I am trying to convert a 3150 design that uses the legacy serial I/O model but on a neuron 5000 device I seem to get 9600baud as opposed to 4800baud so cannot talk to the other proccessor that uses 48baud. What can be the problem? I am using a clock multiplier of 1 for the neuron 5000 device.
The old serial i/o model baud rate scales with input clock. The input clock being the external crystal. For a 3150 neuron the external crystal can only be 10Mhz but that is internally divided to provide a system clock of 5Mhz. For a 3120 device this can be 20Mhz and the baud rate would be 9600.
You need to re-compile the Nodebuilder project for the 5000 device and set the clock multiplier to 0.5. This way you get the same internal system clock as the 3150 device running at 10Mhz. You will then have the baud rate of 4800. Note that you must use Nodeload with the -L and -X options if you load the .ndl file that is generated by Nodebuilder or use the .nme file for programming the serial EEPROM device directly to set the communications parameters correctly.
Note also that the 5000 device is a 3.3v part so level shifters will be required to talk to the other peripheral if it still expecting 5v logic.