JS220 Beta

The JS220 Beta program started in early October 2022 to a select group of customers and reviewers.  This page serves as the starting resource for our beta customers.

The beta program hardware consisted of both the Joulescope JS220 (JS220-K000-001) and the JS220 Evaluation Kit 1 (JS220-EVK1-001).  These two things will be separate, orderable products.  The JS220 is our next-generation measurement instrument that improves upon the JS110.  The EVK1 allows you to quickly get starting with the JS220 measuring real-world signals.  You can also get starting by connecting the JS220 to your own real-world system.

Links

• Download the Joulescope UI
• JS220 User's Guide
• JS220 Evaluation Kit 1 info
• Comparison with JS110
• GitHub repos
• joulescope_driver - New C user-space driver
• pyjoulescope - Existing python driver with joulescope_driver adapter
• pyjoulescope_ui
• pyjoulescope_examples
• jls - The latest v2 joulescope file format
• js220_end_panels - Open-source JS220 hardware end panels
• Support: Forum and support@joulescope.com
• Compliance

 

Known issues

We are still working on the Joulescope JS220 software support, including the new native driver.  You may encounter a number of known issues while using your JS220 beta device.  We are actively working to fix these issues.  If you notice any issue, please email support @ joulescope.com.  Thank you for your help and understanding as we work to make a great, high-quality product!

Hardware Changes

 The JS220 production units fix a couple of hardware issues with the beta units:

1. The beta units do not meet the USB inrush specification.  We mistakenly pulled up the sensor subsystem active-low enable to the control-side 3.3V supply.  Unfortunately, this 3.3V supply is delayed relative to the +5V that supplies the sensor subsystem.  While this particular enable does not actually activate the sensor, it does expose a very significant amount of capacitance to the USB host for about 10 milliseconds.   This capacitance is protected by a current limiter so the host should easily be able to handle the capacitance, but it does violate the USB spec.  This will be fixed for the production units.
2. The guaranteed minimum voltage measurement range is limited to ±13.6 V.  Production units will be ±14.5 with ±14.7 typical.

Joulescope User Interface (UI)

1. The following features are deprecated and no longer change behavior:
1. Device rescan_interval
2. The JS220 ignores the following features:
1. Voltage Range (v_range)
2. sampling_frequency
3. ext_io voltage (uses fixed internal 3.3V reference, external reference not selectable through UI yet)
4. Device on_close
3. The UI does not yet support streaming of gpi2, gpi3, and trigger in.

Device

1. USB Suspend is ignored.  The JS220 consumes full power even when requested to suspend, which violates the USB spec's 2.5 mA max suspend current.
2. Sample ids do not account for internal delays.  Data from different processing paths may be unaligned.

Planned features not yet implemented

1. UTC time sync
2. On-instrument downsampling
3. Soft-fuse
4. Triggering
5. UART RX & TX support