TMS320F280039C: TMS320F280039C

Hello Nirojan,

There will be a slight delay in responses since the expert for this device is out of office.

Many thanks,

Opus

Hi,

Nirojan Navaratnarajah said:

I have connected a TMS320F280039C to a TMS320F28388D using jumper wires for the CLK, Data 0, and Data 01 lines (for FSI) and have connected both grounds of docking stations to each other directly to provide common ground configuration.

You're using two ControlCARDs + docking station for each board? Using the smaller pitch FSI header on the ControlCARDs themselves could be better than the HSEC DOCK pins (i.e. shorter trace from header to C2000 device). You should de-populate some resistors to disconnect the signals to the HSEC connector if you use the headers.

Nirojan Navaratnarajah said:

I am wondering if this issue is occurring because I am not using the adapter board, or if there could be any other reasons for this. Has anyone tested the transmission at higher frequencies by connecting the pins as I have done? Could the adapter board be necessary for reliable transmission at frequencies above 30MHz?

It's possible signal integrity requirements are not being met and the adapter board would help with that.

Best,

Kevin

Hi,

I recently did some testing with FSI communication between a TMS320F280039C and a TMS320F28388D.

Pay attention to the different specifications. The FSI can be operated with max. 60 MHz on the TMS320F280039C. The TMS320F28388D however is only specified up to 50 MHz.

You can check these specifications in the data sheets of the devices:

TMS320F28388D: SPRSP14E, Pages 202 (TX) and 205 (RX)
TMS320F280039C: SPRSP61A, Pages 186 (TX) and 189 (RX)

It is really important to create a low impedance current return path at higher frequencies. Maybe you can try a different wiring with twisted pairs of wires. I would recommend using three pairs for FSICLK, FSID0 and FSID1, each twisted with a ground wire. The reduced area between the wires reduces the interaction with electromagnetic fields. Carrying a ground wire in a twisted pair creates a low impedance loop for the current.

Best regards,

Stefan

Hi Stefan,

Stefan Schiffer1 said:

Pay attention to the different specifications. The FSI can be operated with max. 60 MHz on the TMS320F280039C. The TMS320F28388D however is only specified up to 50 MHz.

Yes, F28003x device was spec'd for 60MHz since it's a 120MHz device (divide by 2 to generate clock).

Were you able to get higher communication speeds to work in your new tests with improved cabling? Differential devices + twisted pair are ideal for longer communication lengths and offers improved noise immunity compared to single-ended signals.

Best,

Kevin