User's Manual
1.3The Hardware Reference Design
1.3.1 The UART Interface Design
For the equipment of 3.3V power supply,can equipment of serial and module serial
ports directly be linked to each other by the diagram circuit and accomplish
communication;
If the 5V power supply unit can or design the associated level change-over circuit
voluntarity with reference to following circuit,resistance value can be adjusted
according to side circuit.
1.3.2 Power Reguirements
Give module for power supply if produce 3.3V voltage through LDO, then the
capacitance of C1 can be considered with 10u ~ 22u;Give module for power supply if
produce 3.3V through the DCDC power supply, the electric capacity of C1 can be
considered with 47u or bigger alminium electrolytic condenser。
Please guarantee that power supply can provide enough big electric current, power
down occur to avoid module when sending data, the maximum input current of
suggestion module is greater than 330mA
Module leaves two 3.3Vpin, both can select a pin to module voltage to be provided
arbitrarily, also can supply power simultaneously by two pin