer 32bit * 5 so it should fit */
	char s1[20] = "Hello STM MEM2MEM\r\n";
	char s2[20];
	
	clock_setup();
	gpio_setup();
	usart_setup();

	gpio_clear(GPIOB, GPIO7);	/* LED1 on */
	gpio_set(GPIOB, GPIO6);		/* LED2 off */
	
	my_usart_print_string(USART1, "s1 ");
	my_usart_print_string(USART1, s1);

	rcc_peripheral_enable_clock(&RCC_AHBENR, DMA1EN);

	/* MEM2MEM mode for channel 1. */	
	dma_enable_mem2mem_mode(DMA1, DMA_CHANNEL1);

	/* Highest priority. */
	dma_set_priority(DMA1, DMA_CHANNEL1, DMA_CCR1_PL_VERY_HIGH);

	/* 32Bit wide transfer for source and destination. */
	dma_set_memory_size(DMA1, DMA_CHANNEL1, DMA_CCR1_MSIZE_32BIT);
	dma_set_peripheral_size(DMA1, DMA_CHANNEL1, DMA_CCR1_PSIZE_32BIT);

	/* After each 32Bit we have to increase the addres because we use RAM. */
	dma_enable_memory_increment_mode(DMA1, DMA_CHANNEL1);
	dma_enable_peripheral_increment_mode(DMA1, DMA_CHANNEL1);

	/* We define the source as peripheral. */
	dma_set_read_from_peripheral(DMA1, DMA_CHANNEL1);

	/* We want to transfer string s1. */
	dma_set_peripheral_address(DMA1, DMA_CHANNEL1, (u32) &s1);

	/* Destination should be string s2. */
	dma_set_memory_address(DMA1, DMA_CHANNEL1, (u32) &s2);

	/* Set number of DATA to transfer.
	   Remember that this means not necessary bytes but MSIZE or PSIZE
	   depending from your source device. */
	dma_set_number_of_data(DMA1, DMA_CHANNEL1, 5); 

	/* Start DMA transfer. */	
	dma_enable_channel(DMA1, DMA_CHANNEL1);

	/* TODO: write a function to get the interrupt flags. */
	while(!(DMA_ISR(DMA1) & 0x0000001))
	{
	}

	dma_disable_channel(DMA1, DMA_CHANNEL1);

	/* String s1 should now already be transferred to s2. */	
	my_usart_print_string(USART1, "s2 ");
	my_usart_print_string(USART1, s2);

	gpio_clear(GPIOB, GPIO6);	/* LED2 on */
	while(1); /* Halt. */

	return 0;
}