Electronics > Projects, Designs, and Technical Stuff
Parallel bus configuration
ricko_uk:
Hi,
I am implementing a one-direction 8-bit bus between a Rasperry Pi and a micro. The Pi is always the master and the data direction is alway only from the Pi to the micro.
Apart from the 8-bit bus lanes I am thinking of using the following signals:
- 8-bit bus lanes
- DATA_AVAILABLE (output from the Pi indicating tot he micro it wants to send data)
- DATA_READ (output from the micro confirming it has read the data)
Is anything missing? Do you think I might need any other signals?
Thank you
madires:
How do you want to implement the bus on the second MCU? Polling the control line DATA_AVAILABLE regularly or interrupt driven?
ricko_uk:
Thank you Madires,
it needs to be as fast as possible so definitely INT driven. Why? Any suggestions or guidelines?
Thank you
madires:
If you use the interrupt driven approach you basically need just a strobe line. For example, the RasPi could set the data bus and pull the strobe line high to indicate that there's data to read. The IRQ on the other MCU is triggered by the strobe and the IRQ handler reads the data bus. Figure out the timing for whole process including safety margins and you'll have a very simple bus protocol.
duak:
I've found it's nice to know from the software & diagnostics side that the destination micro has accepted the data so I wouldn't give up the DATA_READ line. This gives an indirect indication that the micro is working properly.
It can be handy to have a RESET or INIT signal to the micro to put it in a known state.
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