i 0 interface 14 of the electronic controller 10 comprises the start stop switch 21 the pattern selecting unit 22 comprising the numeric keys which are operated to enter a number of two figures representing a pattern to select a desired pattern the enlargement switch 23 and the reduction switch 24 the standard pattern size i e the default pattern size stored in the rom 12 of a pattern is enlarged or reduced by one degree every time the pushbutton of the enlargement switch 23 or the pushbutton of the reduction switch 24 is pushed thus a desired pattern size is determined by pushing the pushbutton of the enlargement switch 23 or that of the reduction switch 24 a corresponding number of times in this embodiment the pattern width can be changed stepwise in the range of 3 mm to 9 mm in a 0 5 mm step the driving unit 30 comprises the main motor 31 a sewing motor driving circuit 32 for driving the main motor 31 the feed motor 33 a feed motor driving circuit 34 for driving the feed motor 33 the swing motor 35 for swinging the needle bar 61 in directions perpendicular to the feed direction in which the workpiece is fed and a swing motor driving circuit 36 for driving the swing motor 35 the driving circuits 32 34 and 36 are connected to the i 0 interface 14 of the electronic controller 10 to drive the motors 31 33 and 35 respectively according to control signals given thereto by the electronic controller 10 the timing pulse generator 40 comprises a disk attached to the main shaft of the stitch pattern sewing machine and a photointerrupter the timing pulse generator 40 generates a timing pulse signal synchronously with the.