/** Receives a packet from the SL018.
*
* @param length the number of bytes to receive
* @return the number of bytes in the payload, or -1 if bad checksum
*/
byte SL018::receiveData(byte length)
{
// wait until at least 20ms passed since last I2C transmission
while(t > millis());
t = millis() + 20;
// read response
Wire.requestFrom(address, length);
if(Wire.available())
{
// get length of packet
data[0] = Wire.receive();
// get data
for (byte i = 1; i <= data[0]; i++)
{
data[i] = Wire.receive();
}
// show received packet for debugging
if (debug && data[0] > 0 )
{
Serial.print("< ");
printArrayHex(data, data[0] + 1);
Serial.println();
}
// return with length of response
return data[0];
}
return 0;
}
/** Transmit a packet to the SL018.
*/
void SL018::transmitData()
{
// wait until at least 20ms passed since last I2C transmission
while(t > millis());
t = millis() + 20;
// remember which command was sent
cmd = data[1];
// transmit packet with checksum
Wire.beginTransmission(address);
for (int i = 0; i <= data[0]; i++)
{
Wire.send(data[i]);
}
Wire.endTransmission();
// show transmitted packet for debugging
if (debug)
{
Serial.print("> ");
printArrayHex(data, data[0] + 1);
Serial.println();
}
}
/** Receives a packet from the SM130 and verifies the checksum.
*
* @param length the number of bytes to receive
* @return the number of bytes in the payload, or -1 if bad checksum
*/
byte SM130::receiveData(byte length)
{
// wait until at least 20ms passed since last I2C transmission
while(t > millis());
t = millis() + 20;
// read response
Wire.requestFrom(address, length);
byte n = Wire.available();
// get data if available
if(n > 0)
{
for (byte i = 0; i < n;)
{
#if defined(ARDUINO) && ARDUINO >= 100
data[i++] = Wire.read();
#else
data[i++] = Wire.receive();
#endif
}
// show received packet for debugging
if (debug && data[0] > 0 )
{
Serial.print("< ");
printArrayHex(data, n);
Serial.println();
}
// verify checksum if length > 0 and <= SIZE_PAYLOAD
if (data[0] > 0 && data[0] <= SIZE_PAYLOAD)
{
byte i, sum;
for (i = 0, sum = 0; i <= data[0]; i++)
{
sum += data[i];
}
// return with length of response, or -1 if invalid checksum
return sum == data[i] ? data[0] : -1;
}
}
return 0;
}
/** Transmit a packet with checksum to the SM130.
*/
void SM130::transmitData()
{
// wait until at least 20ms passed since last I2C transmission
while(t > millis());
t = millis() + 20;
// init checksum and packet length
byte sum = 0;
byte len = data[0] + 1;
// remember which command was sent
cmd = data[1];
// transmit packet with checksum
//Wire.beginTransmission(address);
for (int i = 0; i < len; i++)
{
#if defined(ARDUINO) && ARDUINO >= 100
Wire.write(data[i]);
#else
Wire.send(data[i]);
#endif
sum += data[i];
}
#if defined(ARDUINO) && ARDUINO >= 100
Wire.write(sum);
#else
Wire.send(sum);
#endif
Wire.endTransmission();
// show transmitted packet for debugging
if (debug)
{
Serial.print("> ");
printArrayHex(data, len);
Serial.print(' ');
printHex(sum);
Serial.println();
}
}
