I am planning to buy an esc for my tricopter setup. What is the purpose of programming an esc? I am cost effective .and is it really necessary that I should necessarily buy a programming card to program my esc for my model? help plzzz...
You should know that there is "programming" and "flashing".
Programming is setting some values to change the behaviour of the ESC. For example you can modify the low voltage cutoff level if you are using other batteries than LiPos, etc. That can be done using a programming card that is usually brand specific to the ESC. But as far as I know most ESCs can be programmed using the transmitter too. Usually you have to push the throttle all the way up before connecting the battery. Then you will get different kinds of beeps that require you to move the trottle up or down.
That's a little tedious, but works and you should not need to change it that often
Flashing on the other hand is putting a new firmware on the ESC processor. This usually needs to be done for multirotors where the stock "fixed wing" programming is too slow to have a stable flight. It requires special tools like an "USBasp AVR" to connect to your PC and quite often an "Atmel Atmega Socket Firmware Flashing Tool" that helps connecting the right pins on the chip to the USBasp device.