diff options
Diffstat (limited to 'firmware/libs-device/osccal.h')
| -rw-r--r-- | firmware/libs-device/osccal.h | 34 |
1 files changed, 13 insertions, 21 deletions
diff --git a/firmware/libs-device/osccal.h b/firmware/libs-device/osccal.h index 710ce05..af37a43 100644 --- a/firmware/libs-device/osccal.h +++ b/firmware/libs-device/osccal.h @@ -1,10 +1,10 @@ /* Name: osccal.h * Author: Christian Starkjohann * Creation Date: 2008-04-10 + * Changes 2013-11-04 cpldcpu@gmail.com * Tabsize: 4 * Copyright: (c) 2008 by OBJECTIVE DEVELOPMENT Software GmbH * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt) - * This Revision: $Id: osccal.h 762 2009-08-12 17:10:30Z cs $ */ /* @@ -14,30 +14,18 @@ oscillator so that the CPU runs at F_CPU (F_CPU is a macro which must be defined when the module is compiled, best passed in the compiler command line). The time reference is the USB frame clock of 1 kHz available immediately after a USB RESET condition. Timing is done by counting CPU -cycles, so all interrupts must be disabled while the calibration runs. For -low level timing measurements, usbMeasureFrameLength() is called. This -function must be enabled in usbconfig.h by defining -USB_CFG_HAVE_MEASURE_FRAME_LENGTH to 1. It is recommended to call -calibrateOscillator() from the reset hook in usbconfig.h: -*/ +cycles, so all interrupts must be disabled while the calibration runs. +The size optimized assembler implementation includes its own implementation +of usbMeasureFrameLength. Therefore USB_CFG_HAVE_MEASURE_FRAME_LENGTH should +be set to 0 to avoid including unused code sections. It is recommended to call +calibrateOscillatorASM() from the reset hook in usbconfig.h by including osccal.h: -#ifndef __ASSEMBLER__ -#include <avr/interrupt.h> // for sei() -extern void calibrateOscillator(void); -#endif -#define USB_RESET_HOOK(resetStarts) if(!resetStarts){cli(); calibrateOscillator(); sei();} +#include "osccal.h" -/* This routine is an alternative to the continuous synchronization described in osctune.h. -Algorithm used: -calibrateOscillator() first does a binary search in the OSCCAL register for -the best matching oscillator frequency. Then it does a next neighbor search -to find the value with the lowest clock rate deviation. It is guaranteed to -find the best match among neighboring values, but for version 5 oscillators -(which have a discontinuous relationship between OSCCAL and frequency) a -better match might be available in another OSCCAL region. +Algorithm used: See osccalASM.x Limitations: This calibration algorithm may try OSCCAL values of up to 192 even if the @@ -53,7 +41,11 @@ deviation! All other frequency modules require at least 0.2% precision. #ifndef __OSCCAL_H_INCLUDED__ #define __OSCCAL_H_INCLUDED__ -//void calibrateOscillator(void); +#ifndef __ASSEMBLER__ + void calibrateOscillatorASM(void); +# define USB_RESET_HOOK(resetStarts) if(!resetStarts){ calibrateOscillatorASM();} +# define USB_CFG_HAVE_MEASURE_FRAME_LENGTH 0 +#endif /* This function calibrates the RC oscillator so that the CPU runs at F_CPU. * It MUST be called immediately after the end of a USB RESET condition! * Disable all interrupts during the call! |