High bit rate in Arduino Mega - arduino

Question

I am calculating throughput of BLE module using Arduino Mega. Module works on 3.3V so i have Logic Level Shifter between BLE and Arduino. BLE UART is set at 115200 and is sending data at the speed of 64Kbps(verified using CC2540 BLE packet sniffer). Packet send by BLE are in this format in hex:400102030405060708090A0B0C0D0E0F1011121323{40=#,23=#}. I am sending 100 number of packets.Here is the abstract of my code. Code works fine for lower bit rate 32Kbps but not for 64Kbs(BLE Connection interval to 10ms). It does not show any result in this bit rate.
void loop()
{
if(rxflag)
{
rxflag = false;
switch(rxState)
{
case get_first_header:
if(rxChar=='#')
{
startPoint=millis();
rxState=get_last_header;
}
break;
case get_last_header:
if(rxChar=='#')
{
packetNo++;
if(packetNo==100)
{
endPoint=millis();
totalTime= endPoint-startPoint;
Serial.print("Total Time of Packet=");
Serial.println(totalTime);
}
break;
}
}
}
void serialEvent1()
{
if (Serial1.available()>0)
{
rxChar = (char)Serial1.read();
rxflag = true;
}
}

Answer 1

When you 'purge' the serial buffer:
void serialEvent1()
{
if (Serial1.available()>0)
{
rxChar = (char)Serial1.read(); // was previous value of rxChar read ? mystery...
// this is a serious problem.
// 1 byte at a time? This can slow down
rxflag = true; // reception quite a bit, esp. if there
} // is xon/xoff.
}
When you have an event that's been set in an interrupt routine, you need to reset it before reading the data, unless you use the flag as a lock for interrupt data.
Here's what you should consider to dramatically improve throughput and reduce receive errors.
void serialEvent1()
{
rxflag = true;
}
//...
void lopp()
{
// ...
if (rxflag)
{
rxflag = false; // reset/read order is to avoid stalling.
while (Serial1.available())
{
// reading 4 or up 16 bytes at a time on a local buffer
// would help the tiny mega get this done job done faster.
//
// char buffer[8] buffer; // 2 dwords on the stack. don't overuse!
//
char c = (char)Serial.read();
// run state machine...
}
}
// ...
}