Interacting With Nets

Nets act as named interfaces to your instruments. After you configure your Nets, the Lager Client controls those instruments. Use either the CLI or the Python SDK. The examples below show how to command the common instrument types. These include power supplies, battery simulators, debuggers, and communication buses.

Setting Defaults

First, set default values for --box and for common nets. Defaults keep you from repeating them on every command:

# Set a default box so you don't need --box on every command
lager defaults add --box my-lager-box

# Set default nets for common instrument types
lager defaults add --supply-net POWER
lager defaults add --debug-net DEBUG_NET
lager defaults add --i2c-net I2C_0

With defaults set, you can run commands more concisely (e.g., lager supply voltage 3.3 instead of lager supply POWER voltage 3.3 --box my-lager-box). See the defaults reference for all options.

CLI Examples

Supply Nets

Power supply Nets can be controlled using the lager supply command. Set voltage and protection thresholds (note: this does not enable output):

lager supply POWER voltage 5 --ovp 5.1 --ocp 0.5 --box my-lager-box

OVP (Over-Voltage Protection) and OCP (Over-Current Protection) are safety thresholds. If the output voltage or current exceeds these limits, the supply automatically shuts off to protect your device. You can clear a tripped fault with lager supply POWER clear-ovp or clear-ocp.

Enable the output:

lager supply POWER enable --box my-lager-box

Disable the output:

lager supply POWER disable --box my-lager-box

Battery Nets

Some programmable power supplies support battery simulation. These can be controlled using the lager battery command. Set the simulated battery’s state of charge (SOC):

lager battery BATT soc 50 --box my-lager-box

SOC (State of Charge) is the battery’s charge level as a percentage, from 0 to 100. An SOC of 50 simulates a half-charged battery. Use it to test how your device behaves at each battery level.

Set max charge and discharge current:

lager battery BATT current-limit 1.0 --box my-lager-box

Debug Nets

Debugger nets (e.g. J-Link) can be used to flash firmware, erase memory, and inspect devices. Flash a hex file to your device:

lager debug DEBUG_NET flash --hex firmware.hex --box my-lager-box

Where DEBUG_NET is the name of your debug net. You can also use a default debug net if configured.

I2C and SPI Nets

For communicating with peripheral devices over I2C or SPI buses:

# Scan the I2C bus for connected devices
lager i2c I2C_0 scan --box my-lager-box

# Read 2 bytes from register 0x00 on device at address 0x76
lager i2c I2C_0 transfer 2 --address 0x76 --data 0x00 --box my-lager-box

# Read a SPI device ID (send 0x9F command, read 3 response bytes)
lager spi SPI_0 transfer --data 0x9f 4 --box my-lager-box

Programmatic Control with Python

The Lager Python SDK performs the same operations in code. Use it for more complex automation, or to integrate with a test framework. The following example shows how to write a Python script using the Net API:

Create a Python script. Save the following code to a file named flash.py:

from lager import Net, NetType

# Get a debug net by name
dbg = Net.get('DEBUG_NET', type=NetType.Debug)

# Reset and flash the firmware
dbg.reset(halt=True)
dbg.flash('path/to/firmware.hex')

print("Firmware flashing complete.")

Execute the script with Lager. Use the lager python command. It runs the script in the Lager Box environment, where the script can reach the connected hardware.
lager python flash.py --box my-lager-box

For detailed Python API documentation, see the Python Reference section.

For a more comprehensive example combining power supply control, firmware flashing, ADC measurement, and safe cleanup, see the demo script.

Next Steps

You’ve completed the Getting Started guide. Here’s where to go from here:

Your First Test — Walk through a complete end-to-end test workflow
CLI Reference — Full documentation for all CLI commands
Python API — Automate tests with the Python SDK
Defaults Reference — Reduce typing by setting default box and net values
Troubleshooting — Solutions for common issues

​Setting Defaults

​CLI Examples

​Supply Nets

​Battery Nets

​Debug Nets

​I2C and SPI Nets

​Programmatic Control with Python

​Next Steps

Setting Defaults

CLI Examples

Supply Nets

Battery Nets

Debug Nets

I2C and SPI Nets

Programmatic Control with Python

Next Steps