• Horizontal lines: A, A, B, A, A, B, A, A, B …
• Vertical lines: B, B, A, A, B, B, A, A, B, B, A, A … 

Where 

• A: up – down – up – down 
• B: down – up – down – up

Steps:

• First, we stitch the horizontal lines with basic running stitches.

• Then we stitch the vertical lines.

Finished pattern