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The Sketch itself doesnt need access to the Software Serial port, just the library. There is also AltSoftSerial which is better than NewSoftSerial in terms of performance, but is even more limited in pin choice.Īt this stage, I have to ask "why those pins?". The Library is going to use the SoftwareSerial library that comes with the Arduino IDE. These are far easier to use and far more efficient than any software serial library. There are 4 hardware USARTs on the ATmega2560. Function of the interrupt pins is described on page 105 onwards of the datasheet. You can see these on the pin mapping diagram for the ATmega2560 (which is correct, AFAIK). The Arduino microcontroller communicates with GSM modem using serial communication protocol and Arduino will decode and check incoming SMS for these three. The short list of: 2 (interrupt 0), 3 (interrupt 1), 18 (interrupt 5), 19 (interrupt 4), 20 (interrupt 3), and 21 (interrupt 2). The Arduino hardware has the built-in support for Serial communications on pins 0 and 1 (Hardware Serial) but in some circumstances such as when these pins are already in-use or you need more Serial ports for debugging, Software Serial may seem to be the solution. The long list of: 10, 11, 12, 13, 50, 51, 52, 53, 62, 63, 64, 65, 66, 67, 68, 69Īre pin change interrupts which are what are required for NewSoftSerial (called SoftSerial in Arduino 1.0 and above). Pin change interrupts trigger as long as any change occurs. External interrupts are more complex and can be configured to trigger on rising and/or falling edges.
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With respect to the contradictory pins there are two types of interrupt pin on the ATmega2560 - external interrupts (INT7 - INT0) and pin change interrupts (PCINT23 - PCINT0). This limits the pins that it can work on though to ones that have pin change interrupts. This uses interrupts and timers, and is far more efficient. In Arduino version 1 and above, SoftSerial was replaced with NewSoftSerial. I would strongly recommend avoiding this. It just uses millis(), digitalRead/Write and blocks when sending or receiving. In Arduino version 0023 and below, SoftSerial was a very basic library written by David Mellis. Important! It has to be the development branch because this allows controlling vescs over software serial.The reason behind the discrepancy in documentation is that the documentation refers to two different versions of the software and it is out of date. This is the library I use for vesc uart control. The command that makes rosserial through the error is this one: ** Define which ports to use as vesc1 */ Ros::Publisher velocity_pub("/report/vel_received", &vel_recieved) SoftwareSerial vesc1_serial(6, 7) // RX, TX
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I can control the vesc with ppm control and rosserial but then I lose all the info I could get back from it using the UART, which is something I would rather not! The rosserial is communicating with the arduino at 56200 BAUD whereas the software serial ( I am using this library because of lack of serial ports ) is set to 19600 BAUD. Joystick sends commands to the arduino over rosserial || the arduino sends the current value to the vesc (vesc being controlled in current mode ) When I did try yesterday to control a VESC through arduino's software serial library, if I do not send any commands to the vesc through UART all is fine and ros is happily connected to the arduino, but the moment I try to send a vesc command (no matter what command i try to send ) I get the following error on the terminal: However, I have never tried using the serial communication on the arduino side, while it is plugged in the computer and the rosserial is running. I have been using rosserial in the past with no issues at all.
Using the arduino software serial library how to#
I am running ROS melodic on ubuntu 18.04 and I have encountered a problem for which I couldn't find any info, or I didn't know how to look for it (which could be possible! ) and I would like your help!