I am trying to use the PLL mode on an 18F252 but turning on that option in the config does not change the speed of the PIC at all. My config options are as follows uisng BoostC... #pragma DATA _CONFIG1H, _OSCS_OFF_1H & _HS_OSC_1H & _HSPLL_OSC_1H #pragma DATA _CONFIG2L, _BOR_ON_2L & _BORV_20_2L & _PWRT_OFF_2L #pragma DATA _CONFIG2H, _WDT_OFF_2H & _WDTPS_128_2H #pragma DATA _CONFIG3H, _CCP2MX_ON_3H #pragma DATA _CONFIG4L, _STVR_ON_4L & _LVP_OFF_4L & _DEBUG_OFF_4L #pragma DATA _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L & _CP2_OFF_5L & _CP3_OFF_5L #pragma DATA _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H #pragma DATA _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L & _WRT2_OFF_6L & _WRT3_OFF_6L #pragma DATA _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H & _WRTD_OFF_6H #pragma DATA _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L & _EBTR2_OFF_7L & _EBTR3_OFF_7L #pragma DATA _CONFIG7H, _EBTRB_OFF_7H I tried a 10MHz and 4MHz ceramic resonator with built in caps. Any ideas? Thanks! -- Ian Smith -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist