SoftSerial on 8Mhz board with 1200 baud

[keesj]

Hi,

I am using SoftSerial on a 8Mhz board and I am trying to communicate at 1200 baud (that's all the transmitter I own allows). I am currently only sending data in a loop.

Code: [Select]

#include <TinyPinChange.h>
#include <SoftSerial.h>
.
#define DEBUG_TX_RX_PIN         0 //Adjust here your Tx/Rx debug pin
.
SoftSerial MyDbgSerial(DEBUG_TX_RX_PIN, DEBUG_TX_RX_PIN, true); //true allows to connect to a regular RS232 without RS232 line driver
.
void setup()
{
  MyDbgSerial.begin(1200); //After MyDbgSerial.begin(), the serial port is in rxMode by default
  MyDbgSerial.txMode(); //Before sending a message, switch to txMode
  MyDbgSerial.println(F("\nDebug enabled"));
  MyDbgSerial.rxMode(); //switch to rxMode to be ready to receive some commands
}
.
void loop()
{
  delay(500);
  MyDbgSerial.txMode();
  MyDbgSerial.print("Hello: ");
      MyDbgSerial.rxMode();
  if(MyDbgSerial.available())
  {
    MyDbgSerial.read();

  }
}


Afther running this code (Against the official arduino) I figured out the transmit times where far of so
I used a logic analyzer to tweak  the table in DigisparkSoftSerial/SoftSerial.cpp to make it all work

Code: [Select]

diff --git a/libraries/DigisparkSoftSerial/SoftSerial.cpp b/libraries/DigisparkSoftSerial/SoftSerial.cpp
index 03b3b33..45ffbc0 100755
--- a/libraries/DigisparkSoftSerial/SoftSerial.cpp
+++ b/libraries/DigisparkSoftSerial/SoftSerial.cpp
@@ -121,8 +121,8 @@ static const DELAY_TABLE table[] PROGMEM =
   { 14400,    30,         75,        75,     72,     },
   { 9600,     50,         114,       114,    112,    },
   { 4800,     110,        233,       233,    230,    },
-  { 2400,     229,        472,       472,    469,    },
-  { 1200,     467,        948,       948,    945,    },
+  { 2400,     229,        472,       472,    600,    },
+  { 1200,     467,        948,       948,    1277,    },
   { 300,      1895,       3805,      3805,   3802,   },
 };

the bit time with that changes is very close to 1000/1200 = 0.8333 ms.
I am expecting this is a bug in the SoftSerial.cpp code but I would like to know for sure. I also found the 2400 baud to be far of. I am willing to update the table if needed( and I did not change things for receiving yet).