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SIM900 Customer Flash Loader

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Not sure about your issue PetrolGDA, this sounds a bit like a signal integrity issue, but for benham9856, you must hold down the power key until the firmware has finished. The errors you show are typical of not doing this.
 

sim900.jpg

OK. I did it. But after 13 minutes I got error like on picture.
 

chipseller said:
but for benham9856, you must hold down the power key until the firmware has finished. The errors you show are typical of not doing this.
Click to expand...

Thanks for reply, I hold down the power key during updating... but this error occures:

71818d1333262465-simmm900a.png
 

I'm not sure. more, already tried with the default speed for this operation? 460800 baud. can not remember. but once he had tried to do with different speeds and gave me this error. try the default 460800
 

I seem to remember that the default baud setting is 115200 when the tool is launched. Do not change this as it seems to have relevance other than just the port setting
 

So , you're right, 115200 is the speed of onset, and it is undoubtedly for the operation of AT commands and is for the first 6 .. 7 characters sent, now to the operation of the system bootloader are you sure you also use it? do not forget that it no longer belongs to the same set of operations on this machine.
 

The RAM is loaded in 115200, but the ROM is sent in the selected speed. Before to send the app to module, I set the baudrate to 115200 (AT+IPR=115200). It's not necessary but I prefer to do it.

About the power key, you just need hold it during the RAM Loader process, after it can be released. I'm updating **broken link removed** in 921600 bps, without hold power key during update process.
 

Hello everyone
I have a SIM900B-E module that had a problem with the AT+CMGR command, when reading SMS, that previous SIM340D was doing good, so i decided to flash it with some firmwares i found here, but now it doesn't start, newtork LED is always off.
The flash process application says it was flashed without problems.
Also, the version of this module was 1137B04SIM900B64_SAMSUNG i don't know if i need to look for "SAMSUNG" versions exactly...
Thanks in advance!
 

RafaelLopez said:
Hello everyone
I have a SIM900B-E module that had a problem with the AT+CMGR command, when reading SMS, that previous SIM340D was doing good, so i decided to flash it with some firmwares i found here, but now it doesn't start, newtork LED is always off.
The flash process application says it was flashed without problems.
Also, the version of this module was 1137B04SIM900B64_SAMSUNG i don't know if i need to look for "SAMSUNG" versions exactly...
Thanks in advance!
Click to expand...

Samsung is the flash memory used in this module, another one uses ST flash memory. There are differences in the firmware.
 

Thanks!
That's a nice step into understanding this SIM900B module.
I saw a picture few post ago that shows that 1137B04SIM900B64_SAMSUNG wasn't in the repository.
Could someone lend me a newer "_SAMUNG" firmware?
 
Last edited:

Hi,

i bought another SIM900A... when i hold down the power key for one second, gsm turns on...

before updating, i could send at command like 'AT' and got response... i send at command for pin code of sim

after it i could not set baud rate! i used AT+IPR=115200 and all bit rates, but i got unusual response!

for example when i send AT i got '?' or '{W' and...

so how can i set true baud rate? if i can't set it correctly, i can not update firmware...

by the way, after sending pin code command, when i turn on module, some times status led and netlight led, turns on and not! why?

best regards

---------------------------

now i turned it on, i received these:


IIII????
RDY

+CPIN: NOT INSERTED

+CFUN: 1

NORMAL POWER DOWN

what NORMAL POWER DOWN means? it means that module is off? why?
 
Last edited:

i sent upper case (AT)... remember that i have not update sim900A.

now i wanna know what 'NORMAL POWER DOWN' means? why sim900a goes off?

---------------

IT MAKES ME CRAZY!

now its on and 'NORMAL POWER DOWN' is not show... sometimes i got it!

but i dont know why when I send AT (upper case) i receive nothing or unnormal data!
 
Last edited:

behnam9856 said:
i sent upper case (AT)... remember that i have not update sim900A.

now i wanna know what 'NORMAL POWER DOWN' means? why sim900a goes off?

---------------

IT MAKES ME CRAZY!

now its on and 'NORMAL POWER DOWN' is not show... sometimes i got it!

but i dont know why when I send AT (upper case) i receive nothing or unnormal data!
Click to expand...

'NORMAL POWER DOWN' will be sent by the modem when the module is shutting itself down due to execution of command AT+CPOWD=1 or low going pulse on PWRKEY input pin. I believe, you need to make sure that their is no noise going into the module via the PWRKEY. I suggest you to connect a 0.1uF capacitor (ceramic disc type or electrolytic type) across PWRKEY pin & GND. This will eliminate any ringing (voltage oscillation) on the PWRKEY line.
 

I turned it on, i sent some at commands:


+CPIN: NOT INSERTED

+CFUN: 1

AT

OK

AT+GMR

Revision:1137B08SIM900A32_ST

OK


but after it sim900 turned off and I can not turn it on! I heard that this happened for some guys! and they could not turn it on!

anyone know why? how can I use it again?

PS: the power supply is 12V 2A, using LM7805 and 1N4007 to make 4.2V...
 

so, sim900 is damaged because of my power supply?!
 

i can't found this regulator..
can i use 7809 and lm317 for input voltage?
 

CADiLO said:
>>>> PS: the power supply is 12V 2A, using LM7805 and 1N4007 to make 4.2V...

A very bad decision !!!
Click to expand...

some guys used this schematic that i told u and works correctly!
 

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