Utility to collect power measurements.
Certain boards have shunt resistors on them to measure current on key voltage rails. On many such TI development boards, an INA226 is usually mounted on a seperate i2c bus to allow external tools to measure current, voltage etc.
This is useful, but it is a pain to get the tools to work consistently. They are either built for windows OR expensive etc.. Instead, as developer with access to other development platforms, it is very very trivial to use the 2nd development platform's i2c bus to read power numbers from the board that is under evaluation.
Doing things in userspace and linux is so much easier and allows us to do additional processing that pre-packaged utilities dont let us.
So, that was basically the history of what motivated this simple utility.
NOTE: There are more than one way to skin a cat :). Solutions like http://www.totalphase.com/products/aardvark-i2cspi/ do exist in the market which may do this job as well and may even be incorporated in this tool similar to the support of FTDI MPSSE option added.
- It can measure current and voltage and do averaging (if that is what you'd like it to do) and many other things that I wont put in README.md and keep it updated :D.
- It uses configuration file to read information about the measurement environment. So, adding support for a new board you want to measure is a new config file.
- It runs on Linux - but I think any posix OS might work. Tested only on v3.15.
- It currently runs as a sandbox(test) on any linux box - PC or anywhere.
- It currently runs as measurement build on beaglebone-black (but no reason why it would be restricted there)
Option 1: use a development board (example beaglebone black)
(*)ptool runs here
BeagleBone Black(*)
o +-------+ uart +------------------+
-+- | | cable | |
| +> | +----------> +------------------+
+ | | +------------------+ P9 expansion connector
/ \ +-------+ | |
PC | I2C |
You serial +-+----+ |
:) utility | |----------+
(minicom) +----------------+--------------------+
| | | |
| | | +-------------+ |
| | | | | |
| | | | Sink for | |
| | | | Supply | |
| | | +------+------+ |
| | | | |
| v v +----------> | - |
| | | |
| +---------+ +-----+-----+ |
| | INA226 | | Shunt | |
| | | | Resistor | |
| +---------+ +-----+-----+ |
| | | |
| +----------> | + |
| | |
| +-------+------+ |
| | Source of | |
| | Supply | |
| +--------------+ |
| |
+-------------------------------------+
Board under measurement
Option 2: use an FT2232H Mini Module[1] http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_FT2232H_Mini_Module.pdf
(*)ptool runs here
FT2232H Mini Module
o +-------+ USB +------------------+
+ | | cable | |
/|\ +> | +----------> +------------------+
+ | | +------------------+ CN2/CN3 connector
/ \ +-------+ | |
PC | I2C |
You Terminal(*) +-+----+ |
:) | |----------+
+----------------+--------------------+
| | | |
| | | +-------------+ |
| | | | | |
| | | | Sink for | |
| | | | Supply | |
| | | +------+------+ |
| | | | |
| v v +----------> | - |
| | | |
| +---------+ +-----+-----+ |
| | INA226 | | Shunt | |
| | | | Resistor | |
| +---------+ +-----+-----+ |
| | | |
| +----------> | + |
| | |
| +-------+------+ |
| | Source of | |
| | Supply | |
| +--------------+ |
| |
+-------------------------------------+
Board under measurement
ptool is a utility that you run on beaglebone black / PC and use it to measure the current and voltage on another platform. It uses i2c-dev to talk to the INA226 ADC, collect current and voltage values and finally displays it to user.
In reality, you can run it anywhere and as long as you have an ADC, an shunt mounted on the actual board, you can measure.
You can invoke ptool in any way you like: over serial port, ethernet or what ever.
If your board only has shunt resistor and no INA226, then look for one of those off the shelf INA226 devel boards.
-
Cross Compiling: It is pretty much similar to kernel
make CROSS_COMPILE=arm-linux-gnueabi-
-
Native build:
make
-
Building a sandbox (testing without actually wanting to do measurements on real board). There may be many reasons you'd like this: you dont have a board and want to give powertool features a feel; you'd like to write an enhacement to powertool and want to run valgrind or debug with gdb that your final platform wont let you.. etc.. basically sandbox is pretty much powertool except it generates random data instead of actual measurement
make ARCH=sandbox
-
Building with mpsse (FTDI bitbang example) - requires libftdi and libftdi-dev installed:
make I2C=mpsse
At the end of the build, you get 'ptool'
What else can make do? just run: make help
Umm.... really? Since the tool keeps changing on my whim (and soon, hopefully, your whim), I dont really want to keep this document updated. Instead, the following should get you started.
