PLLCFG

[mathias_edman]

Hi,

According to the manual of MCP5777C the PLLCFG0, 1 and 2 are all input only signals (Table 3-4. IBE always ON signals (continued)):

PLLCFG02 I 208
PLLCFG12 I 209
PLLCFG2 I 210

But if I look at the system_IO_definition they are listed as:

General Purpose I/O 208

General Purpose I/O 209

General Purpose I/O 210

Can you confirm that PLLCFG 0 and 1 do not have any function for MPC5777C and that they are input only?

/Mathias

[davidtosenovjan]

I would yet add that the fact IBE bit is always ON, does not automatically mean it is input only pin. OBE bit must be just set by software. IBE and OBE bits may be set both, in this case it means it is output pin and its corresponding level is being reflected in the input buffer simultaneously.

[mathias_edman]

Ok, thanks for the clarification.

Mathias

[davidtosenovjan]

Hi, I don't understand you too much. These are just pads with multiple functionalities. May be inputs or outputs. As PLL configuration pins they only works during reset and only if legacy mode is used. There is second option that the configuration is stored in OTP flash area (DCF records).

How to handle configuration pins you may see in the following appnote, sections 5.4 and 5.5:

https://www.nxp.com/docs/en/application-note/AN5268.pdf