Embedded Files
Introduction
Introduction
Propably the first question that comes to your mind when you read the title that is: What is this? How can be this useful?
The second question is easyer to answer but I will start explaining the first one because you need to understandt it to see the usefullness of this architecture.
what is i2C?
what is i2C?
I2C is a communication protocol that is often used in electronics projects because it only uses two wires for communication and it can be connected to basicaly unlimited devices. The protocol uses a master-multi slave configuration where every slave has an address. The slaves can't comunicate, they can only respond to the masters commands. The master identifies the devices by their address, and uses this address to send a command to a specific device.
What is multi master?
What is multi master?
Multi master is a setup where multiple devices act as masters and both of them give independent command to the slaves while using the same data bus. This configuration is while supported in the I2C specification, it is basicaly never used because it is really sensitive and there aren't any great implementation of it publicly available.
how our setup works?
how our setup works?
In our setup we don't use a multi master configuration that is specified by any specification. We just basically connect the two masters to the same I2C bus. Because of collission issues we implemented communication between the two masters and they tell each other the availability of the bus. On the software side it is preatty simple too. We basicly tell the other master to wait when we do anything with I2C. First we do the configuration of the sensors on both of the masters. In this step it is important that the configuration should be the same, because the second will overwrite the first one int he sensor. After that we read the sensor in the normal way, we check if the bus is available and if available we tell the other master that we are using the busd before reading the data.
Why this is useful?
Why this is useful?
In our project the usecase of this is redundancy. If one of our microcontrollers die the other one can still read the values of the sensors without needing to put another set of the sensors. This reduces weight, prices and complexity in the hardware, but it adds complexity on the software site, to handle the usage of the bus.
Page updated
Google Sites
Report abuse