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Jonathan
Jonathan
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So I'm trying to understand a read method. In this method,

// Read data from buffer
int SoftwareSerial::read()
{
if (!isListening())
  return -1;

// Empty buffer?
if (_receive_buffer_head == _receive_buffer_tail)
  return -1;

// Read from "head"
uint8_t d = _receive_buffer[_receive_buffer_head]; // grab next byte
_receive_buffer_head = (_receive_buffer_head + 1) % _SS_MAX_RX_BUFF;
return d;
}

it looks it receives buffer head. But in the write only a 1 or 0 is being sent as the data packet's header. Nothing else. So how does the arduino know how big of an buffer to create? also, there is no stop bit being transmitted, so how does it look at a buffer tail? Or is this all created regardless of the transmitter? and then, all the values just get read into the buffer, and then read again from there? Also I don't see a delay in this read method. Wouldn't that cause errors in the data flow? How is that being handled?

So I'm trying to understand a read method. In this method,

// Read data from buffer
int SoftwareSerial::read()
{
if (!isListening())
  return -1;

// Empty buffer?
if (_receive_buffer_head == _receive_buffer_tail)
  return -1;

// Read from "head"
uint8_t d = _receive_buffer[_receive_buffer_head]; // grab next byte
_receive_buffer_head = (_receive_buffer_head + 1) % _SS_MAX_RX_BUFF;
return d;
}

it looks it receives buffer head. But in the write only a 1 or 0 is being sent as the data packet's header. Nothing else. So how does the arduino know how big of an buffer to create? also, there is no stop bit being transmitted, so how does it look at a buffer tail? Or is this all created regardless of the transmitter? and then, all the values just get read into the buffer, and then read again from there? Also I don't see a delay in this read method. Wouldn't that cause errors in the data flow? How is that being handled?

So I'm trying to understand a read method. In this method,

// Read data from buffer
int SoftwareSerial::read()
{
if (!isListening())
  return -1;

// Empty buffer?
if (_receive_buffer_head == _receive_buffer_tail)
  return -1;

// Read from "head"
uint8_t d = _receive_buffer[_receive_buffer_head]; // grab next byte
_receive_buffer_head = (_receive_buffer_head + 1) % _SS_MAX_RX_BUFF;
return d;
}

it looks it receives buffer head. But in the write only a 1 or 0 is being sent as the data packet's header. Nothing else. So how does the arduino know how big of an buffer to create? also, there is no stop bit being transmitted, so how does it look at a buffer tail? Or is this all created regardless of the transmitter? and then, all the values just get read into the buffer, and then read again from there? Also I don't see a delay in this read method. Wouldn't that cause errors in the data flow? How is that being handled?

Source Link
Jonathan
Jonathan
  • 264
  • 3
  • 15

how to create a specific buffer when there is no buffer message in the data packet?

So I'm trying to understand a read method. In this method,

// Read data from buffer
int SoftwareSerial::read()
{
if (!isListening())
  return -1;

// Empty buffer?
if (_receive_buffer_head == _receive_buffer_tail)
  return -1;

// Read from "head"
uint8_t d = _receive_buffer[_receive_buffer_head]; // grab next byte
_receive_buffer_head = (_receive_buffer_head + 1) % _SS_MAX_RX_BUFF;
return d;
}

it looks it receives buffer head. But in the write only a 1 or 0 is being sent as the data packet's header. Nothing else. So how does the arduino know how big of an buffer to create? also, there is no stop bit being transmitted, so how does it look at a buffer tail? Or is this all created regardless of the transmitter? and then, all the values just get read into the buffer, and then read again from there? Also I don't see a delay in this read method. Wouldn't that cause errors in the data flow? How is that being handled?