Issue with SoftwareSerialwithhalfduplex working in 8n2

Projects Networking, Protocols, and Devices
1

Good evening
I am quite newbie in Arduino with limited background in electronics
I try to use SoftwareSerialwithhalfduplex library and it is working well between 2 Arduinos
I implemented a simple sketch to send smbus command to a Lithium battery but get no answer.
I thus checked with oscilloscope the bit sequence and it appears to be 8n2 (2 stop bits)
I thought this library was sending data under 8n1 “format “?
Could someone confirm me if there is a way to adapt the library to send with 8n1 protocol or maybe there is a more adapted library?
Thanks in advance

2

A delay after sending each byte will appear as extra stop bits! Is your program doing that?

Paul

3

You can do:

Serial.begin(<speed>, SERIAL_8N2);
4

Thanks a lot for these information.
I will test and keep you informed

5

@Paul,
Hi Paul, I have no delay in the program.
See below.

[code]
#include <SoftwareSerialWithHalfDuplex.h>

#define comPin 10

// add arguments of false (for inverse_logic?), false (for full-duplex?) for half duplex.
// you can then use the same pin for both transmit and receive.
SoftwareSerialWithHalfDuplex debugPort(comPin,comPin,false,false);

String readString;


void setup(){
  debugPort.begin(38400);         // to connect with other devices
  Serial.begin(9600);            // to see who's connected
}

void loop(){

delay(3000);
debugPort.write(0x10);
debugPort.write(0x01);
debugPort.write(0x04);
debugPort.write(0x07);
debugPort.write(0x0b);
debugPort.write((byte)0x00);
debugPort.write(0x07);
debugPort.write(0x01);
debugPort.write(0x6b);
debugPort.write(0x10);
debugPort.write(0x04);
//debugPort.end(); // utilisé pour vider le buffer car sans cela, la boucle ci dessous lisait des 0000, autant que de 0x envoyés en debugPort.write!?
//debugPort.begin(38400);
debugPort.flush();

for (int i=0; i<40; i++) {
      while(!debugPort.available()); // wait for a character
    int incomingByte = debugPort.read();
    Serial.write(incomingByte);
    }

    delay(1000);
}

[/code]

6

PErhaps it is in here: SoftwareSerialWithHalfDuplex.h>, when the check for a character being returned on the receive line.

Paul

7

Dear Paul,

This is out of my competence to investigate the SoftwareSerialWithHalfDuplex.h.

I also noticed a strange behaviour. Transmission is as follow for every byte:
1 bit start /8 data bits and then 2 stop bits.
The duration of these 2 stop bits is not consistent.
Normally every bit is about 26us ( corresponding to 38400 baud rate). This is true for every bit (Start/Data) but most of the 2 Stop bits have a total duration of 46,8us (instead of 52us).

Any idea?

8

@POWER_BROKER

Hi, it seems there is no such argument available when using SoftwareSerialWithHalfDuplex.h

9

Technically, stop bits can be as long as needed, could be minutes long. The actual minimum length is what is important.

Paul