Dec 29

At this moment the only add-on defined is the Primary Motor Cortex, I can imagine there will be more added in a later phase. For this it is important that the software and the electrical design are defined so that more add-ons can be placed in parallel.

Below the impact on the electronics:

  • Address lines, are all inputs. No special action other than that one add-on board should enable the pull-up resistors while the others don’t. If all add-ons would enable the pull-ups they would all be placed in parallel and as such reduce the value (and increase the current consumption).
  • Data lines, all bi-directional but by default set to input. Also here the pull-ups must be enabled on one add-on only.
  • /WR, /RD lines, are all inputs. Again the action on the pull-ups.
  • /INT line, is an input that each add-on can activate. Should be an open collector in that case . In the test software the output is pulled low. Using an open collector circuit would require a transistor, in this case the output on the AT90CAN128 should be inverted. Also a pull-up to the collector input of the transistor would be required, this should only be enabled on one add-on board again using a jumper.
  • /ACK line, is an input that each add-on can activate so same as the /INT line.

Below the impact for the software:

  • Use a define to enable or disable the pull-up on the address, data and control lines.
  • Apply a filter in the read and write ISR’s to see if the command is for that specific add-on.

Leave a Comment

Please note: Comment moderation is enabled and may delay your comment. There is no need to resubmit your comment.