2.2.2 The CLKSEL Fuse can Force PF7 to Remain in UPDI Configuration

When the CLKSEL fuse is configured to OSC32K and a high voltage pulse is applied to the Reset pin, pin PF7 will remain as a UPDI pin even if no UPDI key is given. If PF7 is configured to GPIO pin (UPDIPINCFG is '0' in FUSE.SYSCFG0), it will only return to GPIO mode after a Reset is issued by POR.

Work Around

Do not configure the PF7 pin to the GPIO mode if the CLKSEL fuse is configured to OSC32K.

Affected Silicon Revisions

Rev. A3 Rev. A4
X -