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Hot!Question regarding possible conflict in datasheet PIC16F15344 regarding watchdog registers

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Boxfish
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2020/04/22 06:51:29 (permalink)
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Question regarding possible conflict in datasheet PIC16F15344 regarding watchdog registers

I am referring to the datasheet for the PIC16F15344 - DS40001889B.
 
On page 151. Diagram indicates that the watchdog counter is 5 bits wide.
On page 156. Register 12-5: WDTTMR. Description shows bits 3-6 form part of WDTTMR<3:0>. here the counter register seems to be only 4 bits wide, however on page 157, the summary Table 12-3 shows the relevant register as WDTTMR<4:0> which is 5 bits wide but still only taking 4 bits as bit 7 is greyed out.
 
I looked at the application note for the WWDT - TB3123(DS90003123A) however the register description posted in Table A-1 page 6 also describes the register WDTTMR<4:0> which is 5 bits but also only taking up 4 bit slots with the last one being greyed out.
 
I did not see anything mentioned in the errata.
 
My question is, are the WDTTMR bits the watchdog counter or are they referring to something else? Is the field 4 or 5 bits wide?
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    mbrowning
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    Re: Question regarding possible conflict in datasheet PIC16F15344 regarding watchdog regis 2020/04/22 10:34:54 (permalink)
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    In pic16f15344.h (XC8 2.10) the WDTTMR field is the upper 5 bits of the WDTTMR register.
     
    The WDTPS bits set  prescaler values in increments of 32 (5 bits) so the WDT Tmr is definitely 5 bits.
     
    Although I've seem some strange things in the .h files, I would generally trust them more than the datasheets on this sort of thing. Looks like an error in the datasheet register description. These are all read only bits anyway, and it wouldn't be too hard to test that you can actually read all 5 bits. I wonder if the simulator could be used for this. I never use it, but might be instructive.
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