/* * This file is part of the libopencm3 project. * * Copyright (C) 2009 Uwe Hermann * * 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 static void clock_setup(void) { rcc_clock_setup_in_hse_8mhz_out_72mhz(); /* Enable GPIOA clock (for LED GPIOs). */ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN); /* Enable clocks for GPIO port B (for GPIO_USART1_TX) and USART1. */ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN); rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN); rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_USART1EN); } static void usart_setup(void) { /* Enable the USART1 interrupt. */ nvic_enable_irq(NVIC_USART1_IRQ); /* Enable USART1 pin software remapping. */ AFIO_MAPR |= AFIO_MAPR_USART1_REMAP; /* Setup GPIO pin GPIO_USART1_RE_TX on GPIO port B for transmit. */ gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_RE_TX); /* Setup GPIO pin GPIO_USART1_RE_RX on GPIO port B for receive. */ gpio_set_mode(GPIOB, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO_USART1_RE_RX); /* Setup UART parameters. */ usart_set_baudrate(USART1, 230400); usart_set_databits(USART1, 8); usart_set_stopbits(USART1, USART_STOPBITS_1); usart_set_parity(USART1, USART_PARITY_NONE); usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE); usart_set_mode(USART1, USART_MODE_TX_RX); /* Enable USART1 Receive interrupt. */ USART_CR1(USART1) |= USART_CR1_RXNEIE; /* Finally enable the USART. */ usart_enable(USART1); } static void gpio_setup(void) { gpio_set(GPIOA, GPIO6 | GPIO7); /* Setup GPIO6 and 7 (in GPIO port A) for LED use. */ gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO6 | GPIO7); } void usart1_isr(void) { static u8 data = 'A'; /* Check if we were called because of RXNE. */ if (((USART_CR1(USART1) & USART_CR1_RXNEIE) != 0) && ((USART_SR(USART1) & USART_SR_RXNE) != 0)) { /* Indicate that we got data. */ gpio_toggle(GPIOA, GPIO6); /* Retrieve the data from the peripheral. */ data = usart_recv(USART1); /* Enable transmit interrupt so it sends back the data. */ USART_CR1(USART1) |= USART_CR1_TXEIE; } /* Check if we were called because of TXE. */ if (((USART_CR1(USART1) & USART_CR1_TXEIE) != 0) && ((USART_SR(USART1) & USART_SR_TXE) != 0)) { /* Indicate that we are sending out data. */ gpio_toggle(GPIOA, GPIO7); /* Put data into the transmit register. */ usart_send(USART1, data); /* Disable the TXE interrupt as we don't need it anymore. */ USART_CR1(USART1) &= ~USART_CR1_TXEIE; } } int main(void) { clock_setup(); gpio_setup(); usart_setup(); /* Wait forever and do nothing. */ while (1) __asm__("nop"); return 0; }