./ptool -?
As of this writing (current revision 0.1), this is how it looks like:
├── configs - place where all board config files are
├── docs - details on connections and misc stuff
├── include - general includes
├── kernel-patches - uggh.. should be empty, but, at times..
├── lib - third party libraries are organized in directories
│ ├── i2c-tools
│ │ ├── include
│ │ │ └── linux
│ │ └── tools
│ ├── lcfg
│ └── omapconf
│ └── common
└── src - everything source
└── powertool - here we are.. and start at main.c
if you add new tools, we'd have it here.
I like C over python, C++, java.. ruby.... etc..
For using this tool as it is, setup is simple: Beaglebone - i2c - INA on board (or seperate board) - shunt resistor on voltage rail. Follow the wiring as described in docs/board_details.txt for each of the supported boards that have configs/ config file.
It cant get easier than this:
busName = {
/*
* BeagleBoneBlack Bus mapping - Should not change if you wire it right.
* if changed, then change this mapping
*/
i2c = "1"
rail_name = {
/* This represents 1 INA meauring a specific voltage rail */
group = "measurement group"
address = "INA's i2c address in hex"
input = "What is the input to the shunt (the + side of INA measurement)"
output = "What is the output of the shunt (the - side of INA measurement)"
shunt_value = "What is the shunt resistor value used in Ohms"
shunt_accuracy = "How accurate is the resistor in %"
}
}
Folks who work on newer linux kernel will notice the similarity of this with device tree. Yeah, you are right.. I should probably start calling it ABI and write bindings document :P.. (poking-fun-at-device-tree, which happens to be a running joke among we kernel folks in 2014)
Jokes apart, the logic is pretty similar to device tree, but not exactly the same though - no ';' seperator, no phandles... but should be rather self evident when you look at existing examples.
Using mpsse, build with I2C=mpsse and use a configuration like the following: busName = { /* * When using a FT2232H Mini Module over MPSSE interface * Format: vendorID:productID:interface:serialNumber * use lsusb -v to see the details */ i2c = "0x0403:0x6010:2:FTVFS9V0"
rail_name = {
/* This represents 1 INA meauring a specific voltage rail */
group = "measurement group"
address = "INA's i2c address in hex"
input = "What is the input to the shunt (the + side of INA measurement)"
output = "What is the output of the shunt (the - side of INA measurement)"
shunt_value = "What is the shunt resistor value used in Ohms"
shunt_accuracy = "How accurate is the resistor in %"
}
}
See configs/example_ftdi.conf for detailed example
https://github.com/nmenon/powertool
Yes! If you are reading this section, I am happy! :). I wrote this tool in around a couple of days. It is no close to being complete. You can:
- Download and give it a shot - even sandbox version
- Read code and provide fixes - even grammatical or spelling fixes are nice to get.
- Support your own environment world - new board config files are nice.
- See the hard things in TODO which I never got around to doing, help fix them up
- Write new features that you might like it to do.. NOTE: lets not make it powertop replacement.
What ever you want to do, do it :). and send me github pull requests once you are done and feel like it. Just remember to check out LICENSING for your contributions, I'd like to continue to keep it GPLV2.
There is no mailing lists at the moment, no IRC channels either. But, I usually lurk around in a few channels on freenode.net, so feel free to ping me if you need.
You are kidding, right? I want to make it clear: This is just a personal itch I scratched. I might even not think about this tool anymore a few years down the line.
If using this tool or resultant data or in any modified version, you kill someone, get sued, blow up a board/home/city/country/, triggered a nuke, started an inter galactic war, lost your job, got elected as your country's president or became bankrupt, loose business, something nasty, or anything I have'nt listed here,.... I do NOT take any responsibility for either me or my employer. Touch it or it's generated data at your own risk.
Repeat: This is NOT a tool written as an "official" software delivery from either me or my employer. This is NOT supported in any form, style or fashion or any official form.
If you'd like something like that.. Check out the market, if you shell out enough $$$ you can find enough tools for that.
If you are ok with the above and still wanna help.. check out the 'How to contribute' section.
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