**PCB Design Review: TinySparrow, A Module For CAN Hacking, v2**

As a journalist, I'm excited to share my detailed review of the TinySparrow module, designed for CAN hacking. This module has undergone significant improvements since its initial release last year. In this article, we'll dive into the design changes, highlight some notable enhancements, and explore areas where further improvement is possible.

**A Module Redesigned with Feedback**

The new version of the TinySparrow module has taken into account feedback from users and designers alike. Gone are the linear regulator and unprotected CAN transceiver issues of its predecessor. This updated design boasts a new MCU with increased power, ESD diodes for added protection, and improved layout.

**ESD Diode Placement: A Clever Choice**

Upon closer inspection, I noticed that the ESD diodes are placed on the bottom layer, which is an excellent choice. Not only does this minimize the risk of solder bridging during assembly, but it also allows for cost-effective single-side assembly. However, there's a crucial aspect to consider: proper layout around ESD diodes.

While the placement of ESD diodes might seem straightforward at first glance, careful analysis reveals some issues with the current design. The connector tracks are directly connected to CAN ICs on the top layer and ESD diodes on the bottom layer. Ideally, signal routing should pass through the ESD diodes rather than creating a short circuit.

Fortunately, with some minor modifications, we can improve the layout by rerouting 3.3V CAN transceiver power inputs and surrounding signals to accommodate vias under the package. This allows the signal to flow "in series" with ESD diode pads. While it's not perfect, this revised design is an improvement over its predecessor.

**Vias: A Concern Worth Addressing**

As I explored the layout further, I encountered another issue – via placement within component pads. As someone who has had their fair share of via-in-pad related problems, I can attest to the importance of proper vias design.

Using 0402 components can lead to solder paste wicking through the board and onto the opposite side, making assembly challenging. The designer's files hint at using JLCPCB for assembly, which does offer plugged vias as an option. However, this might not be feasible if the board is taken elsewhere, highlighting a need for careful consideration.

**Signal Routing: Room for Improvement**

Upon closer examination of the signal routing, I noticed that vias are indeed placed within component pads. This can lead to issues with solder paste wicking and assembly difficulties. While JLCPCB's design rules accommodate via-to-via distances as low as 0.5mm, it would be beneficial to avoid this altogether.

To mitigate these risks, some signal shuffling could be done to move newly placed vias within the target area. This might require a minor rework of the layout but would pay dividends in terms of assembly reliability.

**GND Pads and Switching Regulator**

One notable improvement is the abundance of GND pins scattered throughout the board. However, I'm surprised by the duplication of the VDC pin on an inner layer. Given that this is supposed to be an unfiltered car power rail, I worry about potential issues with noise integrity.

Moreover, having a key pin (e.g., a pin without any functionality) can help prevent accidental module insertion in the wrong orientation. Thankfully, there's already a NC pin present; it would be beneficial to consider relocating this to avoid potential short-circuits when the module is rotated 180 degrees.

**A Module with Much Promise**

The TinySparrow v2 has undoubtedly improved significantly since its initial release. The updated design takes into account user feedback and incorporates new components, such as ESD diodes and a more powerful MCU. While there are areas for improvement, this module has made significant strides in terms of layout and signal routing.

**Conclusion**

In conclusion, the TinySparrow v2 is an exciting development in CAN hacking modules. Its improved design, added protection features, and increased power make it an attractive option for designers looking to create custom ECUs. With a few tweaks to address via placement and signal routing, this module has the potential to become even more reliable.

If you're interested in getting your board reviewed or would like to submit a tip, please do so by sending a message with [design review] in the title, linking to your board files (KiCad preferred).