1.1 S3F8 Series Microcontrollers
Zilog’s S3 Family of 8-bit single-chip CMOS microcontrollers offers a fast and efficient CPU, a wide range of
integrated peripherals, and various mask-programmable Read only memory (ROM) sizes. Address/data bus
architecture and a large number of bit-configurable Input/Output (I/O) ports provide a flexible programming
environment for applications with varied memory and I/O requirements. It includes timer/counters with
selectable operating modes to support real-time operations.
1.2 S3F8S39/S3F8S35 Microcontrollers
The S3F8S39/S3F8S35 single-chip CMOS microcontrollers are fabricated using the highly advanced CMOS
process technology based on Zilog's latest CPU architecture. The S3F8S39/S3F8S35 is a microcontroller with
an embedded 32K/16K byte full-flash ROM.
By using a proven modular design approach, Zilog engineers have successfully developed the
S3F8S39/S3F8S35 by integrating these peripheral modules with the powerful SAM8 RC core:
• Four configurable I/O ports (26 pin)
• Twenty six interrupt sources and eight interrupt levels
• Eight bit-programmable pins for external interrupts
• One watchdog timer function (Basic Timer)
• One 8-bit basic timer for oscillation stabilization
• Two 8-bit timer/counters and three 16-bit timer/counters with selectable operating modes
• A Stop Wake-Up Timer to wake up CPU from Stop Mode
• Watch timer for real time
• Two asynchronous UART modules
• One SPI module
• One IIC module
• Analog to digital converter with 16 input channels and 10-bit resolution
• One BUZ for programmable frequency output

1.3 Features
1.3.1 CPU
• SAM8RC CPU core
1.3.2 Memory
Features of internal multi-time program Full-Flash memory are:
− 32K  8-bit program memory (S3F8S39)
− 16K  8-bit program memory (S3F8S35)
o Sector size: 128 Bytes
o User programmable by "LDC" instruction
o Sector erase available
o Fast programming time
o External serial programming support
o Endurance: 10,000 erase/program cycles
o 10 Years data retention
• Data Memory (RAM)
− 1,040 × 8 bit data memory
1.3.3 Instruction Set
• Seventy eight instructions
• Idle and Stop instructions
1.3.4 26 I/O Pins
• Twenty six normal I/O pins for 32 pin
1.3.5 Interrupts
• Eight interrupt levels and 26 interrupt sources
• Fast interrupt processing feature
1.3.6 Timers and Timer/Counters
• One programmable 8-bit Basic Timer (BT) for oscillation stabilization control or watchdog timer function.
• One 8-bit timer/counter (Timer A) with three operating modes:
− Interval Mode
− Capture Mode
− PWM Mode