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 2008-12-01T22:56:33-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t10253.html 2008-12-01T22:56:33-08:00 i want to make a speed and distence meter for a boat by using microcontroller.a speed signal is generated by a sensor which has the frequency equals to the 10 times of engine shaft ratation. eg if engine shaft is rotating 60 times in a second then sesor gives the signal of 600 Hz. sensor also generate a refresh pulse in a second with pulse width of 0.33 sec.the question is that how to programme the microcontroller for counts these pulses. thanks http://www.8051projects.net/forum-t10253.html 2008-12-01T22:56:33-08:00 pdi33 use the internal counter of the 89c51. here u have to just input the pulses from the speed sensor (assuming they are at +5V level) to the T0 pin of the uC. Check the TMOD and TCON registers of the 89c51 in its datasheet for the description of how to use the internal timers of 8051 in counter mode.If the refresh pulse u mentioned is another output of the sensor, then connect that input to the external interrupt of the 89c51 so that it can be processed in the respective interrupt service routine. http://www.8051projects.net/forum-t10253.html 2008-12-01T22:56:33-08:00 grace hello can anybody help me find a book regarding mobile robotics.. http://www.8051projects.net/forum-t10253.html 2008-12-01T22:56:33-08:00 pdi33 hi grace,please stick to the subject of the thread. Post ur doubt on a new thread in the appropriate section of the forum.here is a link to the appropriate place for ur doubt:(e-books & tutorials section)http://www.8051projects.net/forum18.html