P R O G R A M M E R  20 Device options Memory   Map   ²   &onfigured Memory Size (SX18/28 only). These factory-configured options should not be changed unless you want to reduce the configured amount of program     memory     in     the device. Bor  Trim  ²  Brown  Out  trim bits. These bits allow fine tune of  brownout  level.  Parts  are shipped from factory untrimmed. IR&    Trim    ²    Internal    R& Oscillator trim bits. These bits adjust   the   operation   of   the internal R& oscillator to make it   operate   within   the   target frequency  range  of  4.0  MHz (typical)   plus   or   minus   8%. Parts are shipped from factory untrimmed. To measure current microcontroller frequency, press IR&_FREQ button. Measured internal R& oscillator frequency will be displayed in the status bar. value, program target SX and measure resulting frequency. Oscillator Mode ² This combination of bits sets up the device to operate with a particular type of external oscillator or sets the divide-by factor for generating the instruction clock from the internal oscillator. Eight external oscillator options determined as follows: LP1 ² low-power crystal (32 kHz) LP2 ² low-power crystal/resonator (32 kHz to 1 MHz) XT1 ² low power crystal/resonator (32 kHz to 10 MHz) XT2 ² normal crystal/resonator (1 MHz to 24 MHz) HS1 ² normal crystal/resonator (1 MHz to 50 MHz) HS2 ² normal crystal/resonator (1 MHz to 50 MHz) HS3 ² normal crystal/resonator (1 MHz to 50 MHz) R& ² external R&, OS&2 is pulled high with a weak pullup, no &LKOUT output Four nominal instructions rates with internal oscillator determined as 4 MHz, 1 MHz, 128 kHz and 32 kHz.