Special care with the PIC18F2220
During the last run on viperpits a very specific problem with the PIC18F2220 chips used in the daugterboards surfaced.
The chips do not start up after a power on reset and programmed with the current firmware. The reason of this is a hardware change in the chips by microchip. The chips now have a revision id of 6 and in the combination of config switches used in the current firmware this problem occurs.
Microchip offered a workaround for this in the Rev.C silicon errata sheet and this results in setting two config setings different.
In the original firmware these settings are:
CONFIG _CONFIG1H, _IESO_OFF_1H & _FSCM_OFF_1H & _HSPLL_OSC_1H
CONFIG _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L & _BORV_20_2L
If the chip does not start up and the revision number is 6 change this lines to te following:
CONFIG _CONFIG1H, _IESO_ON_1H & _FSCM_OFF_1H & _HSPLL_OSC_1H
CONFIG _CONFIG2L, _PWRT_OFF_2L & _BOR_ON_2L & _BORV_20_2L
A more in depth explanation of this workaround and prepared hex files will be made available on a separate website dedicated to the phcc project.
--Ad Sekeris 18:57, 20 October 2009 (UTC)