Cannot connect to MCF52xx through BDM

[wyu]

   Hi everyone! This is my first time on the forum, so please bear with me.

I am doing this senior design project for my school, and we are using MCF5213CAF80. Our customer has a prototype that works, and we are supposed to work and improve upon it. We have two PCB design, one is basically identical to our customer's original version, and another is much more condensed. After getting the PCB made from www.4pcb.com, we assembled both boards. On the one that is identical to the original prototype, we were able to communicate with the MCU from PC through P&E's ColdFire Multilink; however, we cannot do the same with the more condensed version.

We checked all the connections, and they are in the correct order. We probed the crystal with the osciloscope, and there was a clear clock running. All the signals on the BDM header are connected correctly, and they show the right voltage. However, codewarrior simply does not connect to the MCU.

I double checked all the connections, and the only discrepancy I have with the prototype is a 0 ohm resistor. I took it out in my version, because I don't think it does anything. However, on the other board the 0 ohm was there, and we could talk to the MCU with that one.

If anyone has any insights on this, I would really appreciate it. Thank you very much!

[TomE]

Assuming Nick's suggestion doesn't fix your problem (and help explain it)...

> the only discrepancy I have with the prototype is a 0 ohm resistor. I took it out in my version,

> because I don't think it does anything. However, on the other board the 0 ohm was there,

> and we could talk to the MCU with that one.

So patch up your board to have the same connection that zero ohm resistor provides and see if that fixes the problem. Of course if it connects to a CPU pin in a BGA package that you didn't connect a track to it becomes a bit harder to do this, but not impossible.

Since you didn't provide any schematic or reference or even pin or network name, I have no idea what that zero ohm resistor connects to. If you provide some details I can check the Reference Manual and see if the lack of that resistor explains your problem.

Tom

[foreigner]

Hi,

I had a similar problem on one of our boards with a MCF5211.

It was fixed by slowing down the debugger (USB Multilink) communication.

1. Open the Settings window in Codewarrior.

2. Click on "Remote Debugging" under "Debugger".

3. Click on "Edit Connection".  You will get a warning, just click OK.

4. Change the USB port speed to 5.

That's how my problem got fixed.

Nick