/* * This file is part of the libopencm3 project. * * Copyright (C) 2012 Piotr Esden-Tempski * * 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 . */ #include #include #include #include #include #include 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; static 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; } static 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 interrupt every N clock pulses: set reload to N-1 */ systick_set_reload(7999); systick_interrupt_enable(); /* Start counting. */ systick_counter_enable(); } static 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, false, false)) /* 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; }