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-rw-r--r--examples/lm4f/stellaris-ek-lm4f120xl/miniblink/README21
-rw-r--r--examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c193
-rw-r--r--examples/stm32/f4/stm32f4-discovery/usart_irq/Makefile25
-rw-r--r--examples/stm32/f4/stm32f4-discovery/usart_irq/README14
-rw-r--r--examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c115
5 files changed, 331 insertions, 37 deletions
diff --git a/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/README b/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/README
index f6441be..a19550d 100644
--- a/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/README
+++ b/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/README
@@ -2,8 +2,21 @@
README
------------------------------------------------------------------------------
-Flashes the Red, Green and Blue diodes on the board, in order.
-RED controlled by PF1
-Green controlled by PF3
-Blue controlled by PF2
+This example demonstrates the following:
+ * Configuriong GPIO pins
+ * Toggling GPIO pins
+ * Setting up and using GPIO interrupts
+ * Unlocking protected GPIO pins
+ * Controlling the system clock
+ * Changing the system clock on the fly
+
+Flashes the Red, Green and Blue diodes on the board, in order. The system clock
+starts at 80MHz.
+Pressing SW2 toggles the system clock between 80MHz, 57MHz, 40MHz ,20MHz, and
+16MHz by changing the PLL divisor.
+Pressing SW1 bypasses the PLL completely, and runs off the raw 16MHz clock
+provided by the external crystal oscillator.
+The LEDs will toggle at different speeds, depending on the system clock. The
+system clock changes are handled within the interrupt service routine.
+
diff --git a/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c b/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c
index 0231a90..d03be0c 100644
--- a/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c
+++ b/examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c
@@ -2,7 +2,7 @@
* This file is part of the libopencm3 project.
*
* Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
- * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ * Copyright (C) 2012-2013 Alexandru Gagniuc <mr.nuke.me@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
@@ -27,66 +27,193 @@
* Green controlled by PF3
* Blue controlled by PF2
*/
+#include <libopencm3/cm3/nvic.h>
#include <libopencm3/lm4f/systemcontrol.h>
+#include <libopencm3/lm4f/rcc.h>
#include <libopencm3/lm4f/gpio.h>
+#include <libopencm3/lm4f/nvic.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+
+/* This is how the RGB LED is connected on the stellaris launchpad */
+#define RGB_PORT GPIOF
+enum {
+ LED_R = GPIO1,
+ LED_G = GPIO3,
+ LED_B = GPIO2,
+};
+
+/* This is how the user switches are connected to GPIOF */
+enum {
+ USR_SW1 = GPIO4,
+ USR_SW2 = GPIO0,
+};
+
+/* The divisors we loop through when the user presses SW2 */
+enum {
+ PLL_DIV_80MHZ = 5,
+ PLL_DIV_57MHZ = 7,
+ PLL_DIV_40MHZ = 10,
+ PLL_DIV_20MHZ = 20,
+ PLL_DIV_16MHZ = 25,
+};
+
+static const u8 plldiv[] = {
+ PLL_DIV_80MHZ,
+ PLL_DIV_57MHZ,
+ PLL_DIV_40MHZ,
+ PLL_DIV_20MHZ,
+ PLL_DIV_16MHZ,
+ 0
+};
+/* The PLL divisor we are currently on */
+static size_t ipll = 0;
+/* Are we bypassing the PLL, or not? */
+static bool bypass = false;
-void gpio_setup(void)
+/*
+ * Clock setup:
+ * Take the main crystal oscillator at 16MHz, run it through the PLL, and divide
+ * the 400MHz PLL clock to get a system clock of 80MHz.
+ */
+static void clock_setup(void)
+{
+ rcc_sysclk_config(OSCSRC_MOSC, XTAL_16M, PLL_DIV_80MHZ);
+}
+
+/*
+ * GPIO setup:
+ * Enable the pins driving the RGB LED as outputs.
