Apologies if this is addressed somewhere - the search is a little overwhelming!
I'm working on a project where I'm using softwareSerial to send data down the line to another arduino's hardware serial port. Sort of a cascade thing going on. What I'm finding is that as long as an arduino is plugged into a computer via USB, and the usb->serial port is enumerated (doesn't even have to be open), it works fine. No problems at all.
But, if I power the arduino off a AC adapter or run the USB into a standalone power supply, the SoftwareSerial doesn't transmit. For example, even the very simple sketch below fails to transmit until I plug in the usb, then it immediately starts working. I'm at a bit of a loss, none of the examples seem to mention anything about this. I'm still something of a noob so I might have missed something simple.
`
#include <SoftwareSerial.h>
SoftwareSerial mySerial(6, 7); // RX, TX
void setup()
{
mySerial.begin(9600);
}
void loop()
{
mySerial.println ("1,1,8");
delay(250);
}