http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2008 Rickey's World contact@nospam.com (Ajay Bhargav) contact@nospam.com (Ajay Bhargav) Thu, 08 Jan 2009 23:14:09 -0800 Thu, 08 Jan 2009 23:14:09 -0800 http://backend.userland.com/rss e107 (http://e107.org) 60 Search 8051 Microcontroller Projects AVR PIC Projects Tutorials Ebooks Libraries codes query http://www.8051projects.net/search.php http://www.8051projects.net/forum-t11246.html
i am making a Freq.meter/counter using 8051, i have no problem in coding and the methodology but i am stuck at the thought of Max freq. that can be measured by 8051.

i know the limitation of F/24 ( crystal freq divided by 24) i am using 12 Mhz crystal and that would give me 500 Khz max freq limit. with 24Mhz Crystal the max freq. is 1 Mhz

but the Timer in counter mode or in timer mode can only count up to 65,536D (FFFFH) after which it gets reset, so how is it possible to count 500 KHz or 1Mhz.

i am using a gate interval of 1 Sec with timer1.


i hope you folks can clear my confusion]]> Wed, 30 Jul 2008 10:49:02 -0700 http://www.8051projects.net/forum-t11246.html http://www.8051projects.net/forum-t11246.html use the corresponding timer/counter overflow interrupt to increment a software counter by one each time the counter overflows. this will be ur MSB and the THX/TLX will be ur LSB. So, even if u increment a single bytein the service routine, the combination will count upto FFFFFFH which is more than sufficient for ur application.

P.S. : do not worry about losing any input pulse counts while u are incrementing the MSB in the overflow interrupt as the internal counter will continue counting even when ur service routine is being executed and will only stop when u disable it by changing the TMOD/TCON registers.]]> contact@nospam.com (Ajay Bhargav) Wed, 30 Jul 2008 20:14:42 -0700 http://www.8051projects.net/forum-t11246.html http://www.8051projects.net/forum-t11246.html Thank you pdi33,

in my timer0 ISR ( set as counter) if the count reaches FFFF, i am reseting TL0 & TH0 to 00h ( i know it automatically resets to 00H).

but you are advising to INC a 8 bit register or a variable for each time the counter overflows. so total maximum count would be FF of 8 bit register and FFFF of 16 bit couner/timer.


so i need a 3 byte hex to BCD conversion routine


thanks for your suggestion
]]> contact@nospam.com (Ajay Bhargav) Wed, 30 Jul 2008 23:44:55 -0700 http://www.8051projects.net/forum-t11246.html