SBL2E Chip custom board

[gdolson]

I have built a board around the SBL2E Chip that is simply an Ethernet to single Serial Port board. I am trying to troubleshoot it and was wondering if there was any documentation to show what the minimum connections are on the controller to get it to boot properly. I basically used the SBL2E board schematic as a model.

Thanks,
Greg

[rnixon]

Why not just use the NetBurner board? Exactly what is different than the NetBurner design? I would start there, since if it was identical it seems like there would not be any problem.

The freescale processor manual for that device should have the minimum connections. I would guess power, gnd, clk, reset in, large enough power supply etc. Take a look at the reset out and clock out and see if they are correct. For example, rst out should not be toggling.

[gdolson]

Well, I figured it out. There are some lines that the SBL2E firmware requires to run, that they don't mention in any of their documentation. In fact there is no documentation on how to build a board around the SBL2E chip at all. The lines that I had to add are: /RCON (pin 3) to +3V, TEST (pin 38) and JTAG_EN (pin 12) to GND, /BKPT (pin 2) and DSCLK (pin 6) to +3V through 4.7kohm resistors. Hope this helps someone else.

[rnixon]

There are so many variations it can be difficult. I think if there is any deviation from any reference design I would recommend looking the the Freescale processor manual to determine if they are necessary or not for any particular design. I've had problems before because app notes and docs that copy information from the chip manufacturers documentation can get out of date due to errata.

[pbreed]

The pins you describe are all required to force the processor into boot mode and set the configuration.
Its not for the netburner firmware, its the freescale chip hardware.

[gdolson]

Thanks pbreed, that makes sense. I have noticed that it works without the DSCLK line pulled high. Should I pull that up anyway?

[pbreed]

DSLK can be high or low, it just should not be floating.
If you are not ever using the BDM interface it can be tied high or low.