I see different documentation on the Internet about the dsPIC30F family. Especially I am interested in System Configuration registers.

http://ww1.microchip.com/downloads/en/DeviceDoc/70071E.pdf - document from 2008. It lists the following registers:

  • FOSC: Oscillator Configuration Register (Note 2) (0xF80000)
  • FWDT: Watchdog Timer Configuration Register (0xF80002)
  • FBORPOR: BOR and POR Configuration Register (0xF80004)
  • FBS: Boot Segment Configuration Register (0xF80006)
  • FSS: Secure Segment Configuration Register (0xF80008)
  • FGS: General Segment Configuration Register (0xF8000A)
  • FICD: In-Circuit Debugger Configuration Register (0xF8000C)

While another document http://ww1.microchip.com/downloads/en/DeviceDoc/70271b.pdf (from 2009) shows different set of registers:

  • FBS: Boot Code Segment Configuration Register
  • FGS: General Code Segment Configuration Register
  • FOSCSEL: Oscillator Source Selection Register
  • FOSC: Oscillator Selection Configuration Register
  • FWDT: Watchdog Timer Configuration Register
  • FPOR: Power-on Reset Configuration Register
  • FICD: In-Circuit Debugger Configuration Register

The lists themselves and descriptions of the bits (ex the FICD register) differ in significant details.

Both documents do not tell anything about part numbers or silicon revisions they describe.

Does anybody know what doc is better/more accurate? Is there any way to check what config registers are really implemented in the chips that I have in my hands?

  • 1
    \$\begingroup\$ The documents differ significantly, it looks like the later document erases some information and redirects to specific parts to look for details. You probably will be much better off asking this question on Microchip community forums. \$\endgroup\$ Commented Jul 6, 2018 at 0:29

1 Answer 1


The map of configuration registers is not the same on each chip. You apparently found two documents that refer to two different register maps. Note that the family reference manual, for example, has different chapters for different variants of some peripherals. You have to know which variant your particular chip is using.

The right way to determine all these things for any one chip is to look in the datasheet for that chip.

  • \$\begingroup\$ Hi Olin, you comment is too general to bring any value. For example they explain in details (both in family docs and chip specific docs) what devices are present in each chip; FOSC register has versions: V1, V2, V3. And again they explain what version is used where. But on other config registers there is little to no info. \$\endgroup\$ Commented Jul 6, 2018 at 23:18
  • \$\begingroup\$ @Kir: Again, the only definitive source is the datasheet. That may refer to other documents, like specific chapters of the family reference manual. But, you start with the datasheet. \$\endgroup\$ Commented Jul 7, 2018 at 14:25

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