Receiving only serial data in the power of 2 when sending the alphabeth - encoding

Question

I am trying to perform a simple experiment with an Arduino Uno and the BlueSmirf Bluetooth module from Sparkfun (documentation).
My hardware setup looks like this:
Arduino(power through USB)->BlueSmirf ---(bluetooth)--> PC(no wired connection the the Arduino)->RealTerm
On the Arduino, the following sketch is running:
#include <SoftwareSerial.h>
int txPin = 2;
int rxPin = 3;
SoftwareSerial bluetooth(txPin, rxPin);
void setup() {
bluetooth.begin(115200);
delay(100);
}
void loop() {
String textToSend = "abcdefghijklmnopqrstuvw123456789";
bluetooth.print(textToSend);
delay(5000);
}
Now, the bluetooth connects to the PC just fine, but when I inspect the COM port in RealTerm, I only get the following output:
abdhp1248
Where did the remaining letters and numbers go? It seems like all of the letters that follow the power of two, (i.e. a=1, b=2, d=4, h=8, p=16) print, but none of the rest. Is this just a coincidence?

Answer 1

I think you're running the serial port too fast. As per the comments in the sparkfun BlueSmirf example at https://learn.sparkfun.com/tutorials/using-the-bluesmirf - "115200 can be too fast at times for NewSoftSerial to relay the data reliably".
Reduce the baud rate to 9600 using the code example below, modified from the above web page.
/*
Example Bluetooth Serial Passthrough Sketch
by: Jim Lindblom
SparkFun Electronics
date: February 26, 2013
license: Public domain
This example sketch converts an RN-42 bluetooth module to
communicate at 9600 bps (from 115200), and passes any serial
data between Serial Monitor and bluetooth module.
*/
#include <SoftwareSerial.h>
int bluetoothTx = 2; // TX-O pin of bluetooth mate, Arduino D2
int bluetoothRx = 3; // RX-I pin of bluetooth mate, Arduino D3
SoftwareSerial bluetooth(bluetoothTx, bluetoothRx);
void setup()
{
bluetooth.begin(115200); // The Bluetooth Mate defaults to 115200bps
bluetooth.print("$"); // Print three times individually
bluetooth.print("$");
bluetooth.print("$"); // Enter command mode
delay(100); // Short delay, wait for the Mate to send back CMD
bluetooth.println("U,9600,N"); // Temporarily Change the baudrate to 9600, no parity
// 115200 can be too fast at times for NewSoftSerial to relay the data reliably
bluetooth.begin(9600); // Start bluetooth serial at 9600
}
void loop()
{
String textToSend = "abcdefghijklmnopqrstuvw123456789";
bluetooth.print(textToSend);
delay(5000);
}