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I have the question, I used SIM300 without connection RTS and CTS signal.
Few days ago I bought the SIM900 (without D, the smallest package 24x24mm) and I have had problems because: “ Factory settings is auto-bauding enabled.”(now at first I must synchronize baud rate in connection).
Maybe you have any upgrade hardware with autobauding disaled or have any other solution of this problem.
I need reduce connection lines in my project and I do not want to use RTS and CTS signals.
Which (presented here) hardwares will be the most suitable for my SIM900???
Another question is: What is the main difference between SIM900 and SIM900D??
Of course apart from the size and the number of pins. SIM900D is replacement of SIM300 but what about SIM900??
Hi again all,
If any of you guys still around, hoping you could help me!!!
I got a new sim900 module and tried to flash it according to the instructions given by chipseller. (before flashing I set the baud rate to 115200) Out of the box, my firmware revision was 1137B08SIM900M64_ST and was working fine. I wanted to re-flash to the newest version 1137B09SIM900M64_ST. So I downloaded the firmware files given by chipseller and used the "Simcom - sim900 Customer flash loader V1.01.exe" to download the firmware. Everything went ok and I got the message "Download Done"
However, the problem came when I tried to re-connect with the gsm module using Hyperterminal. I again set the baud rate to 115200 and turned on the gsm module. Instead of the usual responses, I got a some garbage ascii characters from the sim900. This usually happens when the baud rate is set incorrectly, so I tried different baud rate settings. But still all I got was some garbage characters.
Because of this I then uploaded the old firmware version in to the SIM900. (1137B08SIM900M64_ST) But the results were still the same.
The GSM module seems to be working well. It turns on and the "NET" light indicates that i registers withe the network as well. However, I can't communicate with it.
Any idea what's going on? Some help would be much appreciated.
thanks
Do you mean 115200 or 15200? 115200 shows on the flashloader because it is a code (option 1 - 15200). My dev kit runs by default at 9600. I suspect that you need to persevere.
That there are rubbish characters at least indicates that the module is trying to autobaud, but Hyperterminal just can't do autobauding as it needs to send a stream of characters until it recognises the response.
HI Chipseller,
Thanks for the answer. I was using 115200 to communicate with the sim900, before, during and after the re-flashing. (I don't see a 15200 option in the flash loader ??) I also tried re-flashing at 9600 (takes a while) but even that resulted in the same behavior. One thing that I've noticed is that, regardless of the baudrate setting on the sim900 (which was set by AT+IPR) the flash loder works with any baudrate, and doesn't give an error when the buadrate settings on the flash loader and sim900 are different.
Going along with your response, I think my problem could be that the sim900 is trying to auto-baud. If that is the case, and as you say if hyperterminal doesn't support auto-bauding, what should I do to re-establish communication with the sim900?
UPdate: It was the auto-bauding (phew) Figured it out after reading the AT command guide. Once the sim900 powers up, you have to wait a while (for about 5 sec) and then in hyperterminal type "AT". I was typing "at" all this time and that's why the sim900 did not properly sync up with the PC.
AW, thanks a lot chipseller for the insight. you really saved my day
Maybe you can help. I am trying to re-FLASH a SIM900D that is already soldered in place, I have access to the main UART but not the debug port (without soldering wires in place), however I noticed in a previous post you mentioned it can be programmed through the main UART.
I am updating the firmware because I would like to take advantage of the new DTMF detection. I am using firmware version "1137B08SIM900M64_ST_DTMF_JD_MMS" which you posted earlier.
However I am getting an error message as sown attached:
I am using a USB to RS232 adaptor, but I use this allot for other tasks and it works ok.
The sequence's I have tried are:
1) Power-off SIM900D -> PWRKEY to GND -> click start -> Power-up SIM900D
2) Power-up SIM900D -> PWRKEY to GND -> click start
method 2 just sits and does nothing with the message: "Please power up the target"
Hi Chris,
Maybe I can help you with this. The error that you get is because of not resetting the GSM module to sync up with the flash downloader to initiate the download process. Do you have a sim900-rest button on your board? (tied to the RESET pin of the sim900) if so you can use the following procedure, which I use.
1.) connect pc to the uart port of the sim900
2.) power up the module
3.) start the flashdownloader software and select the file
4.) press start in software and immediately press the reset button. (note: you need to press the reset button immediately after pressing the start. I usually keep my finger on the reset button before clicking start.
5.) if this works, you should see the following message in the software ""Flash Erasing. Please wait.." This takes some time to complete and after a while you should see the programming happening.
I think you can get this to work using the power key also. Not sure how.
Also note that if you have the baud rate to 9600, the programming will take forever to complete. I usually use 115200. It still works for me without any problem.
I shall give your method a try right away and let you know how I get on.
Regards
Chris
---------- Post added at 16:18 ---------- Previous post was at 15:35 ----------
Hi Dinuka,
I've got it working, I doesn't seem to be a reset pin on the SIM900D, however I found the source of the problem.
In the end I soldered my USB adaptor direct to the debug pins and it still wouldn't work, so i scoped the RX and TX lines and found that the adaptor was sending out spurious data when no comms activity was present. After a thourugh checking i found that a the ground from the PCb was missing to the adaptor, after connecting the ground the spurious data disapeared and i could program no probs.
Incidently thank you very much for the baud rate tip, it would have taken FOREVER at 9600 baud.
Also for those who are interested the correct sequence to program a SIM900D without a dev board is:
1) PWRKEY no connection & VCC powered OFF
2) PWRKEY to GND
3) With correct file selected, click start
4) When prompted power-up VCC
5) Wait a long time...
Thanks for your help Dinuka.
---------- Post added at 16:24 ---------- Previous post was at 16:18 ----------
Just thought I'de add, after changing firmware on SIM900D to version "1137B08SIM900M64_ST_DTMF_JD_MMS" the version now shows as SIM900 not SIM900D. All seems to work so far, and most important the DTMF detection works great!
Would like to know if anyone has a "D" version of the firmware though?
Chris:
This was a special release of the firmware from Sim. If You are using the D because you need both audio channels you may run into problems as this is a single-channel build, but everything else is the same. Sim have not, so far released a production version of this for other types.
Thanx chipseller for the Firmware and the flashing tool i couldn't find it nowhere, and i had a problem that the simcom modul didn't recognized some sim cards, but after I updated it to the 1137B08SIM900M64_ST it worked fine
I then tried to update it to the 1137B09SIM900M64_ST and i got a checksum error.
If you have some newer FW for the SIM900 please post it here, or if someone can tell me what's that problem is it would be nice .
You have the latest version. I do not understand why there is a checksum error unless the file got corrupted while being downloaded or unpacked. No-one else has reported any issues and quite a few people have used that file. Try downloading the file again, to a new location and unpacking it with a different tool to the one you are currently using. Let me know how you get on
Hello Good People
I have run into a problem while trying to flash my SIM900 on an EVB
Here are the steps i followed
Select FW and clicked start
Switched S102 (download) to the on position
Switched S105 (Power) to the on position
The process begins then encounters the error shown in the attachment below
The current FW is 1137B07SIM900M64_ST
The ones i have tried to flash are chipseller's 1137B09SIM900M64_ST.rar and 1137B08SIM900M64_ST.rar
Can anyone point the way forward?
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