How many bytes CAN I2C send at a time?
Aryl: So i2c prepares the data to be send by storing it in a buffer (Array), sends it, then the master stores it into its own buffer (Array). And the maximum size of this temporary buffer is 4 bytes, so i2c can only send 4 bytes at a time (A maximum of 4 bytes per wire.write).
How to send strings via I2C between 2 Arduino Nanos?
I have multiple variable length strings which do not exceed 32 bytes each which need to be sent via I2C between 2 Arduino Nanos. I use # to terminate each string. I can successfully send and receive the first string, but for the life of me I can’t figure out how to send the succeeding strings. The samples I am testing with look like this:
What is the buffer length of the Arduino?
The Arduino Wire library has a BUFFER_LENGTH of 32 for both TX and RX. If you call write (buffer, 33) it will return an error. Aryl: So i2c prepares the data to be send by storing it in a buffer (Array), sends it]
Can a wire send a number of bytes?
The Wire.write () can send a number of bytes. The second parameter is the number of bytes. If the second parameter is omitted, only one byte is send, but just one byte is boring… I prefer a struct to create a package and transfer that. Both the Master and the Slave must know the struct of course.
What’s the problem with sending multiple bytes to a slave?
That’s six bytes including the space at the end so everything worked find. The next example is where the master requests 1 byte and the slave responds with one number and everything works as it should. The real problem is when the master requests two or more bytes and the slave sends back that number of bytes when it is not a string.
Can a slave device write to a master device?
It seems like your “slave” devices are trying to write to your “master” as if they were master devices not slaves, and your “master” is rapidly switching between thinking it is one of two slaves. The whole methodology is backwards. The “master” should connect to a “slave” and request the data not wait for a “slave” to randomly throw data at it.