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#include "clock.h"
#include "delay.h"
#include "gpio.h"
#include "spin.h"
#include "usart.h"
volatile uint32_t delay_amt = 20000000 / 4;
int enable_usart2(uint32_t baud_rate)
{
__IO gpio_port_t* port_a = enable_gpio(GPIO_PORT_A);
enable_hsi(&RCC, true);
// Turn on the clock for the USART2 peripheral
set_usart2_clock_src(&RCC, USART_CLK_SRC_HSI16);
set_usart2_clock_enabled(&RCC, true);
// Configure the I/O pins. Will use PA2 as TX and PA15 as RX so setup for
// alternate function
set_gpio_pin_mode(port_a, PIN_2, MODE_ALTERNATE);
set_gpio_pin_mode(port_a, PIN_15, MODE_ALTERNATE);
set_gpio_alternate_function(port_a, PIN_2, AFN_7);
set_gpio_alternate_function(port_a, PIN_15, AFN_3);
// De-assert reset of USART2
RCC.apb1rst1_r &= ~BIT(17);
// Configure the USART
// disable USART first to allow setting of other control bits
// This also disables parity checking and enables 16 times oversampling
USART2.c_r1 = 0;
USART2.c_r2 = 0;
USART2.c_r3 = 0;
usart_set_divisor(&USART2, 16000000 / baud_rate);
usart_set_enabled(&USART2, USART_ENABLE_TX | USART_ENABLE_RX);
}
int enable_usart1(uint32_t baud_rate)
{
/* Enable the GPIO bus. */
__IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
/* Enable the USART clock. */
RCC.apb2en_r |= BIT(14);
/* == Configure the IO Pins. == */
/* GPIO D5 (Port B pin 6) is USART1 Tx,
* GPIO D6 (Port B pin 7) is USART1 Rx. */
set_gpio_pin_mode(port_b, PIN_6, MODE_ALTERNATE);
set_gpio_pin_mode(port_b, PIN_7, MODE_ALTERNATE);
/* Set the GPIO pins to use the USART alternate function. */
set_gpio_alternate_function(port_b, PIN_6, AFN_7);
set_gpio_alternate_function(port_b, PIN_7, AFN_7);
RCC.apb2rst_r &= ~BIT(14); /* De-assert reset of USART1 */
uint32_t baud_rate_div = 80000000 / baud_rate;
USART1.c_r1 = 0;
USART1.c_r2 = 0;
USART1.c_r3 = 0;
USART1.br_r = baud_rate_div;
USART1.c_r1 |= BIT(3) | BIT(2);
USART1.c_r1 |= BIT(0);
/* Enable the transmitter and the receiver. */
usart_set_enabled(&USART1, USART_ENABLE_TX);
asm volatile(" cpsie i ");
}
/* Main function. This gets executed from the interrupt vector defined above. */
int main()
{
/* Enable the GPIO port B. */
__IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
gpio_output_pin_t pin1 = set_gpio_pin_output(port_b, PIN_1);
/* Enable a higher clock frequency. */
set_system_clock_MHz(80);
enable_usart2(115200);
pin_on(pin3);
usart_transmit_str(&USART2, "Hello, World\n");
for(;;);
}
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