Important changes to forums and questions
All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.
11 years, 11 months ago.
m3pi battery voltage lcd display
Can someone help this old beginner get an example going that displays the battery voltage constantly?
My goal is to tie it to a digital relay that automatically turns the attached battery charger on/off.
Thanks
Bo
2 Answers
11 years, 11 months ago.
Chris,
Thanks a lot for the example program!! I studied it line for line and think I understand it (with my very limited knowledge so far). However, the 3pi battery voltage STILL ELUDES ME. Only the second line of your example displays. I can replace the current_volts in the printf statement to a number such as 3.14 and it displays OK.
I have learned how to put the LED on/off lines in my programs to help debug, to get an idea how far the program gets before choking. Thanks for that idea.
(I'm really an assy lang lover, using a JTAG to single step thru a program to see what I'm doing.) :)
I'll work with it some more tomorrow. If I can get this elusive voltage display to work then I'll feel better and can move onward. :)
Thanks again.
Bo (P.S. I'd sure like to hear from the MBED/3pi folks, it seems they are scarce.)
11 years, 11 months ago.
Hi Bo,
The m3pi library has an API function which returns the current battery voltage as a float.
The full API documentation can be found at :
Your application code can periodically call the battery methodss and choose what to do as a result, i.e. switch the charger on/off as needed.
I don't have an m3pi to hand so its not tested, but this might be a suitable framework to adapt.
Chris,
Thanks a lot for the example program!! I studied it line for line and think I understand it (with my very limited knowledge so far). However, the 3pi battery voltage STILL ELUDES ME. Only the second line of your example displays. I can replace the current_volts in the printf statement to a number such as 3.14 and it displays OK.
I have learned how to put the LED on/off lines in my programs to help debug, to get an idea how far the program gets before choking. Thanks for that idea.
(I'm really an assy lang lover, using a JTAG to single step thru a program to see what I'm doing.) :)
I'll work with it some more tomorrow. If I can get this elusive voltage display to work then I'll feel better and can move onward. :)
Thanks again.
Bo (P.S. I'd sure like to hear from the MBED/3pi folks, it seems they are scarce.)
posted by 20 Jan 2013