[examples] Added CAN example for obldc strip.

examples/stm32/f1/obldc-strip/can/Makefile

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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 = can
+
+LDSCRIPT = ../obldc-strip.ld
+
+include ../../Makefile.include
+

examples/stm32/f1/obldc-strip/can/README

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+This test sets up the CAN interface on Lisa/M and transmits 8 bites every
+100ms. The first byte is being incremented in each cycle. The demo also
+receives messages and is displaing the first 4 bits of the first byte on the
+board LEDs.

examples/stm32/f1/obldc-strip/can/can.c

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 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/f1/rcc.h>
+#include <libopencm3/stm32/f1/flash.h>
+#include <libopencm3/stm32/f1/gpio.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/can.h>
+
+struct can_tx_msg {
+	u32 std_id;
+	u32 ext_id;
+	u8 ide;
+	u8 rtr;
+	u8 dlc;
+	u8 data[8];
+};
+
+struct can_rx_msg {
+	u32 std_id;
+	u32 ext_id;
+	u8 ide;
+	u8 rtr;
+	u8 dlc;
+	u8 data[8];
+	u8 fmi;
+};
+
+struct can_tx_msg can_tx_msg;
+struct can_rx_msg can_rx_msg;
+
+void gpio_setup(void)
+{
+        /* Enable Alternate Function clock. */
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN);
+
+	/* Enable GPIOB clock. */
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN);
+
+	/* Preconfigure LEDs. */
+	gpio_set(GPIOB, GPIO4);  /* LED green off */
+	gpio_set(GPIOB, GPIO5);  /* LED red off */
+
+	/* Configure LED GPIOs. */
+	gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ,
+		      GPIO_CNF_OUTPUT_PUSHPULL, GPIO4);
+	gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ,
+		      GPIO_CNF_OUTPUT_PUSHPULL, GPIO5);
+
+	/* Configure PB4 as GPIO. */
+	AFIO_MAPR |= AFIO_MAPR_SWJ_CFG_FULL_SWJ_NO_JNTRST;
+
+}
+
+void systick_setup(void)
+{
+	/* 64MHz / 8 => 8000000 counts per second */
+	systick_set_clocksource(STK_CTRL_CLKSOURCE_AHB_DIV8);
+
+	/* 8000000/8000 = 1000 overflows per second - every 1ms one interrupt */
+	systick_set_reload(8000);
+
+	systick_interrupt_enable();
+
+	/* Start counting. */
+	systick_counter_enable();
+}
+
+void can_setup(void)
+{
+	/* Enable peripheral clocks. */
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN);
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN);
+	rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_CAN1EN);
+
+	AFIO_MAPR |= AFIO_MAPR_CAN1_REMAP_PORTB;
+
+	/* Configure CAN pin: RX (input pull-up). */
+	gpio_set_mode(GPIO_BANK_CAN1_PB_RX, GPIO_MODE_INPUT,
+		      GPIO_CNF_INPUT_PULL_UPDOWN, GPIO_CAN1_PB_RX);
+	gpio_set(GPIO_BANK_CAN1_PB_RX, GPIO_CAN1_PB_RX);
+
+	/* Configure CAN pin: TX. */
+	gpio_set_mode(GPIO_BANK_CAN1_PB_TX, GPIO_MODE_OUTPUT_50_MHZ,
+		      GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_CAN1_PB_TX);
+
+	/* NVIC setup. */
+	nvic_enable_irq(NVIC_USB_LP_CAN_RX0_IRQ);
+	nvic_set_priority(NVIC_USB_LP_CAN_RX0_IRQ, 1);
+
+	/* Reset CAN. */
+	can_reset(CAN1);
+
+	/* CAN cell init.
+	 * Setting the bitrate to 1MBit. APB1 = 32MHz, 
+	 * prescaler = 2 -> 16MHz time quanta frequency.
+	 * 1tq sync + 9tq bit segment1 (TS1) + 6tq bit segment2 (TS2) = 
+	 * 16time quanto per bit period, therefor 16MHz/16 = 1MHz
+	 */
+	if (can_init(CAN1,
+		     false,           /* TTCM: Time triggered comm mode? */
+		     true,            /* ABOM: Automatic bus-off management? */
+		     false,           /* AWUM: Automatic wakeup mode? */
+		     false,           /* NART: No automatic retransmission? */
+		     false,           /* RFLM: Receive FIFO locked mode? */
+		     false,           /* TXFP: Transmit FIFO priority? */
+		     CAN_BTR_SJW_1TQ,
+		     CAN_BTR_TS1_9TQ,
+		     CAN_BTR_TS2_6TQ,
+		     2))             /* BRP+1: Baud rate prescaler */
+	{
+		gpio_clear(GPIOB, GPIO4); /* LED green on */
+		gpio_set(GPIOB, GPIO5);   /* LED red off */
+
+		/* Die because we failed to initialize. */
+		while (1)
+			__asm__("nop");
+	}
+
+	/* CAN filter 0 init. */
+	can_filter_id_mask_32bit_init(CAN1,
+				0,     /* Filter ID */
+				0,     /* CAN ID */
+				0,     /* CAN ID mask */
+				0,     /* FIFO assignment (here: FIFO0) */
+				true); /* Enable the filter. */
+
+	/* Enable CAN RX interrupt. */
+	can_enable_irq(CAN1, CAN_IER_FMPIE0);
+}
+
+void sys_tick_handler(void)
+{
+	static u8 data[8] = {0, 1, 2, 0, 0, 0, 0, 0};
+
+	/* We call this handler every 1ms so every 1ms = 0.001s
+	 * resulting in 1000Hz message rate.
+	 */
+
+	/* Transmit CAN frame. */
+	data[0]++;
+	if (can_transmit(CAN1,
+			 0,     /* (EX/ST)ID: CAN ID */
+			 false, /* IDE: CAN ID extended? */
+			 false, /* RTR: Request transmit? */
+			 8,     /* DLC: Data length */
+			 data) == -1)
+	{
+		gpio_set(GPIOB, GPIO4);   /* LED green off */
+		gpio_clear(GPIOB, GPIO5); /* LED red on */
+	}
+}
+
+void usb_lp_can_rx0_isr(void)
+{
+	u32 id, fmi;
+	bool ext, rtr;
+	u8 length, data[8];
+
+	can_receive(CAN1, 0, false, &id, &ext, &rtr, &fmi, &length, data);
+
+	if (data[0] & 0x40)
+		gpio_clear(GPIOB, GPIO4);
+	else
+		gpio_set(GPIOB, GPIO4);
+
+	if (data[0] & 0x80)
+		gpio_clear(GPIOB, GPIO5);
+	else
+		gpio_set(GPIOB, GPIO5);
+
+	can_fifo_release(CAN1, 0);
+}
+
+int main(void)
+{
+	rcc_clock_setup_in_hsi_out_64mhz();
+	gpio_setup();
+	can_setup();
+	systick_setup();
+
+	while (1); /* Halt. */
+
+	return 0;
+}