I have interfaced a 12 V pump and a 12 V fan to LPC2138, there are 3 5 V sensors interfaced, according to which the fan and pump function. The whole setup is in PCB. There is a ESP8266 module interfaced to controller. The decision to switch on or off these output devices (fan and pump) is given through the server end( WiFi connectivity). The problem that I am encountering is that whenever both the devices that is the fan and pump switch on together, the whole circuit either disconnects, or resets or the stops functioning normally (LCD displays vague values), what should I do??? Please help. The whole system is powered by a on board PCB voltage supply, where a 0-12V 1A transformer is used and voltage regulator ICs (plus design which includes rectifier, capacitors etc) are used to divert 12V, 3.3V and 5V dc supply voltages.
It sounds very likely that your power supply is not able to provide enough current for the fan and the pump while maintaining proper supply voltages for the computing parts of the design. It's as simple as that.
You haven't provided a schematic or links to the datasheets for your components so more detailed help is not possible.