Fig. 4
From: Design and implementation of a simple and inexpensive respiratory synchronization control platform
(Three panels). Enhancement of the original program shown in Fig. 2 to provide both a 2-line by 16-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). These pushbuttons are used to enter (K1) and exit (K4) setup mode as well as to cycle through available selections for respiratory rate (K3) and I:E ratio (K4) when in setup mode