The Infineon C166S V1 Subsystem is the synthesizable version of the popular C166 16-bit microcontroller plus a rich set of standard peripherals such as general purpose timers and serial ports (synchronous and asynchronous). These tightly integrated peripherals help save power and increase bandwidth by minimizing communication through the external bus interface. The result is a high-performance microcontroller designed for demanding realtime embedded systems applications such as automotive, industrial control, and data communications.

The architecture of the C166S processor combines the benefits of both RISC and CISC (Reduced and Complex Instruction Set Computing). This well-balanced approach delivers the memory saving code density and fast context switching of CISC with the easy RISC instruction decode that enables fast clocking. The C166S processor also features an optional MAC unit to create a unique combination of real-time control and DSP capabilities in one core.

National Semiconductor's CompactRISC architecture was specifically designed for embedded systems and delivers excellent code density, low power consumption, and small die area with the ability to tightly integrate on-chip acceleration, I/O and memory functions. The CompactRISC architecture has firmly established itself by filling a previously unmet need—those applications that require significant embedded performance, but cannot afford the size and cost overhead of full 32-bit RISC implementations. The architecture is enhanced with valuable controller features, like a variable length instruction set and direct bit manipulation, to make it even more effective for embedded applications.

Derived from the successful C166 device family, the C166S V1 Subsystem is fully instruction set compatible with popular Infineon C16x devices and is proven in hundreds of millions of production units.


The C166S V1.2 processor is the foundation of the C166S V1 Subsystem. Features of the C166S V1.2 processor include:

  • 4-state pipelined CPU that is fully compatible with the C166 instruction set
  • Optional support for additional MAC instructions
  • Infineon On-Chip Debug Support (OCDS) and Cerberus communication channel
  • Scalable interrupt controller supporting 12–112 interrupt nodes
  • External Bus Controller that supports the Infineon XBus+ protocol and provides support for the off-chip external bus interface


More than 30 devices have been designed using the C166, leading to a rich ecosystem and making the C166 one of the most robust microcontrollers on the market. Overall, the C166 architecture has a 17% market share in the worldwide 16-bit MCU market. In the automotive market, where the C166 is widely used in power train applications, about 200 million units have been sold. The C166 is also widely used in mobile phones (about 300 million units sold) and in portable media players.


The C166S V1 Subsystem builds upon the C166S V1.2 processor, adding several tightly integrated peripherals:

  • General-purpose timer unit (GPT12E) that includes 5 multifunctional 16-bit timers for timing, event counting, pulse width measurement, pulse generation, and frequency multiplication
  • Asynchronous/synchronous serial channel (ASC) supporting full-duplex asynchronous communication at up to 3.125 MBaud and half-duplex synchronous communication at up to 6.25 MBaud (at 50 MHz)
  • High-speed synchronous serial channel (SSC) supporting fullduplex synchronous communication at up to 25 MBaud in master mode and 12.5 MBaud in slave mode (at 50 MHz)
  • General-purpose I/O ports. These ports can be used as I/O lines (up to 48) or as the external bus for the C166S V1 Subsystem. The C166S external bus is compatible with Infineon’s C166 family of devices.
  • Clock enable generator (CEG), which generates the enable signals for the various submodule clocks


  • Local memory (LM66) bus for single-cycle access to program/ data memory
  • Dual-port RAM interface for access to register banks, stack, and pointers
  • XBus+ for on-chip memories and peripherals
  • PDBus+ for on-chip peripherals and external SFRs
  • External bus/ports interface for off-chip memories and generalpurpose I/O
  • Interrupt input signals
  • Debug interface
  • Clock and reset interface


Development tools for the C166 family are available from several leading tool vendors including:

  • Infineon
  • Altium Limited (TASKING tool suite)
  • Cosmic Systems
  • Keil Software
  • Hitex Development Tools
  • Lauterbach Datentechnik GmbH


Gate count and maximum frequency depend on synthesis tool and target technology. For a typical 90-nm ASIC technology, the complete C166S V1 Subsystem uses approximately 70K (NAND2 equivalent) gates, with a maximum frequency of 125 MHz. The minimum configuration uses approximately 56K gates. The optional MAC unit adds approximately 10K gates.

For FPGA, the C166S V1 Subsystem size is approximately:

  • 7000 slices (Xilinx)
  • 12,000 logic elements (Altera Cyclone II)


  • Synthesizable VHDL source code
  • Integration testbench and tests
  • Documentation
  • Scripts for simulation and synthesis with support for EDA tools