Arduino library for Segger RTT on arm and risc-v Arduinos
With RTTStream an stm32duino can do screen output on a pc, and get keyboard input from a pc, without using usb or serials. Connection is using the SWD or JTAG port.
To use RTTStream you need a Segger JLink debugger probe. Depending upon your needs, Open Source alternatives may also be suitable.
RTTStream only runs on arduinos with arm or risc-v processors, sorry.
Use RTTStream just like you would use Serial:
#include <RTTStream.h>
RTTStream rtt;
void setup() {
rtt.println("hello world!");
}
void loop() {
}
This is an example of a debugging session of a STM32F103 Blue Pill on linux.
Connect a Segger J-Link probe to the SWD port of your arduino, and to the usb of your pc.
Connections between blue pill and J-Link:
| Blue pill | J-Link | J-Link Pin | J-Link Mini Pin |
|---|---|---|---|
| +3.3V | VTREF | 1 | 1 |
| SWDIO | SWDIO | 7 | 2 |
| SWCLK | SWCLK | 9 | 4 |
| GND | GND | 4 | 3 |
Open a window and start the gdb server:
JLinkGDBServer -device STM32F103R8 -if SWD -speed 4000
Open another window and start the RTT terminal. This is where the messages from the arduino program will appear, and where you can type keyboard input.
JLinkRTTClient
Start the debugger, download and run your program:
$ arm-none-eabi-gdb
(gdb) target extended-remote 127.0.0.1:2331
(gdb) file StreamTest.ino.elf
(gdb) load
(gdb) run
or, abbreviated:
$ arm-none-eabi-gdb
(gdb) tar ext :2331
(gdb) fil StreamTest.ino.elf
(gdb) lo
(gdb) r
Switch to the window where JLinkRTTClient is running to read program messages, and to type program input:
rtt stream test
char: a
string: the quick brown fox jumps over a lazy dog
int: 12345
float: 3.14
printf char: a signed int: -12345 unsigned int: 12345
printf hex int: 12345 string: 12345 pointer: 20000090
enter an int: 23456
value: 23456
enter a float: 2.71828
value: 2.72
enter a string and wait 5 seconds: qwerty
string: qwerty
rtt stream test end
RTTStream contains SEGGER RTT source files. Some Arduino boards already include SEGGER RTT as part of the board package, e.g. nrf52.
To avoid duplicates, if the Arduino board package already contains the files SEGGER_RTT.h, SEGGER_RTT.c and SEGGER_RTT_Conf.h, please remove the files SEGGER_RTT.h, SEGGER_RTT.c and SEGGER_RTT_Conf.h from libraries/RTT_Stream/src/
This way there is only one version of SEGGER RTT.
- The Eclipse development environment has a plugin to automate using Segger J-Link.
- Open source projects that support RTT are OpenOCD, Black Magic Probe, probe-rs and others.
not truncated