FSCAL1 on CC2520

I'm new to the CC2520 and I am configuring the registers as specified in "Table 21: Registers that need update from their default value" of the SWR068 December 2007 datasheet.  In all but the case of the FSCAL1 register when I write to the register with MEMWR I can see that the reset value is as specified in the datasheet and when I read it back to verify I can see it is set to the value I had written.  In the case of the FSCAL1 register, the initial value is 0x01 not the 0x29 reset value specified and when I write the 0x2B and read it back I get 0x03 not 0x2B.  The function used for each register is the same.

It is unclear to me what the difference is with FSCAL1 since the datasheet doesn't have any useful information on this register since it states that this is one of the registers that generally shouldn't be accessed.

I would appreciate any insight into this matter.

Thanks.

The FSCAL1 register does not read back what was written. Bits 0 and 1 are read as written, but the others bits may vary. Thus, reading back 0x03 is normal when you wrote 0x2B.

Thank you.  Are there any other registers that behave this way, aside from the FSCAL registers?

I had same difficulty.Thanks Kelly for posting this problem and thanks hec for your reply.