/* * This file is part of the libopencm3 project. * * Copyright (C) 2009 Uwe Hermann * Copyright (C) 2011 Stephen Caudle * Copyright (C) 2013 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 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); } }