Hi, Just wondering if you could help me. I'm trying to generate a meduim freq squarewave atan op port on the 8051 using keil tools. I can generate it for a certain time using an 8bit timer and decrementing a register to get a duration of the transmit 'pulse'. I'm just wondering if anyone has done something similar and if they could tell me how to initiate a tmer or counter (whichever is best to use) when I send out this pulse and how to stop the same timer/counter when I receive it at my analog input on the chip. The time between the start and stop of the timer would then be operated on to determin a distance based on speed = dist/time. its for a project i'm having trpouble with a the moment. its an ultrasonic distance measurement device.

If anyone has any ideas could you post em here and I will check back. code for this would be excellent indeed. cheers Daire