Dec 21

Before designing the add-on board of the primary motor cortex I will first connect the ATDVK90CAN1 board to the FOXBoard in order to verify if the defined parallel interface will work using the selected pins. Below image shows how the interface signal are mapped over the two expension connectors J6 and J7.

On the ATDVK90CAN1 board there are also two 20 pins headers that holds most of the IO pins of the AT90CAN128. Since most pins are also used for other functions on this board it is important to first remove a lost of jumpers and solder shorts. Also the power supply is 3V or 5V while the FB is running at 3V3.

Below the insructions how to modify the ATDVK90CAN1 board:

  • Cut away the rectifier U6, this will create a virtual ground level when both the FB and the ATDVK90CAN1 board are powered using the same power supply.
  • On the backside, patch the + and the – as shown on below image. NOTE: this will set the plus of the power supply to the inner center of the power plug and the minus the the outher body of the power plug. This is OPPOSITE than the power cable that is supplied with the kit. I only do this so since all my projects use the center as the plus and prevent mistakes.
  • Solder a 68E resistor parallel to R14. As a result, the 5V is reduced to 3V3. This voltage can be measured over C19 which is the big yellow capacitor just above switch SW3.

  • Set and remove the jumpers so it matches below image. Also verify the positions of the switches.

  • Cut the below red colered solder strips on the back side of the board:

  • Solder two 2×20 header strips on the bottom side of the board in the footprint of J13 and J14. For this the rubber feets must be removed, I just moved them over a bit to other emty spaces.

For the cable assembly itself, take 1 times 20cm and 1 time 30 cm of 40 pins flatcable for example from a IDE interface cable. On one side, assemble a 40 pins header, this part will be placed on the headerstrip on the ATDVK90CAN1 board. Cut all wires loose and cut away the non-used wires based on this schematic. Please note that since J13 and J14 are soldered on the back of the PCB the pin 1 marking on the headers is no longer valid!

On the other side, strip the wires and solder them to two 2×20 headerstrips that will be inserted in the headers of the FB. I also used some shrinktube to isolate each wire, it happended too many times aready that a test setup caused many problems with shorts or open wires after a couple of days. The amount of time that than must be spend to find the problem is by far more than now used for making a good assembly.

The final assembly should look somthing like below. Do not connect it yet to the FOXBoard, first two pieces of software need to be developed: for the AT90CAN128 and for the FOXBoard.

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