PIC16(L)F18446 PWRTS Config Bits Errata Clarification

[Dabbot]

A clarification on the PIC16(L)F18446 PWRTS Config Bits errata found here:
https://ww1.microchip.com/downloads/en/DeviceDoc/PIC16(L)F18426-46-Family-Silicon-Errata-and-Data-Sheet-Clarification-80000799C.pdf

The Power-up Timer Selection bits, PWRTS[1:0] in Config Word 2 @ 0x8008, allow you to select a power up delay before code execution begins:
11 PWRT disabled
10 PWRT set at 64 ms
01 PWRT set at 16 ms
00 PWRT set at 1 ms

Errata item 1.6.1 states:

Bit 2 of PWRTS<1:0> in the CONFIG2 register is not functional. This bit is the upper bit of the Power-Up Timer Selection bits, PWRTS<1:0>. This means that the functions selected by PWRTS = 11 and PWRTS = 10 are not available.

The errata item states the following work around:

The other functions selected by PWRTS = 01 and PWRTS = 00 are available

But what you actually encounter is Bit 2 is stuck set, which means you can only choose PWRTS = 10 (64 ms) or PWRTS = 11 (disabled). Functionally, I have tested the startup delay is correct for both settings.

Additionally, if you choose PWRTS = 00 (1 ms) or PWRTS = 01 (16 ms), you get an error upon programming verification caused by Bit 2 being stuck set:

Code: [Select]

configuration memory
Address: 8008 Expected Value: 3ee0 Received Value: 3ee4
Failed to program device

Just leaving this here in case anyone else encounters the problem.

[amyk]

So the errata have errata? I'm not surprised, but still...

[Dabbot]

So the errata have errata? I'm not surprised, but still...

It's as if the person writing the errata was told "Bit 2 in CONFIG2 register doesn't work," and they were left to figure out what that meant, but didn't test to properly characterize the issue.

[jpanhalt]

In that person's defense, most non-functioning bits are read as 0.  Nevertheless, anyone in my lab would have checked.