Brick Labs

Today, while trying to debug the Example 1 from the Experimenters kit, I thought I might be having battery issues.  So I wanted to see what the battery level was.

Being new to RobotC, I figured this might be a fun little mini-project (and I do mean mini) to tackle.

So, first thing I did, was start checking the functions and such in RobotC.  I found a neat value you can read.

nImmediateBatteryLevel

It returns an integer of the battery level.  If your battery level was 7.499, then this value returns 7499.

So I copied a line of code to display this value on the NXT, like this below:

nxtDisplayTextLine(1, "%d", nImmediateBatteryLevel);

Perfect!  But wasn’t quite satisfied.  I wanted to display this on the NXT with the decimal.  And a bit of text so I knew what the value was.

Well, with a bit of math, you can divide a integer by a factor of 10 to get a decimal.  Since I wanted 3 decimal places, I divided by 1000.  In order to do the division, you need to convert (or cast) the integer to a float.  So that’s where the (float) code comes in. I also found you can include plain text in the nxtDisplayTextLine() function, and it will display that.

So here is what I came up with.

nxtDisplayTextLine(1, "Battery: %.3f", (float)nImmediateBatteryLevel / 1000);

That code puts the word "Battery: 7.499" on Line 1 of the NXT screen.  The 7.499 is the actual battery value.  The %.3f means I want a value with 3 decimal places, of type Float.

For those of you with a C background, this is common knowledge.  For those with a Basic background, type conversions are usually automatically done for you.  In RobotC, you have to be explicit about it.