PSoC4: UltraSonic Sensor based Distance Measurement

Hi Shaunak,

are you facing a problem with the display, the formatting of the result or the values you compute?

Which hardware does the project run on?

Some comments:

It is always advisable to have a main loop running at a constant frequency instead of a loop that is governed by external hardware. In this case: the smaller the distance, the faster the loop will run. To avoid this and to shorten software, use a PWM that generates a 10µs pulse at the desired frequency of 40Hz, trigger the sensor with that pulse, clear/load the timer and so on.

Your documentation is very good, although I didn't find (maybe overlooked) the underlying hardware specs (board: Kit or custom)

Your program structure may be better using an initialization part, a sensor handler, a display handler and a handler for calculating distance. For more accuracy: Largest error influence comes from temperature, wikipedia helds a formula for that and the chip has got a raw measurement capability. Especially in your country where environment temps are comparably high the difference betweein conditioned inside and on the street may be remarkable.

Bob

Anything on the LCD? Is the "Distance =" showing? -> Hardware issue.

else

There is some peculiar about "print float in PSoC4", have a keyword search (at top of this page) for that and take the newer infos from Robyn.

Bob

You must enable the nano library to get the sprintf() working -

http://www.cypress.com/?id=4&rID=87354 newlib-nano

Regards, Dana.

I am using the Creator 3.2 early access and there is in the project settings an item to enable float formatting. This option costs you 14kB of flash. If that is too much, you may find some libraries using quite less program memory. Alternatively convert the float yourself by converting the fractional part separately as integer with the required precision

Intpart = (uint)MyFloat;

FracPart = (uint)((MyFloat-Intpart)*1000);

sprintf(Buffer,"%d.%d",Intpart,FracPart);

Will give your MyFloat converted with 3 decimal places. You must care for the sign separately.

Bob

You are always welcome, Shaunak!

Bob

I posted a minor update to project in PSOC 3 forum,

eg. a delay to allow sensor to start up. Seems to

be working fine with or without delay as original project

did not have.

Attached pin chart for Pioneer board in case you need it.

Regards, Dana.

If you want to avoide sprintf( ) altogether -

http://stackoverflow.com/questions/2302969/how-to-implement-char-ftoafloat-num-without-sprintf-library-function-i

Not sure of its general capability or limitations.

Regards, Dana.