描述： fm8pb53b : otp device only 42 single word instructions all instructions are single cycle except for program branches which are two-cycle 13-bit wi de instructions all otp area goto instruction all otp area subroutine call instruction 8-bit wide data path 5-level deep hardware stack operating speed: dc-20 mhz clock input dc-100 ns instruction cycle device pins # i/o # otp (word) ram (byte) fm8pb53b 14 12 1k 49 ? direct, indirect addressing modes for data accessing 8-bit real time clock/counter (timer0) with 8-bit programmable prescaler internal power-on reset (por) built-in low voltage detector (lvd) for brown-out reset (bor) power-up reset timer (pwrt) and oscillator start-up timer(ost) on chip watchdog timer (wdt) with internal oscillator for reli able operation and soft-ware watch-dog enable/disable control two i/o ports ioa and iob with i ndependent direction control soft-ware i/o pull-high/pull-down or open-drain control one internal interrupt source: timer0 overflow; two external interrupt source: int pin, port b input change wake-up from sleep by int pin or port b input change power saving sleep mode built-in 8mhz, 4mhz, 1mhz, and 455khz internal rc oscillator programmable code protection selectable oscillator options: - erc: external resistor/capacitor oscillator - hf: high frequency crystal/resonator oscillator - xt: crystal/resonator oscillator - lf: low frequency crystal oscillator - irc: internal resistor/capacitor oscill ator - eric: external resistor/internal capacitor oscillator operating voltage range: 2.0v to 5.5v - ≤4mhz: 2.4v to 5.5v - ≤8mhz: 2.6v to 5.5v, see 6.1 for more information.