Short: Frequency meter for AURA equipped amigas Author: scaprile@geocities.com Uploader: scaprile geocities com Type: util/misc Architecture: m68k-amigaos Hi everybody ! This code is a quick hack, I just happened to need a frequency counter and so I wrote it. Feel free to use it, modify it, and send it back to me ;) C sources included. The directory "loop" contains a CPU-hog version, allowing for higher frequency measures. Just click "GO" and it starts, press the left mouse button and it returns control back to you. The "int" directory contains an interrupt driven version, which is highly affected in accuracy by system load, but lets you run it while still using your machine. This program uses part of CIA_interval.c code, provided on the RKRM Devices manual. The operating principle is easy, I just set up a 1 sec window and count zero crosses of the incoming signal, then divide by two and display. The 1 sec window is calculated as an approximation. A sample rate is defined, then the CIA divisor to get this rate is calculated. As it often is not an integer number, then the real sample rate is calculated by doing E/(this number). This is quite often also a fractional number, so this is a source of inaccuracy, as the total number of samples in a 1 sec window won't be an integer. The E clock frequency is taken from SysBase, so this could be another source of inaccuracy. As I said before, this is a quick hack and I didn't pay much attention to accuracy, it shows a 5-10 % accuracy and it works for me. If you write a better code, please send it. ------------------------------------------------ AMIGA | Sergio R. Caprile, Bs. As., Argentina | // | email: scaprile@geocities.com | \X/ | DSP, Music, Electronics, Tai Chi Chuan | ------------------------------------------------ http://www.geocities.com/CapeCanaveral/Lab/2885| ------------------------------------------------