If you are using WiFi and your phone goes into sleep mode, then FoodZaps will not able to communicate with other devices unless the Wi-Fi sleep settings are set correctly. Steps below.
On your Android device:
For Android 2.3 and earlier
1) Navigate to Menu > Settings > Wireless & Networks > Wi-Fi settings> and select the menu button again.
2) You’ll be prompted to either scan or select advanced. Select “Advanced”
3) Select “Wifi sleep policy” , and you will have a couple of options to select from. Choose “Never”.
For Android 4.0 (Ice Cream Sandwich) and later:
1) Navigate to Menu > Settings > WiFi and select the menu button again.
2) Select Options, Advanced
3) Set “Keep WiFi on during sleep” to “Always”