Digital Design with VHDL

1. Digital Design with VHDL Presented by: Amir Masoud Gharehbaghi Email: amgh@mehr.sharif.edu

2. Concurrent Statements • Concurrent Signal Assignment • Component Instantiation Statement • Generate Statement • Process Statement • Block Statement • Concurrent Procedure Call Statement • Concurrent Assert Statement

3. Sequential Statements • Signal Assignment Statement • Variable Assignment Statement • IF Statement • Case Statement • Loop Statement • Wait Statement • Procedure Call Statement

4. Sequential Statements (cont.) • Next Statement • Exit Statement • Return Statement • Assertion Statement • Report Statement • Null Statement

5. Block Statement block_label: BLOCK [ (guard_expression) ] [ IS ] block_header block_declarative_part BEGIN block_statement_part END BLOCK [ block_label ] ;

6. D-FF Example ARCHITECTURE guarding OF d_ff IS BEGIN dff_blk: BLOCK (c = ‘1’ AND NOT c’STABLE) BEGIN q <= GUARDED d; END BLOCK; END guarding;

7. D-FF with block header ARCHITECTURE guarding_h OF d_ff IS BEGIN dff_blk: BLOCK (c = ‘1’ AND NOT c’STABLE) PORT(din: IN BIT; qout: OUT BIT); PORT MAP (din => d; qo => q); BEGIN qout <= GUARDED din; END BLOCK; END guarding_h;

8. D-FF with enable ARCHITECTURE nested_guard OF d_ff_e IS BEGIN edge: BLOCK (c = ‘1’ AND NOT c’STABLE) BEGIN enable: BLOCK (e = ‘1’ AND GUARD) BEGIN q <= GUARDED d; END BLOCK; END BLOCK; END nested_guard;

9. Resolution Function FUNCTION anding (drivers: IN BIT_VECTOR) RETURN BIT IS VARIABLE acc: BIT := ‘1’; BEGIN FOR I IN drivers’RANGE LOOP acc := acc AND drivers(i); END LOOP; RETURN acc; END anding; … SIGNAL a: anding BIT; … a <= b; a <= c; a <= d;

10. Configuration CONFIGURATION identifier OF entity_name IS { use_clause } FOR architecture_name { block_configuration } END FOR ; END CONFIGURATION; block_configuration ::= FOR block_specification { use_clause } { configuration_item } END FOR ;

11. Configuration (cont.) configuration_item ::= block_configuration | component_configuration component_configuration ::= FOR component_specification [ binding_indication ; ] [ block_configuration ] END FOR ;

12. Configuration Example CONFIGURATION default_c OF test_comp4 IS FOR customizable FOR a1: comp4 USE ENTITY WORK.nc4(flexible); FOR c0, c3: comp1 USE ENTITY WORK.bc1(fixed);END FOR; FOR c2to3: comp1 USE ENTITY WORK.bc1(fixed); END FOR; FOR flexible END FOR; END FOR; END FOR;