extra/usb_power/powerlog.README.md

# Sweetberry USB power monitoring

This tool allows high speed monitoring of power rails via a special USB
endpoint. Currently this is implemented for the Sweetberry board.

To use on a board, you'll need two config files, one describing the board, a
`.board` file, and one describing the particular rails you want to monitor in
this session, a `.scenario` file.

## Converting from servo_ina configs

-   Method 1 (not limited to chroot)

    Many configs can be found for the servo_ina_board in `hdctools/servo/data/`.
    Sweetberry is plug compatible with servo_ina headers, and config files can
    be converted with the following tool:

    ```
    ./convert_servo_ina.py <board>_r0_loc.py
    ```

    This will generate `<board>_r0_loc.board` and `<board>_r0_loc.scenario`
    locally, which can be used with `powerlog.py`.

-   Method 2 (recommended for Chrome OS developers, requires chroot)

    If you are using `powerlog.py` within the chroot, copy `<board>_r0_loc.py`
    to `src/third_party/hdctools/servo/data`, then add this line to file:

    ```python
    config_type = 'sweetberry'
    ```

    And run command in chroot:

    ```
    (Anywhere in chroot, just ONCE) cros_workon --host start dev-util/hdctools
    ```

    Then every time you make a change to `<board>_r0_loc.py`, run:

    ```
    (Anywhere in chroot) sudo emerge dev-util/hdctools
    ```

    The command will install the corresponding `.board` and `.scenario` file in
    the chroot. To use `powerlog.py` use the command:

    ```
    (Anywhere in chroot) sudo powerlog -b <board>_r0_loc.board -c <board>_r0_loc.scenario
    ```

    There is no need to specify the absolute path to the `.board` and
    `.scenario` file, once they are installed into the chroot. If there is any
    changes to `<board>_r0_loc.py`, you need to `sudo emerge dev-util/hdctools`
    again.

## Board files

Board files contain a list of rails, supporting 48 channels each on up to two
Sweetberries. For each rail you must specify a name, sense resistor value, and
channel number. You can optionally list expected voltage and net name. The
format is as follows, in json:

example.board:

```json
[
{ "name": "railname",
  "rs": <sense resistor value in ohms>,
  "sweetberry": <"A" for main Sweetberry, "B" for a secondary Sweetberry>,
  "channel": <0-47 according to board schematic>,
  "v": <optional expected bus voltage in volts>,
  "net": <optional schematic net name>
},
{...}
]
```

## Scenario files

Scenario files contain the set of rails to monitor in this session. The file
format is simply a list of rail names from the board file.

Optionally, you can specify the type of measurement, from the set of `"POWER"`,
`"BUSV"`, `"CURRENT"`, `"SHUNTV"`. If not specified, the default is power.

example.scenario:

```json
[
"railname",
"another_railname",
["railname", "BUSV"],
["railname", "CURRENT"],
...
]
```

## Output

`powerlog.py` will output a csv formatted log to stdout, at timing intervals
specified on the command line. Currently values below `-t 10000` do not work
reliably but further updates should allow faster updating.

An example run of:

```
./powerlog.py -b board/marlin/marlin.board -c board/marlin/marlin_short.scenario -t 100000
```

Will result in: `ts:32976us, VBAT uW, VDD_MEM uW, VDD_CORE uW, VDD_GFX uW,
VDD_1V8_PANEL uW 0.033004, 12207.03, 4882.81, 9155.27, 2441.41, 0.00 0.066008,
12207.03, 3662.11, 9155.27, 2441.41, 0.00 0.099012, 12207.03, 3662.11, 9155.27,
2441.41, 0.00 ...`

The output format is as follows:

-   `ts:32976us`

    Timestamps either zero based or synced to system clock, in seconds. The
    column header indicates the selected sampling interval. Since the INA231 has
    specific hardware defines sampling options, this will be the closest
    supported option lower than the requested `-t` value on the command line.

-   `VBAT uW`

    Microwatt reading from this rail, generated on the INA by integrating the
    voltage/amperage on the sense resistor over the sampling time, and
    multiplying by the sampled bus voltage.

-   `... uW`

    Further microwatt entry columns for each rail specified in your scenario
    file.

-   `... xX`

    Measurement in uW, mW, mV, uA, uV as per config.

## Calculate stats and store data and stats

When appropriate flag is set, powerlog.py is capable of calculating statistics
and storing statistics and raw data.

-   Example 1

    ```
    ./powerlog.py -b board/eve_dvt2_loc/eve_dvt2_loc.board -c board/eve_dvt2_loc/eve_dvt2_loc.scenario --save_stats [<directory>]
    ```

    If `<directory>` is specified, this will save stats as:
    `<directory>/sweetberry<timestamp>/summary.txt`. If `<directory>` does not
    exist, it will be created.

    If `<directory>` is not specified but the flag is set, this will save stats
    under the directory which `powerlog.py` is in: `<directory of
    powerlog.py>/sweetberry<timestamp>/summary.txt`.

    If `--save_stats` flag is not set, stats will not be saved.

-   Example 2

    ```
    ./powerlog.py -b board/eve_dvt2_loc/eve_dvt2_loc.board -c board/eve_dvt2_loc/eve_dvt2_loc.scenario --save_raw_data [<directory>]
    ```

    If `<directory>` is specified, this will save raw data in:
    `<directory>/sweetberry<timestamp>/raw_data/`. If `<directory>` does not
    exist, it will be created.

    If `<directory>` is not specified but the flag is set, this will save raw
    data under the directory which `powerlog.py` is in: `<directory of
    powerlog.py>/sweetberry<timestamp>/raw_data/`.

    If `--save_raw_data` flag is not set, raw data will not be saved.

-   Example 3:

    ```
    ./powerlog.py -b board/eve_dvt2_loc/eve_dvt2_loc.board -c board/eve_dvt2_loc/eve_dvt2_loc.scenario --save_stats_json [<directory>]
    ```

    If `<directory>` is specified, this will save MEANS in json as:
    `<directory>/sweetberry<timestamp>/summary.json`. If `<directory>` does not
    exist, it will be created.

    If `<directory>` is not specified but the flag is set, this will save MEANS
    in json under the directory which `powerlog.py` is in: `<directory of
    powerlog.py>/sweetberry<timestamp>/summary.json`.

    If `--save_stats` flag is not set, stats will not be saved.

    `--save_stats_json` is designed for `power_telemetry_logger` for easy
    reading and writing.

## Making developer changes to `powerlog.py`

`powerlog.py` is installed in chroot, and the developer can import `powerlog` or
use `powerlog` directly anywhere within chroot. Anytime the developer makes a
change to `powerlog.py`, the developer needs to re-install `powerlog.py` so that
anything that imports `powerlog` does not break. The following is how the
developer installs `powerlog.py` during development.

Run command in chroot:

```
(Anywhere in chroot, just ONCE) cros_workon --host start chromeos-base/ec-devutils
(Anywhere in chroot, every time powerlog.py is changed) sudo emerge chromeos-base/ec-devutils
```