Physical Requirements
This lesson covers how AP 210 represents physical design requirements. We use the ATX motherboard envelope as an example.
The ATX Envelope Example
The ATX form factor defines:
Maximum board dimensions: 305mm x 244mm (full ATX)
Mounting hole positions and sizes
I/O shield opening dimensions
Component height restrictions by zone
Keepout areas around the CPU socket
Requirement Entities
AP 210 captures requirements using:
product_definition_relationship - Links requirements to the design
shape_aspect - Identifies the specific feature being constrained
measure_with_unit - The numerical requirement value
tolerance - Acceptable variation from the nominal value
Dimensional Requirements
A maximum board length requirement:
#100 = SHAPE_ASPECT('board length', 'overall dimension', #board_shape, $);
#101 = DIMENSIONAL_SIZE('length', #100);
#102 = MEASURE_WITH_UNIT(LENGTH_MEASURE(305.0), #mm_unit);
#103 = TOLERANCE((#104, #105), #102, 'maximum');
#104 = PLUS_MINUS_TOLERANCE(0.0, $);
#105 = PLUS_MINUS_TOLERANCE(-5.0, $);This specifies: maximum length = 305mm, tolerance range: 300mm to 305mm.
Keepout Zones
A keepout zone defines where features cannot be placed:
#200 = SHAPE_ASPECT('CPU keepout', '', #board_shape, $);
#201 = GEOMETRIC_ITEM_SPECIFIC_USAGE('keepout zone', '', #200, #board_shape);
#202 = ADVANCED_FACE('keepout boundary', ...);Component Height Restrictions
Height restrictions by zone:
#300 = PROPERTY_DEFINITION('max component height', '', #zone_shape);
#301 = PROPERTY_DEFINITION_REPRESENTATION(#300, #302);
#302 = REPRESENTATION('height limit', (#303), #length_context);
#303 = MEASURE_REPRESENTATION_ITEM('height', #mm_unit, 25.0);