tEDAx - back annotation

version info

There is a new version of this block, v2, available.

purpose

In many workflows the ultimate source of information is the schematics. However, in later phases of the design there can be changes, for example GPIO pins or slots of multi-slot swapped, footprint changed because of PCB layout constraints.

The back annotation block communicates such changes back to the schematics editor. The schematics editor then either makes the necessary changes to the drawings or assists the user to do those changes.

assumptions on the schematics data model

The schematics (in line with the netlist block) is assumed to built from at least networks and components, components having pins. Each of them have an identifier. Network and component identifiers are unique within the project, pin identifiers are unique within their component.

Furthermore networks, components, pins have attributes, which are key=value pairs. The interpretation of both keys and values are up to the schematics editor.

Fixed attributes are special attributes whose keys are one of those listed in the tables below. Schematics editors are required to support all fixed attributes.

An operation on a fixed attribute may translate into an operation of attributes. The only difference is that the meaning of attribute keys is arbitrary while the meaning of fixed attribute keys is one of a few, tEDAx-specified items. Fixed attributes provide a minimal amount of common API over attributes.

block

Block type is "backann", version is "v1". The unique identifier could be the purpose of the back annotation.

Interpretation of input data

As lines are read, the reader should build an internal model of the original state of netlist, components, pins and an ordered list of change operations to be carried out. If the original state loaded from the back annotation file doesn't match the current state of the schematics, the schematics editor may refuse the back annotation block.

original state lines

command parameter names explanation
net_info network component pin The specific pin of component was originally connected to the network named in the first parameter.

command	parameter names	explanation
net_info	network component pin	The specific pin of component was originally connected to the network named in the first parameter.

network changes

command parameter names explanation
del_conn network component pin The component:pin specified should be removed (disconnected) from the network named in the first parameter
add_conn network component pin The component:pin specified should be added (connected) to the network named in the first parameter
attr_conn network key value Change a network attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

command	parameter names	explanation
del_conn	network component pin	The component:pin specified should be removed (disconnected) from the network named in the first parameter
add_conn	network component pin	The component:pin specified should be added (connected) to the network named in the first parameter
attr_conn	network key value	Change a network attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

component changes

command parameter names explanation
attr_comp component key value Change a component attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.
fattr_comp component key value Change a component fixed attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

command	parameter names	explanation
attr_comp	component key value	Change a component attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.
fattr_comp	component key value	Change a component fixed attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

Fixed attributes for components are:

key value
footprint the footprint name (string) of a component
value the value (string) of a component, with or without unit suffix

key	value
footprint	the footprint name (string) of a component
value	the value (string) of a component, with or without unit suffix

pin changes

command parameter names explanation
attr_pin component pin key value Change a component:pin attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

command	parameter names	explanation
attr_pin	component pin key value	Change a component:pin attribute named in the key parameter to value. If value is missing, remove the attribute. If the attribute did not exist, create it.

Examples

reconnect R3 pin 1 from network vcc to network gnd

tEDAx v1
begin backann v1 bus\ termination:\ pull\ down\ instead\ of\ pull\ up
	net_info vcc R3 1
	net_info vcc U1 3
	net_info gnd U1 2
	del_conn vcc R3 1
	add_conn gnd R3 1
end backann

Note: any of the net_info line is optional. When present, it may help the schematics editor to detect outdated or mismatching back annotation blocks and may help 3rd party software to visualize the pack.

swap gpio pins U1 12 with 16

tEDAx v1
begin backann v1 swap\ GPIOs\ for\ easier\ layout
	net_info btn3 U1 12
	net_info led5 U1 16
	del_conn btn3 U1 12
	add_conn led5 U1 12
	del_conn led5 U1 16
	add_conn btn3 U1 16
end backann

Tune resitor value and size

tEDAx v1
begin backann v1 shunt\ resistor\ tuning
	fattr_comp R14 footprint 1206
	fattr_comp R14 value 100\ mOhm
	attr_comp R14 power\ 0.21W
	attr_comp R14 comment\ layout:\ use\ large\ copper\ pads\ for\ heat\ dissipation
end backann