Solved

how do I remove the MSB of a value before concatenating it with another?

Posted on 2012-03-16
2
386 Views
Last Modified: 2012-03-16
I am writing to two 7-segment LEDs and each of them are controlled with seven bits. I have each digit I want to display stored as a byte. I need to write the high and low digit values as a concatenation to the 7-segment LEDs.  This is a problem because the MSB of the low digit will become the LSB of the high digit. For example, if I am writing the value 99 to the 7-segment LEDs, "0011000" needs to be written to each 7-segment LED.  But because the values are stored as bytes, "00011000" will be the output value for 9, and the concatentation of 9 and 9 would be 00011000 00011000, and "0110000 0011000" will be written to the LEDs instead of "0011000 0011000". How do I get rid of the low digit MSB before concatenating??
0
Comment
Question by:frostyourself
2 Comments
 
LVL 16

Accepted Solution

by:
HooKooDooKu earned 500 total points
ID: 37731964
WORD DoubleDigit;
BYTE LowDigit;
BYTE HighDigit;
... /* set your value for the two digits */
DoubleDigit = (WORD) HighDigit << 8 + (WORD) LowDigit << 1;
DoubleDigit = DoubleDigit >> 1;

Open in new window


Basically, shift the high digit to the 2nd byte, then shift the low digit once.  Then shift both together to the right one.

Now I might have your digits transposed here (i.e. you might need to swap HighDigit with LowDigit). but the idea is still the same.  Utilize the << and >> bit shift operators.  You can first utilize the bit shift on a single byte, then concatenate the two bytes (placing one in the high order byte of a 16-bit word) and then bit shift the whole 16-bit value to get the final value you need for the LED display.
0
 

Author Closing Comment

by:frostyourself
ID: 37731989
Thank you!
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
NotAlone Challenge 20 79
data scientists and AI 17 102
firstChar challenge 13 110
Not seen Link button 5 15
Have you thought about creating an iPhone application (app), but didn't even know where to get started? Here's how: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Important pre-programming comments: I’ve never tri…
When we want to run, execute or repeat a statement multiple times, a loop is necessary. This article covers the two types of loops in Python: the while loop and the for loop.
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

920 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now