KiL89
Newbie level 1
Hi,
I am currently working on a project involving interfacing SIM900 with MSP430. I connect SIM900's TX and RX pins to MSP430 USCI1 module's RX and TX pins (respectively). Also, MSP430 communicates with my PC through USCI0 module (also using UART) for debug purposes. Both USCI0 and USCI1 module of MSP430 are working fine. In my program, every data received from SIM900 will be reflected and sent to PC.
When power up SIM900:
- the STATUS led is on.
- the NETLIGHT led is on for 1 sec, then 64ms On/ 800ms Off for about 5 sec (not find network yet), then 64ms On/ 3000ms Off (has found network).
- when power up, in terminal, I receive "FF FF FF" or sometimes "FF FF FF FF" which I assume that it is the "00 49 49 49 49 FF FF FF FF" string as in SIM900's document mention when power up the module (although I have never received the whole string).
The problem is when I try to send AT commands for example "AT\r" to check communication, I receive no response from the module.
MSP430 is powered at 3.3V while SIM900 module is powered at 4.1V but the logic high level of its serial port range from 2.4 to 3.0V. Do I need a level shifter between them?
Any suggest would be very helpful to me.
I am currently working on a project involving interfacing SIM900 with MSP430. I connect SIM900's TX and RX pins to MSP430 USCI1 module's RX and TX pins (respectively). Also, MSP430 communicates with my PC through USCI0 module (also using UART) for debug purposes. Both USCI0 and USCI1 module of MSP430 are working fine. In my program, every data received from SIM900 will be reflected and sent to PC.
When power up SIM900:
- the STATUS led is on.
- the NETLIGHT led is on for 1 sec, then 64ms On/ 800ms Off for about 5 sec (not find network yet), then 64ms On/ 3000ms Off (has found network).
- when power up, in terminal, I receive "FF FF FF" or sometimes "FF FF FF FF" which I assume that it is the "00 49 49 49 49 FF FF FF FF" string as in SIM900's document mention when power up the module (although I have never received the whole string).
The problem is when I try to send AT commands for example "AT\r" to check communication, I receive no response from the module.
MSP430 is powered at 3.3V while SIM900 module is powered at 4.1V but the logic high level of its serial port range from 2.4 to 3.0V. Do I need a level shifter between them?
Any suggest would be very helpful to me.
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