SPI COMMUNICATION BETWEEN PIC'S WITH SAFETY SOFTWARE

Hi,

We're developing a new circuit to control ignition and flame of the water heater burner. that means MCUs' software has to fulfil 60730 Class C safety software requirements.

We're using

- PIC16F946 as Safety controller and SPI communication master.

- PIC16F77 as Safety monitor/supervisor and SPI communication slave.

both MCUs share information about the safety field sensors and its own status in order to shut down gas valve case of any default detection or misunderstood between MCUs

In order to warrant reliability and safety in communication and to avoid collisions, some "guru"s propose to add a signal from the slave to the master MCU to notify when it is ready to send/receive a 8- bit-packet.

Do you agree that solution? any other proposal?

Does Anyone know bibliography about this topic?

Thanks in advance....

Former Member over 13 years ago

Hi,

If you want to avoid collisions, I use this method:
1) You send your data
2) You read your data at the same time that you send them.
3) If your receibed data is different from your sended data, there was a collision. You need to wait a random time and try again.

Is a good idea to add same checksum data
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