ST9+

· Register-Oriented Programming Model
· Single-Space memory addressing
· System and User Stacks
· Interrupt system with fully integrated controller
· Built-in DMA mechanism
· Reset and Clock Control Unit (RCCU) with PLL

In this application, the clock is internal and the input and output pins are unused. The counter is set to continuous mode, and the value of the reload registers chosen so that the overflow occurs exactly every 128 microseconds.