GSM V2 power supply

[juliantong]

Hi Benj,
we are testing GSM_V2( EB066 V2) with multi-programmer ( EB006_v9). With regard to the power supply of EB066 V2, we would like to hope that you can help to clarify the following issues:

1) Connect a wire from the 14V screw terminal of the Multi-programmer to +VPWR terminal of GSM board.

a) What is the expected voltage of “14V screw terminal’? even with 14V power supply, the outlet at “14V screw terminal” would still be somewhat 1.4V below 14V.

b) Is it ok to supply a 14V DC power to EB006? Datasheet of EB006_v9 indicates that the board is normally operated from a regulated DC supply of 7.5 - 9V or from a USB supply, and a power supply of 12V may cause the board to run hot.

2) Connect a wire from the +V screw terminal of the Multi-programmer to +V terminal of GSM board.

c) What the expected voltage of +V screw terminal ( 3.3 or 5V) in order for GSM V2 to work properly?

[Benj]

Hello,

1) Connect a wire from the 14V screw terminal of the Multi-programmer to +VPWR terminal of GSM board.
a) What is the expected voltage of “14V screw terminal’? even with 14V power supply, the outlet at “14V screw terminal” would still be somewhat 1.4V below 14V.

The EB006 board has a bridge rectifier diode to allow the DC plug to be either polarity. This does cause about a 1.4V drop on the source voltage and is normal.

b) Is it ok to supply a 14V DC power to EB006? Datasheet of EB006_v9 indicates that the board is normally operated from a regulated DC supply of 7.5 - 9V or from a USB supply, and a power supply of 12V may cause the board to run hot.

It is not recommended to use 14V on the EB006v9, I would go with what the datasheet says. This lower voltage will work fine with the EB066 board and is recommended as you get more current at lower voltages.

2) Connect a wire from the +V screw terminal of the Multi-programmer to +V terminal of GSM board.
c) What the expected voltage of +V screw terminal ( 3.3 or 5V) in order for GSM V2 to work properly?

The +V terminal on the EB006 supplies the target microcontroller voltage to other downstream boards, the GSM needs this voltage to be able to pass signals back to the microcontroller at the correct voltage. The EB006v9 board has a jumper to select the target voltage for most applications I would recommend 5V as you have more current to play with.

[Benj]

I have just had a play with the latest batch of EB066 boards.

They are working but sometimes going into reset so it appears the internal reset pullup has been removed from the IC.

I fixed this by instead of leaving the reset pin floating after pulling it low you should pull it high. This allows the board to power up and work reliably. I'll get the examples updated to match this fix.

[juliantong]

Thank you very much Benj, I am not sure how to "instead of leaving the reset pin floating after pulling it low you should pull it high", and is it modified in program or to change any jumper in board?

Also, I still wonder if my DC power supply (7.5~9V & 1000mA) is appropriate to whole circuit, the result shows GSM v2 is all right with inilization and led light up and signal strength detection(AT+CSQ), but have problems with all other functions (like sms sending and dialing a number, and also incoming sms & call detection). Dose 1000mA is too low for these functions implementation?

Take the shot-message sending (call the function in an endless loop) as an example, many times it returns the value 255; sometimes returns 0, and it seems had send the message sucessfully, but acturally I received nothing.

[juliantong]

Hi Benj
I think I have the same problem with reset, I would be very glad if you can tell me how to fix it in detail. and where I can get your updated example?
THANKS

[Benj]

Hello,

I have posted the latest example here. http://www.matrixtsl.com/wiki/index.php ... 92f491f9af

And on the EB066 product page.

The fix to the file simply outputs a 1 to the reset pin rather than allowing the reset pin to float. Seems the latest modules have a much weaker pull-up on the reset pin or maybe it has been removed altogether.

I still wonder if my DC power supply (7.5~9V & 1000mA) is appropriate to whole circuit

Ideally the GSM module needs 2A of current to supply it's spikes. We use a switch mode regulator on the E-block which exchanges voltage for current and has on hand a large capacitor to supply these current spikes with what they require. Your DC power supply sounds like it should be ok. You could maybe use a scope on the +V voltage rails to see if the voltage is dipping at all. This could indicate that excess current is being drawn and allowing the GSM module to reset.

