Hi all
I am trying Serial library currently, and there is a problem is Transfer to fast and Serial interface stuck.
My setting
1.Baud rate = 115200bps
2.Transfer packet size from pc to arduino= 34 bytes
3.Every "3ms" send packet (sniffer by Accessport Serial monitor)
4.Serial buffer size = 128bytes
If I sending packets continually , it works about 2 seconds , and than Serial port will stop any action.
sniffer a "purge" action from Serial monitor.
Here is my question.
In my concept. 115200bps = 11520bytes/s = 11.52bytes/ms
[]------------->口
/\ 34bytes
PC arduino
Process cannot handling the data which transfer so fast , so that put the data into the Serial buffer.
waiting Process to execute. Finally the Process will keep working.
To prove of my concept. I stop the data sending from PC. Even through I stop Sending data .
Arduino Serial interface don't haveany action. Unless I reset the Arduino.
I have been thinking during two days. and try to see the file "HardwareSerial.cpp" , because my C language not good enough to understand the code.....
But I still have some thought to trouldshootings.
- In code file "HardwareSerial.cpp" , path is
/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/cores/arduino
int HardwareSerial::read(void)
{
// if the head isn't ahead of the tail, we don't have any characters
if (_rx_buffer_head == _rx_buffer_tail) {
return -1;
} else {
unsigned char c = _rx_buffer[_rx_buffer_tail];
_rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
return c;
}
}
if (_rx_buffer_head == _rx_buffer_tail)
In buffer ring structure , we have to condition in "_rx_buffer_head == _rx_buffer_tail"
First, ring is empty
Second, ring is full
Is any possible....the Serial API think the buffer is empty because sending to fast, therefore Serial have no any action?
-
atmega16u2 USB to Serial cannot handling?
-
My expect is even PC sending data too fast the process can drop or ignore , or anyway to workaround.
Process stop is unacceptable.
Here is my Serial read code.
void Attenuator_c::Get_string2int(){
int clear;
while(Serial.available()>0 && rotary_or_serial == true){
inByte=Serial.read();
if(inByte == 'a' || inByte == 't' || inByte == ' ' || inByte == 'e' || inByte == 'n' ||
inByte == 's' || inByte == 'g' || inByte == 'I' || inByte == 'D' || inByte == 'N' ||
inByte == '*' || inByte == 'r' || inByte == '?' ||
(inByte >= 48 && inByte <=57) && rotary_or_serial == true){
command.concat(inByte);
}
else if(inByte == '\n' || inByte == '\r' && rotary_or_serial == true){
//orignal code
//command.toCharArray(carry,20);
#ifdef DEBUG
//Serial.println(carry); //echo what u type
#endif
/* orignal code
switch (inByte) {
case '\n':
find_address_value();
clear = Serial.read();
break;
case '\r':
find_address_value();
clear = Serial.read();
break;
}
*/
Serial.println(command);
tmp[0] = strtok(&command[0], " ");
while( tmp[string_index] != NULL){
//Serial.println(tmp[string_index]);
string_index=string_index+1;
tmp[string_index] = strtok(NULL, " ");
}
//Serial.println(tmp[0]);
if(strcmp(tmp[0], "atten") == 0){
if(strcmp(tmp[1], "set") == 0){
//Serial.println("Go into Address and Value");
for (_string_index=2; _string_index < string_index ; _string_index=_string_index+2 ) {
Address_int=atoi(tmp[_string_index]); //_string_index=0
value_int=atoi(tmp[_string_index+1])/10;
compare_result=Compare_string_int(Address_int,value_int);
}
}
else if(strcmp(tmp[1], "get") == 0){
p("CH0 = %d dBm \n" , Arduino_Att[0][0]>>1);
p("CH1 = %d dBm \n" , Arduino_Att[1][0]>>1);
p("CH2 = %d dBm \n" , Arduino_Att[2][0]>>1);
p("CH3 = %d dBm \n" , Arduino_Att[3][0]>>1);
//Serial.printf("CH3 = %d dBm \n"), Attenuator[3]);
//Serial.println("On working, get function");
}
else
{
Serial.println("Error");
}
}
else if(strcmp(tmp[0],"*IDN?") == 0){
Serial.println(IDN);
}
else if(strcmp(tmp[0],"reset") == 0){
delay(1);
resetFunc();
}
else{
Serial.println("Fisrt word Error must be atten");
}
string_index=0;
#ifdef DEBUG
//Serial.println("command: "+command);
#endif
clear = Serial.read();
command="";
/*
command="";
command.toCharArray(carry,20);
Address_int=atoi(carry);
value_int=atoi(carry);
*/
}
else{
//Serial.flush();
}
}
}