Week 2
Research how current can be measured
2 ways:
Older way: Shunt Resistor
- What is a shunt resistor
- how does it work
- why is it the older method
Newer way: Magnetic Sensing using Hall effect sensors or ct’s
- what is Hall effect sensor and how does it work
- how does the current transformer work
- why is it the newer method
Considerations for both:
- can they both measure AC and DC current
- which one is easier to understand (for teaching and documentation purposes)
- which one is easier to implement
- is one method cheaper or more accurate
- what are the disadvantages and advantages
Reference meter used INA219AIDR IC
- which method does this IC use to measure the current
- is this the best IC to use for the meter
- can it do both dc and ac current
Concerns:
How will whatever current measured be communicated and end up on display
Week 3
I was able to form an understanding of measuring current using a shunt resistor and researched the INA219AIDR IC. I need to continue forming an understanding of hall effect sensors to make a more informed opinion on which method would be best to use.
To Do:
Newer way: Magnetic Sensing using Hall effect sensors or ct’s
- why is it the newer method
Considerations for both:
- which one is easier to implement
- what are the disadvantages and advantages
Concerns:
How will whatever current measured be communicated and end up on display
Week 4 update
I made some good progress in understanding the INA219. I created a schematic and the shunt resistor circuit, in the datasheet they provided the optional implementation of an input filter circuit that I will consider adding to the schematic if necessary. I continued researching how to program the IC for different max expected currents and shunt resistances. Programming an ic is new to me especially using C++, but there is a good library on Arduino that I found. I will continue creating pseudo code necessary for the program if I include that library.
To-do list-
Get a final shunt resistance value. This will depend on how confident I feel that I can change the default shunt resistance the IC uses. After that is determined document the resolution of the current being measured and the range. By determining this I will build documentation of how the IC actually converts the current internally and how the code does so using current_LSB, PGA, etc.
My biggest Concern:
is actually making code that will compile. I feel confident that I can create code that should work but should I run into an issue, a minute detail I miss, I fear I would not be able to figure out why.
Week 5 update:
Finalized current sensing details and determined LCD screen with i2c adapted would be best for displaying measurements.
To list:
Research how i2c adapter module should be connected to LCD screen
transmissible or transflective LCD
how will the combination be added to the final board
research code for displaying the measurements (find library)
understand the implementation of code create pseudo code