Evening all,
Just published this to my profile:
http://mbed.org/users/go2dev/programs/SRF02_lib/lqjp2t
A work in progress library for a simple SRF02 ultra sonic range finder module (I2C interface).
If you take a look through my code, you will see it is possible to import the library and then request a measurement in one of three formats.
I don't want to publish it as a library properly just yet though as
- Its not documented
- I think it could be made more efficient (code space).
Basically, I had to copy the main chunk of code three times and change a single variable which seems really wasteful. I'm new to the C++ party and all the things I tried won't compile properly.
Instead of
float SRF02::distancecm(){
//local variables
const char m_addr = 0xE0; //srf02 default slave address
char commandsequence[2];
// Get range data from SRF02 in cm
// Send Tx burst command over I2C bus
commandsequence[0] = 0x00; // Command register
commandsequence[1] = 0x51; // Ranging results in cm
m_i2c.write(m_addr, commandsequence, 2); // Request ranging from sensor
wait(0.07); // Average wait time for sonar pulse and processing
// Read back range over I2C bus
commandsequence[0] = 0x02; //
m_i2c.write(m_addr, commandsequence, 1, 1); //
m_i2c.read(m_addr, commandsequence, 2); // Read two-byte echo result
//combine upper and lower bytes in to a single value
float range = ((commandsequence[0] << 8) + commandsequence[1]);
return range;
}
repeated a bunch of times for each measurement type, I think what I want is something like:
float SRF02::measurecm{
float result = dosonar(0x51);
return result;
}
float SRF02::measureblah{
float result = dosonar(whatever);
return result;
}
float SRF02::dosonar(char rangetype){
//local variables
const char m_addr = 0xE0; //srf02 default slave address
char commandsequence[2];
// Get range data from SRF02 in cm
// Send Tx burst command over I2C bus
commandsequence[0] = 0x00; // Command register
commandsequence[1] = rangetype; // Ranging results type
m_i2c.write(m_addr, commandsequence, 2); // Request ranging from sensor
wait(0.07); // Average wait time for sonar pulse and processing
// Read back range over I2C bus
commandsequence[0] = 0x02; //
m_i2c.write(m_addr, commandsequence, 1, 1); //
m_i2c.read(m_addr, commandsequence, 2); // Read two-byte echo result
//combine upper and lower bytes in to a single value
float range = ((commandsequence[0] << 8) + commandsequence[1]);
return range;
}
I don't know enough about C++ to know what the correct conventions for this sort of thing is, I have an idea about what should be public and what should be private but I'd like some advice or tips from those more experienced so I don't spend for ever going round in circles only to do it the "wrong" way (many ways to skin a cat, I know but some are more sensible than others).
Any advice much appreciated
Cheers
D
Evening all,
Just published this to my profile: http://mbed.org/users/go2dev/programs/SRF02_lib/lqjp2t
A work in progress library for a simple SRF02 ultra sonic range finder module (I2C interface).
If you take a look through my code, you will see it is possible to import the library and then request a measurement in one of three formats.
I don't want to publish it as a library properly just yet though as
Basically, I had to copy the main chunk of code three times and change a single variable which seems really wasteful. I'm new to the C++ party and all the things I tried won't compile properly.
Instead of
float SRF02::distancecm(){ //local variables const char m_addr = 0xE0; //srf02 default slave address char commandsequence[2]; // Get range data from SRF02 in cm // Send Tx burst command over I2C bus commandsequence[0] = 0x00; // Command register commandsequence[1] = 0x51; // Ranging results in cm m_i2c.write(m_addr, commandsequence, 2); // Request ranging from sensor wait(0.07); // Average wait time for sonar pulse and processing // Read back range over I2C bus commandsequence[0] = 0x02; // m_i2c.write(m_addr, commandsequence, 1, 1); // m_i2c.read(m_addr, commandsequence, 2); // Read two-byte echo result //combine upper and lower bytes in to a single value float range = ((commandsequence[0] << 8) + commandsequence[1]); return range; }repeated a bunch of times for each measurement type, I think what I want is something like:
float SRF02::measurecm{ float result = dosonar(0x51); return result; } float SRF02::measureblah{ float result = dosonar(whatever); return result; } float SRF02::dosonar(char rangetype){ //local variables const char m_addr = 0xE0; //srf02 default slave address char commandsequence[2]; // Get range data from SRF02 in cm // Send Tx burst command over I2C bus commandsequence[0] = 0x00; // Command register commandsequence[1] = rangetype; // Ranging results type m_i2c.write(m_addr, commandsequence, 2); // Request ranging from sensor wait(0.07); // Average wait time for sonar pulse and processing // Read back range over I2C bus commandsequence[0] = 0x02; // m_i2c.write(m_addr, commandsequence, 1, 1); // m_i2c.read(m_addr, commandsequence, 2); // Read two-byte echo result //combine upper and lower bytes in to a single value float range = ((commandsequence[0] << 8) + commandsequence[1]); return range; }I don't know enough about C++ to know what the correct conventions for this sort of thing is, I have an idea about what should be public and what should be private but I'd like some advice or tips from those more experienced so I don't spend for ever going round in circles only to do it the "wrong" way (many ways to skin a cat, I know but some are more sensible than others).
Any advice much appreciated Cheers D