+ */
+static void gpio_setup(void)
{
- SYSCTL_RCGCGPIO |= 0x20; /* Enable GPIOF in run mode. */
- const u32 outpins = ((1<<3) | (1<<2) | (1<<1));
+ /*
+ * Configure GPIOF
+ * This port is used to control the RGB LED
+ */
+ periph_clock_enable(RCC_GPIOF);
+ const u32 outpins = (LED_R | LED_G | LED_B);
+
+ GPIO_DIR(RGB_PORT) |= outpins; /* Configure outputs. */
+ GPIO_DEN(RGB_PORT) |= outpins; /* Enable digital function on outputs. */
+
+ /*
+ * Now take care of our buttons
+ */
+ const u32 btnpins = USR_SW1 | USR_SW2;
+
+ /*
+ * PF0 is locked by default. We need to unlock the GPIO_CR register,
+ * then enable PF0 commit. After we do this, we can setup PF0. If we
+ * don't do this, any configuration done to PF0 is lost, and we will not
+ * have a PF0 interrupt.
+ */
+ GPIO_LOCK(GPIOF) = 0x4C4F434B;
+ GPIO_CR(GPIOF) |= USR_SW2;
+
+ /* Configure pins as inputs. */
+ GPIO_DIR(GPIOF) &= ~btnpins;
+ /* Enable digital function on the pins. */
+ GPIO_DEN(GPIOF) |= btnpins;
+ /* Pull-up the pins. We don't have an external pull-up */
+ GPIO_PUR(GPIOF) |= btnpins;
+}
- GPIO_DIR(GPIOF) |= outpins; /* Configure outputs. */
- GPIO_DEN(GPIOF) |= outpins; /* Enable digital function on outputs. */
+/*
+ * IRQ setup:
+ * Trigger an interrupt whenever a button is depressed.
+ */
+static void irq_setup(void)
+{
+ const u32 btnpins = USR_SW1 | USR_SW2;
+ /* Configure interrupt as edge-sensitive */
+ GPIO_IS(GPIOF) &= ~btnpins;
+ /* Interrupt only respond to rising or falling edge (single-edge) */
+ GPIO_IBE(GPIOF) &= ~btnpins;
+ /* Trigger interrupt on rising-edge (when button is depressed) */
+ GPIO_IEV(GPIOF) |= btnpins;
+ /* Finally, Enable interrupt */
+ GPIO_IM(GPIOF) |= btnpins;
+ /* Enable the interrupt in the NVIC as well */
+ nvic_enable_irq(NVIC_GPIOF_IRQ);
}
#define FLASH_DELAY 800000
+static void delay(void)
+{
+ int i;
+ for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
+ __asm__("nop");
+}
+
int main(void)
{
int i;
+ clock_setup();
gpio_setup();
+ irq_setup();
- /* Blink STATUS LED (PF0) on the board. */
+ /* Blink each color of the RGB LED in order. */
while (1) {
/*
* Flash the Red diode
*/
- gpio_set(GPIOF, GPIO1);
-
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
-
- gpio_clear(GPIOF, GPIO1);
-
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
+ gpio_set(RGB_PORT, LED_R);
+ delay(); /* Wait a bit. */
+ gpio_clear(RGB_PORT, LED_R);
+ delay(); /* Wait a bit. */
/*
* Flash the Green diode
*/
- gpio_set(GPIOF, GPIO3);
-
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
-
- gpio_clear(GPIOF, GPIO3);
-
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
+ gpio_set(RGB_PORT, LED_G);
+ delay(); /* Wait a bit. */
+ gpio_clear(RGB_PORT, LED_G);
+ delay(); /* Wait a bit. */
/*
* Flash the Blue diode
*/
- gpio_set(GPIOF, GPIO2);
-
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
+ gpio_set(RGB_PORT, LED_B);
+ delay(); /* Wait a bit. */
+ gpio_clear(RGB_PORT, LED_B);
+ delay(); /* Wait a bit. */
+ }
- gpio_clear(GPIOF, GPIO2);
+ return 0;
+}
- for (i = 0; i < FLASH_DELAY; i++) /* Wait a bit. */
- __asm__("nop");
+void gpiof_isr(void)
+{
+ if (GPIO_RIS(GPIOF) & USR_SW1) {
+ /* SW1 was just depressed */
+ bypass = !bypass;
+ if (bypass) {
+ rcc_pll_bypass_enable();
+ /*
+ * The divisor is still applied to the raw clock.
+ * Disable the divisor, or we'll divide the raw clock.
