With the 16.6-2015 Allegro PCB Editor release, the Snake pattern router can be enabled from the context menu of the Add Connect command. This functionality provides the ability to route through hex pattern packages utilizing arc routing, which has been greatly improved compared to the existing prototype pattern generator. Simply enable Snake mode via the RMB and Add Connect will detect a hex pattern pin/via field and dynamically convert to arc routing:
Read on for more details …
Snake Mode and Options
The Snake functionality is available in the RMB context menu after selecting a net for routing using Add Connect. Once in Snake mode the bubble options under the Option window will be automatically disabled as the route will be dynamically weaved through the hex pattern as you move your cursor through the pin/via field. Selecting a point outside of the pin/via will convert back to standard line mode to continue routing and convert to arc routing once re-entering the pin/via field. This will allow easy transition from arc to non-arc routing when voids exist in the pin pattern:
• RMB – Snake options – Center Single Traces in Channel
This option setting will automatically center the route in the center of the channel and as you move through the channel, it will dynamically show what the resulting route will look like. Clicking with the LMB will accept the pattern as you see it:
• RMB – Snake options – Switch Single Trace to other Lane
When the Center Single Traces in Channel is not enabled, you have the ability to switch between the nearest or farthest channel for dynamic routing using Switch Single Trace to other Lane:
Routing behavior during Add Connect
Once Snake mode is enabled, Add Connect will detect a hex pattern pin/via field and automatically switch over to arc routing, allowing two single routes or differential pair routing in the channel. Starting a single connection will default to the nearest channel, reserving space for an additional trace in the opposite channel using the default same net spacing. As you move your cursor through the pin/via field, it will dynamically show the resulting trace.
Route a single trace in nearest channel:
LMB Select the opposite channel and route a single trace in the farthest channel:
Indicating in a direction will dynamically show the expected route path:
LMB Select to guide the dynamic route in the route direction:
NOTE: LMB Select outside of the hex pattern package pin field will convert back to normal (non-arc) routing, and re-entering the pin field will convert back to arc routing with Snake mode enabled.
Limitations
• Single route, two routes, or a single differential pair route will be equally spaced in between the pins/vias in the channel. If the constraints do not allow two between routing, you will see traces dynamically highlight, indicating that a DRC error condition exists and an LMB Select to commit the dynamic routes will result in DRCs.
• Bubble and Smooth options are disabled when Snake mode is enabled.
• Routing in an offset channel (single trace) and switching to a center channel route using RMB – Snake options – Center Single Traces in Channel will produce a 90-degree corner at the transition. Improved transition is expected in 17.2.
• Snake pattern routing will be disabled once an LMB Select is made outside of the pin field and convert back to Snake pattern upon entering the pin field again. To get a predictable bubble result outside of the hex pattern package, we recommend disabling Snake mode.
Some performance impacts have been seen when the routed cline contains a large amount of arc segments or when excessive arc weaving is done inside of the hex pattern package.
Looking forward to your input!
Jerry "GenPart" Grzenia