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lm4f: Add USB to serial (CDCACM) example

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Implements a USB-to-serial adapter, compliant to the CDCACM subclass.
UART1 is used for the TX/RX lines. Although UART1 also has lines for flow
control, they are not used. Instead, the control lines are implemented in
software via GPIOA.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
This commit is contained in:
Alexandru Gagniuc
2013-05-15 00:21:33 -05:00
committed by Piotr Esden-Tempski
parent f5b0aa5638
commit 28f92cce2b
6 changed files with 767 additions and 0 deletions
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examples/lm4f/stellaris-ek-lm4f120xl/usb_to_serial_cdcacm/uart.c Normal file
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/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2012-2013 Alexandru Gagniuc <mr.nuke.me@gmail.com>
*
* 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 <http://www.gnu.org/licenses/>.
*/
/**
* \addtogroup Examples
*
*/
/*
* Pins handled by hw peripheral:
* Tx <-> PB1
* Rx <-> PB0
* Input pins handled manually via interrupts:
* DCD <-> PA2
* DSR <-> PA3
* RI <-> PA4
* CTS <-> PA5 (UNUSED)
* Output pins handled via commands from the host:
* DTR <-> PA6
* RTS <-> PA7
*/
#include "usb_to_serial_cdcacm.h"
#include <libopencm3/lm4f/rcc.h>
#include <libopencm3/lm4f/uart.h>
#include <libopencm3/lm4f/nvic.h>
static void uart_ctl_line_setup(void)
{
u32 inpins, outpins;
inpins = PIN_DCD | PIN_DSR | PIN_RI | PIN_CTS;
outpins = PIN_DTR | PIN_RTS;
gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, outpins);
gpio_mode_setup(GPIOA, GPIO_MODE_INPUT, GPIO_PUPD_PULLUP, inpins);
}
void uart_init(void)
{
/* Enable GPIOA and GPIOB in run mode. */
periph_clock_enable(RCC_GPIOB);
periph_clock_enable(RCC_GPIOA);
uart_ctl_line_setup();
/* Mux PB0 and PB1 to AF1 (UART1 in this case) */
gpio_set_af(GPIOB, 1, GPIO0 | GPIO1);
/* Enable the UART clock */
periph_clock_enable(RCC_UART1);
/* Disable the UART while we mess with its setings */
uart_disable(UART1);
/* Configure the UART clock source */
uart_clock_from_piosc(UART1);
/* We don't make any other settings here. */
uart_enable(UART1);
/* Ping us when something comes in */
uart_enable_rx_interrupt(UART1);
nvic_enable_irq(NVIC_UART1_IRQ);
}
u8 uart_get_ctl_line_state(void)
{
return gpio_read(GPIOA, PIN_RI | PIN_DSR | PIN_DCD);
}
void uart_set_ctl_line_state(u8 dtr, u8 rts)
{
u8 val = 0;
val |= dtr ? PIN_DTR : 0;
val |= rts ? PIN_RTS : 0;
gpio_write(GPIOA, PIN_DTR | PIN_RTS, val);
}
void uart1_isr(void)
{
u8 rx;
rx = uart_recv(UART1);
glue_data_recieved_cb(&rx, 1);
uart_clear_interrupt_flag(UART1, UART_INT_RX);
}