+ */
+ SYSCTL_RCC &= ~SYSCTL_RCC_USESYSDIV;
+ }
+ else
+ {
+ rcc_change_pll_divisor(plldiv[ipll]);
+ }
+ /* Clear interrupt source */
+ GPIO_ICR(GPIOF) = USR_SW1;
}
- return 0;
+ if (GPIO_RIS(GPIOF) & USR_SW2) {
+ /* SW2 was just depressed */
+ if (!bypass) {
+ if (plldiv[++ipll] == 0)
+ ipll = 0;
+ rcc_change_pll_divisor(plldiv[ipll]);
+ }
+ /* Clear interrupt source */
+ GPIO_ICR(GPIOF) = USR_SW2;
+ }
}
diff --git a/examples/stm32/f4/stm32f4-discovery/usart_irq/Makefile b/examples/stm32/f4/stm32f4-discovery/usart_irq/Makefile
new file mode 100644
index 0000000..b7bbd14
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/usart_irq/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 = usart_irq
+
+LDSCRIPT = ../stm32f4-discovery.ld
+
+include ../../Makefile.include
+
diff --git a/examples/stm32/f4/stm32f4-discovery/usart_irq/README b/examples/stm32/f4/stm32f4-discovery/usart_irq/README
new file mode 100644
index 0000000..ac859a9
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/usart_irq/README
@@ -0,0 +1,14 @@
+------------------------------------------------------------------------------
+README
+------------------------------------------------------------------------------
+
+This example program echoes data sent in on USART2 on the
+ST STM32F4DISCOVERY eval board. Uses interrupts for that purpose.
+
+Connect your TTL RX device line to PA2 on the discovery board.
+Connect your TTL TX device line to PA3 on the discovery board.
+
+The terminal settings for the receiving device/PC are 38400 8n1.
+
+The sending is done in a blocking way in the code.
+
diff --git a/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c b/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c
new file mode 100644
index 0000000..8e7aa7f
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c
@@ -0,0 +1,115 @@
+/*
+ * 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) 2013 Piotr Esden-Tempski <piotr@esden.net>
+ *
+ * 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>
+#include <libopencm3/cm3/nvic.h>
+
+void clock_setup(void)
+{
+ /* 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)
+{
+ /* Enable the USART2 interrupt. */
+ nvic_enable_irq(NVIC_USART2_IRQ);
+
+ /* Setup GPIO pins for USART2 transmit. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+
+ /* Setup GPIO pins for USART2 receive. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO3);
+ gpio_set_output_options(GPIOA, GPIO_OTYPE_OD, GPIO_OSPEED_25MHZ, GPIO3);
+
+ /* Setup USART2 TX and RX pin as alternate function. */
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO3);
+
+ /* 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_RX);
+ usart_set_parity(USART2, USART_PARITY_NONE);
+ usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+
+ /* Enable USART2 Receive interrupt. */
+ usart_enable_rx_interrupt(USART2);
+
+ /* 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);
+}
+
+int main(void)
+{
+ clock_setup();
+ gpio_setup();
+ usart_setup();
+
+ while (1) {
+ __asm__("NOP");
+ }
+
+ return 0;
+}
+
+void usart2_isr(void)
+{
+ static u8 data = 'A';
+
+ /* Check if we were called because of RXNE. */
+ if (((USART_CR1(USART2) & USART_CR1_RXNEIE) != 0) &&
+ ((USART_SR(USART2) & USART_SR_RXNE) != 0)) {
+
+ /* Indicate that we got data. */
+ gpio_toggle(GPIOD, GPIO12);
+
+ /* Retrieve the data from the peripheral. */
+ data = usart_recv(USART2);
+
+ /* Enable transmit interrupt so it sends back the data. */
+ usart_enable_tx_interrupt(USART2);
+ }
+
+ /* Check if we were called because of TXE. */
+ if (((USART_CR1(USART2) & USART_CR1_TXEIE) != 0) &&
+ ((USART_SR(USART2) & USART_SR_TXE) != 0)) {
+
+ /* Put data into the transmit register. */
+ usart_send(USART2, data);
+
+ /* Disable the TXE interrupt as we don't need it anymore. */
+ usart_disable_tx_interrupt(USART2);
+ }
+}