Hi Friends I am using max 3232 for interfacing sim900A module and pic32mx360f512l and for interfacing pic and sim900a module i am using single max3232 ic that is i am used dual channel in max3232 one channel for pic and another channel for sim900a module the problem is when i am sending AT commands to the sim900a module the pic not receiving any response from sim900a module and sometimes its working fine and sometimes its not working. i guess this problem is due to using of both channel used at a same time in max3232 please give me your guidance to resolve this issue
Wrong Connections.... What is your exact application? The method which you are trying to implemented here will not work out.. Explain clearly we will help you to connect properly
Wrong Connections.... What is your exact application? The method which you are trying to implemented here will not work out.. Explain clearly we will help you to connect properly
check if SIM900a can handle 3.3V levels. This is very likely.
if not, then a Si diode and a resistor is OK.
A true level converter, like 74AHC1Gxxx is better solution.
check if SIM900a can handle 3.3V levels. This is very likely.
if not, then a Si diode and a resistor is OK.
A true level converter, like 74AHC1Gxxx is better solution.
Thanks for the reply can you please post the circuit connection with diode and resistor and in my circuit connection the capacitor value is 10uf/20v it is correct or 0.1uf is correct
I read the SIM900 hardware design manual in the way that the digital inputs may be overdriven with current limiting, e.g. 1k series resistors, like many digital circuits.
If you're not sure about, you may want to make a simple voltage divider towards SIM900. Or use schottky clamping. Silicon diodes won't prevent forward bias of the SIM900 internal substrate/clamping diodes.