Method of operating a microcontroller chip having an internal RC oscillator and microcontroller chip embodying the method
US6925402B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jun 30, 2003 |
| Grant date | Aug 2, 2005 |
| Priority date | — |
| Expiry date | Jun 30, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L1/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A chip includes CPU (12), memories (13,14) for programs and data, peripheral units (18,19) for interacting with the outside world, and an internal RC oscillator (17) for providing clock signals. One of the peripheral units (18) includes a timer counter incremented at a frequency derived from the RC oscillator. The method does not try to change the frequency of the RC oscillator. Instead, an external calibration source (21) is connected to a capture input of the timer unit to provide a signal having a reference frequency, e.g. the mains frequency. The counter is sampled on active edges of that signal, and the sampled values are processed to derive a calibration ratio. After these calibration steps, a software correction is applied to parameters handled by programs stored in memory based on the calibration ratio to compensate for frequency variations of the RC oscillator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.