/*
 * Copyright (C) 2016 Michael Andersen <m.andersen@cs.berkeley.edu>
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @defgroup    sys_stdio_rtt STDIO over SEGGER RTT
 * @ingroup     sys_stdio
 *
 * @brief       STDIO mapping for running the STDIO over SEGGER's RTT interface
 *
 *
 * ## RTT STDIO
 *
 * This module will allow communication using SEGGER's Real Time Terminal protocol.
 * Briefly, it replaces UART stdio with a set of ringbuffers that are manipulated
 * over JTAG. There are several advantages to this system. The biggest is that
 * writing to stdout is extremely fast (as you are just copying to memory). This
 * is useful if you are adding print statements in timing-sensitive code as part
 * of debugging. The other advantage is that it frees your UART for other use
 * and enables stdio on platforms that do not have a UART.
 *
 * To use this module, add
 *
 * ```
 * USEMODULE += stdio_rtt
 * ```
 *
 * to your makefile. By default the module will drop bytes written to stdout if the
 * buffer is full. If you know for certain that the debugger is attached, you
 * can obtain lossless stdout by adding
 *
 * ```
 * CFLAGS += -DSTDIO_RTT_ENABLE_BLOCKING_STDOUT
 * ```
 *
 * to your makefile. Note well that if you do NOT plug in the debugger and run
 * the SEGGER RTT software (or compatible software) this will then lock up the
 * system as it waits forever. Typically you would only define this during
 * development on the lab bench.
 *
 * If you are printing significant data out (pages a second), you can increase
 * your stdout bandwidth by lowering the poll interval. The default is 50ms.
 * A choice of 5ms is good during printf-heavy debugging:
 *
 * ```
 * CFLAGS += -DSTDIO_POLL_INTERVAL_MS=5U
 * ```
 *
 * SEGGER RTT supports stdin as well, and this is enabled by default. It requires
 * polling the stdin ringbuffer, however, which on low duty cycle systems
 * can increase the number of unnecessary wakeups from sleep. To disable stdin,
 * add this to your makefile:
 *
 * ```
 * CFLAGS += -DSTDIO_RTT_DISABLE_STDIN
 * ```
 *
 * @note    Currently, `stdio_rtt` is only supported when OpenOCD or J-Link is
 *          used as programmer.
 *
 */