[Dave Squibb]

Hi, Benj asked me to move to this thread.

I have downloaded the latest test program and have a 14V 2A psu.

The program runs until the LCD displays "Init Fail 255"

I have EB066-00-4. Has the 900MHz / 1800MHz problem been resolved? I have a GiffGaff PAYG SIM (O2?)

Thanks,

Dave.

[Benj]

Hi Dave,

Can you tell me what jumper settings you have on your board. I had mine on B and 1.

The v4 board has certainly sorted out the 900 / 1800MHz issues so this shouldn't be an issue.

In the program is there an output icon near the start that sets portc bit 1 to 0, waits a few milliseconds and then sets it to 1?

[juliantong]

Hi Benj, feel sorry for having questions every day. I still wonder there is something wrong with my EB066-00-2, which really bothering me recently (I have tried the methods you mentioned before).

Acturally, this EB066-00-2 was worked in today and yesterday afternoon (Beijing Time Zone), but just working in few minutes, and then did not work in most of the time (as my previous question).

The hardwares: EB006-00-8(16F1937), EB066-00-2 (Jumper B and 1), Keypad, LCD, 7.5V/1000mA power supply. ( +V: 5; VPWR: 6.1V )

Today I find a phenomenon when it did not work, by comparing with when it was normally work in just few minutes :

1. when it was regular working, initialization has return 0, and led flash every 3 second in idle state, and keep light up if dial a number.
Using multimeter to test SIM card VCC, is always around 2.8V, and supply voltage for GL865-QUAD is always 3.75V. All of them were same as theoretical values.


2. when it did not work in most of the time, after it returns 0 in initialization, the SIMVCC suddenly decline to almost 0 from 2.8V, but supply voltage for GL865-QUAD is always 3.75V as normal, then LED flash every second, and GSM board can not do any function in this condition.


\

I wonder if there is something wrong with the GL865-QUAD?

[juliantong]

one thing to supplement:
no matter it work or not, the GSM board need initialize more than three times in initialization loop, and SIMVCC is up and down more than three times between ~2.8V and ~0V.
if succeed, SIMVCC keeping at 2.8V after initialization, then every thing can work fine.
if not, SIMVCC hold at 2.8V after initialization, and suddenly go to ~0V.
it seems my problem was relevant to the power supply of SIM card

[Dave Squibb]

Hi Dave,

Can you tell me what jumper settings you have on your board. I had mine on B and 1.

The v4 board has certainly sorted out the 900 / 1800MHz issues so this shouldn't be an issue.

In the program is there an output icon near the start that sets portc bit 1 to 0, waits a few milliseconds and then sets it to 1?

Hi Benj,

Yes, jumpers B and 1.

Output 0 >C1
Delay 10mS
Input C1 > Dummy

Downloaded that file this morning!

[Dave Squibb]

Hi Dave,

Can you tell me what jumper settings you have on your board. I had mine on B and 1.

The v4 board has certainly sorted out the 900 / 1800MHz issues so this shouldn't be an issue.

In the program is there an output icon near the start that sets portc bit 1 to 0, waits a few milliseconds and then sets it to 1?

Hi Benj,

Yes, jumpers B and 1.

Output 0 >C1
Delay 10mS
Input C1 > Dummy

Downloaded that file this morning!

Just checked, that's correct. http://www.matrixtsl.com/wiki/index.php ... 92f491f9af

[juliantong]

Really thank you guys, My GSM V2 finally worked.
As Dave mentioned, My problems is solved by instead of my psu(1000mA) by using a DC power generator with a larger current than 1000mA, like following .

THANK you~ Dave and Benj
Julian

[Dave Squibb]

Well done Julian.

@Benj: I have replaced Input C1 > Dummy with Output 1 > C1 in your code and it now appears to work.

Dave.

[Benj]

Downloaded that file this morning!

Sorry, just checked and my upload apparently didn't work. Re-done it now and checked it is correct this time.

Glad your both up and running.