Introduction
The MC68HC908QL4 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the enhanced M68HC08 central processor unit (CPU08) and are available with a variety of modules, memory sizes and types, and package types.

Features
Features include:
• High-performance M68HC08 CPU core
• Fully upward-compatible object code with M68HC05 Family
• 5-V and 3.3-V operating voltages (VDD)
• 8-MHz internal bus operation at 5 V, 4-MHz at 3.3 V
• Software configurable input clock from either internal or external source
• Trimmable internal oscillator
   – Selectable 1 MHz, 2 MHz, or 3.2MHz or 6.4 MHz internal bus operation
   – 8-bit trim capability
   – Trimmable to approximately 0.4%(1)
   – ± 25% untrimmed
• Software selectable crystal oscillator range, 32–100 kHz, 1–8 MHz, and 8–32 MHz
• Auto wakeup from STOP capability using dedicated internal 32-kHz RC or bus clock source
• On-chip in-application programmable FLASH memory
   – Internal program/erase voltage generation
   – Monitor ROM containing user callable program/erase routines
   – FLASH security(2)
• On-chip random-access memory (RAM)
• Slave LIN interface controller (SLIC) module
   – Full LIN messaging buffering of Identifier and 8 data bytes
   – Automatic baud rate and LIN message frame synchronization:
      No prior programming of bit rate required, 1–20 kbps LIN bus speed operation
      All LIN messages will be received (no message loss due to synchronization process)
      Input clock tolerance as high as ±50%, allowing internal oscillator to remain untrimmed
      Incoming break symbols allowed to be 10 to 20 bit times without message loss
      Supports automatic software trimming of internal oscillator using LIN synchronization data
   – Automatic processing and verification of LIN SYNCH BREAK and SYNCH BYTE
   – Automatic checksum calculation and verification with error reporting
   – Maximum of 2 interrupts per LIN message frame
   – Full LIN error checking and reporting
   – High-speed LIN capability up to 83.33 kbps to 120.00 kbps
   – Switchable UART-like byte transfer mode for processing bytes one at a time without LIN
      message framing constraints
   – Configurable digital receive filter
• 2-channel, 16-bit timer interface module (TIM) with external clock source input
• 6-channel, 10-bit analog-to-digital converter (ADC) with internal bandgap reference channel
   (ADC10)
• 6-bit keyboard interrupt with wakeup feature (KBI)
   – Programmable for rising/falling or high/low level detect
   – Software selectable to use internal or external pullup/pulldown device
• External asynchronous interrupt pin with internal pullup (IRQ)
• Master asynchronous reset pin with internal pullup (RST)
• 13 bidirectional input/output (I/O) lines and one input only:
   – Six shared with keyboard interrupt function
   – Six shared with ADC10
   – Two shared with TIM
   – Two shared with SLIC
   – One shared with reset
   – One input only shared with external interrupt (IRQ)
   – High current sink/source capability
   – Selectable pullups on all ports (pullup/down on port A), selectable on an individual bit basis
   – Three-state ability on all port pins
• Low-voltage inhibit (LVI) module features:
   – Software selectable trip point in CONFIG register
• System protection features:
   – Computer operating properly (COP) watchdog
   – Low-voltage detection with reset
   – Illegal opcode detection with reset
   – Illegal address detection with reset
• Power-on reset
• Memory mapped I/O registers
• Power saving stop and wait modes
• Available packages:
   – 16-pin small outline integrated circuit (SOIC) package
   – 16-pin thin shrink small outline package (TSSOP)

Features of the CPU08 include the following:
• Enhanced HC05 programming model
• Extensive loop control functions
• 16 addressing modes (eight more than the HC05)
• 16-bit index register and stack pointer
• Memory-to-memory data transfers
• Fast 8 × 8 multiply instruction
• Fast 16/8 divide instruction
• Binary-coded decimal (BCD) instructions
• Optimization for controller applications
• Efficient C language support