Fig. 5From: Design and implementation of a simple and inexpensive respiratory synchronization control platformPhotograph of the prototype for the advanced system corresponding to the code in Fig. 4. Note the presence of a 2-line by16-character LCD display (for displaying the respiratory rate and I:E ratio) as well as a 4 × 1 array of pushbuttons (K1, K2, K3 and K4) used to setup (initialize) the operation of the unit. Notice also the illuminated green LEDBack to article page