H/W Reset for SIM300 - need help

[gravi]

H/W Reset for SIM300

Hi

I have been using SIM300 module in one of my application. I have noticed minor issues in its responce.

1. When I Send SMS, some times the message in the SMS contains commands which I have given to modem.

2. Some times modem will not respond to the commands.

So I am planning to interface a circuit which could reset my modem with respect to microcontroller when ever required.

can any one suggest me any circuit.

Thanking You
Ravi Kumar

 

[karthi_keyan]

Re: H/W Reset for SIM300

hai,
Ravi this kind of problem arises due to power supply..the module ll take more current while sending msg, gprs & call connecting..so check the followings,
1.power supply should capable of delivery current more than 2A.
2.if the circuit is ur own design check voltage carrying line thickness.if it is too thin reset may occur often.

Do the followings if u are sure with the power supply design,

1.connect the pwrkey pin ,status & net light pins with your controller.configure pwrkey pin as output and net light,status pin as input.pull down the pwrkey till net light or status pin gets high.(write using OR).it used to turn on alone.write turn off function with same procedure pull down the power key till the status and pwrkey gets low(here use AND).It takes 5 sec to reset.(use transistors if your controller doesn't satisfy voltage levels of modules check data sheet)

2.use AT+cpowd=1,to reset but it takes more than 15 sec.

last thing if ur board is evaluation board u cant take the pin which i have mentioned above and only way is to reset the modem by relay.

REGARDS,
KARTIKN

 

[gravi]

Re: H/W Reset for SIM300

Hi,

I have been using sim300 from 3 years, I hope my power supply and reset circuit is fine.

i would like to switch ON/OFF modem circuit from microcontroller. can any one suggest me a circuit.

Thanking you
Ravi Kumar