A bit of confusing text but I interpret it as the internal oscillator circuit for an external crystal does not work. An external crystal oscillator circuit must be used in order to use a crystal. So a crystal resonator alone can't be used (2 pins) but a crystal oscillator (4 pins) can. /Ruben On Sun, 20 Aug 2017 11:33:10 +0200, Electron wrote: > Hi! > on the errata of the PIC32MZ EF FAMILY for the A1 revision I can read: >=20 > 2. Module: Oscillator > Revision A1 Silicon: > A crystal oscillator cannot be used as an input to the Primary Oscillator > (POSC) pins OSC1 and OSC2. > Revision A1 Silicon Work around: > Use an external clock or the Internal FRC Oscillator. >=20 > Is it right to understand that in A1 revisions a Xtal cannot be used? >=20 > This is a serious and unexpected bug, no doubt. I have plenty of A1's.. := -( >=20 > Cheers (not really), > Mario --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .