/* * 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 void clock_setup(void) { rcc_clock_setup_in_hse_8mhz_out_24mhz(); /* Enable GPIOC clock. */ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPCEN); /* Enable clocks for GPIO port A (for GPIO_USART1_TX) and USART1. */ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN); rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_USART1EN); } void usart_setup(void) { /* Setup GPIO pin GPIO_USART1_TX/GPIO9 on GPIO port A for transmit. */ gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX); /* Setup UART parameters. */ // usart_set_baudrate(USART1, 38400); /* TODO usart_set_baudrate() doesn't support 24MHz clock (yet). */ /* This is the equivalent: */ USART_BRR(USART1) = (u16)((24000000 << 4) / (38400 * 16)); usart_set_databits(USART1, 8); usart_set_stopbits(USART1, USART_STOPBITS_1); usart_set_mode(USART1, USART_MODE_TX); usart_set_parity(USART1, USART_PARITY_NONE); usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE); /* Finally enable the USART. */ usart_enable(USART1); } void gpio_setup(void) { /* Set GPIO9 (in GPIO port C) to 'output push-pull'. [LED] */ gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO9); } int main(void) { int i, j = 0, c = 0; clock_setup(); gpio_setup(); usart_setup(); /* Blink the LED (PC9) on the board with every transmitted byte. */ while (1) { gpio_toggle(GPIOC, GPIO9); /* LED on/off */ usart_send_blocking(USART1, c + '0'); /* USART1: Send byte. */ c = (c == 9) ? 0 : c + 1; /* Increment c. */ if ((j++ % 80) == 0) { /* Newline after line full. */ usart_send_blocking(USART1, '\r'); usart_send_blocking(USART1, '\n'); } for (i = 0; i < 800000; i++) /* Wait a bit. */ __asm__("NOP"); } return 0; }