Author Topic: E-Gizmo SIM900D GSM/GPRS Shield (Read 2165 times)

RiDdLeR??? · « **on:** June 11, 2012, 02:59:34 PM »

Just got the gsm/gprs shield. To those with the old SIM900D gsm/gprs modem or with the SIM900D gs/gprs shield, have you ever experienced that upon power up, the modem will immediately turn off ... the status led will be off and you cant issue any at commands anymore.

This is experienced mostly on a globe sim and sometimes on a smart sim. I don't experience this with a red mobile sim whose signal quality is far less compared to globe and smart. any ideas? Can this be a PSU problem?

Philippine Electronics Forum · « **on:** June 11, 2012, 02:59:34 PM »

PlCUSER · « **Reply #1 on:** June 11, 2012, 03:18:24 PM »

Experience ko with the automatic shutdown feature sim900 e kapag connecting to a gprs network. Gumamit lng ako recommended voltage regulator, ok na. Wala na ung antukin problem. Ung regulator eh nasa datasheet.

Philippine Electronics Forum · « **Reply #1 on:** June 11, 2012, 03:18:24 PM »

Born2BeWired · « **Reply #2 on:** June 11, 2012, 03:44:11 PM »

Ate alyas, the SIM900D module requires just a few milliamp on average, but requires a rather high current during its short bursts of transmission. Like when it is registering to the network provider. If even for a brief period of time the supply line drops below 3.5V (I think), the module will shut off. Hence, a power source with at least 1.5A current rating is required.

There is a walk around deviced by insomartin and published somewhere in this forum. He added a gold cap across the supply line. Works like a charm even with low current capacity source as long as you do not use the module for continuous transmission (i.e. voice).

Philippine Electronics Forum · « **Reply #2 on:** June 11, 2012, 03:44:11 PM »

RiDdLeR??? · « **Reply #3 on:** June 11, 2012, 03:54:34 PM »

Minomonitor ko yung vbat, di naman nag di-dip, constant 3.9V ang vbat.

What I have found out now is that when the signal strength is strong, more than 12 (from at+csq), nag auto-off ang modem.Kaya pala walang problem kapag red mobile sim gamit ko since the signal is weak or walang gprs network profile yung red mobile som ko.

May point si sis picpic, the modem would only try to register to the gprs network when a certain signal quality is present so baka psu problem nga. Kung yung regulator or yung ac adapter, I have to find out but the regulator used is only rated at 1.5A and may over current protection siya so first suspect is the regulator and I've read from the datasheet na 2A ang peak current draw ng sim900d.

As I'm not yet interested in gprs and ip, pag-aralan ko muna idisable ang gprs network registration through at command.

Philippine Electronics Forum · « **Reply #3 on:** June 11, 2012, 03:54:34 PM »

RiDdLeR??? · « **Reply #4 on:** June 11, 2012, 04:43:38 PM »

no good, the modem turns off before I can even issue an at+cgreg=0, will now concentrate on getting a psu with agood transient response. Capable naman yung ac adapter ko to supply more than 2A.

Also tried to solder 3x 1,000uF sa Vin, ganun pa rin.

Philippine Electronics Forum · « **Reply #4 on:** June 11, 2012, 04:43:38 PM »

toasted siopao · « **Reply #5 on:** June 11, 2012, 07:01:16 PM »

Ito yung mga na try ko na sa sim900D, kahit may super cap sya, kung around 1A lang power supply, nagsashutdown pa rin after 1 or 2 min, lalo na kapag mahina signal.

Kailangan at least 3A power supply para stable without super cap or make sure na talagang kaya ang 2A at peak loads.

maldihtah13 · « **Reply #6 on:** June 11, 2012, 07:29:31 PM »

I had the same experienced. I just replace the capacitor.

PlCUSER · « **Reply #7 on:** June 11, 2012, 11:16:59 PM »

may mga lipo ka pa ba ng old heli mo sir alyas. try mo un, baka pwd.
gusto ko sanang subukan sa 2S 3S ko, kaso tamad pa ko.

RiDdLeR??? · « **Reply #8 on:** June 12, 2012, 01:05:44 AM »

Yup subukan ko dun sa mga lumang 2s ko. Kaya pala yung smd cap na c2, pinalitan ng 470uF na TH. Sabi nung nagdonate sa akin nitong shield eh nakailang palit muna (siguro mga 5 times) bago nakapagtest ng unit na maayos eh gumagamit naman daw yun ng lab grade PSU so obviously psu capacity is not a problem .... di kaya kailangan ng bagong firmware ng sim900d?

RiDdLeR??? · « **Reply #9 on:** June 14, 2012, 02:17:10 PM »

mukhang f/w issue .... I did some observations the past few days, when csq is 12 and below or 19 and above, the module powers up w/o any problems. Its only when csq is between 12 and 19 where the module auto powers off.

PlCUSER · « **Reply #10 on:** June 14, 2012, 02:23:30 PM »

arbor na lng yan sir alyas.

RiDdLeR??? · « **Reply #11 on:** June 16, 2012, 12:06:50 PM »

may bagong f/w for sim900d ...subukan ko muna magupdate ng f/w at paglaruan yung debug tx/rx

RiDdLeR??? · « **Reply #12 on:** June 16, 2012, 05:09:24 PM »

Ayos na! tama si Toasted, dapat at least 3A. Di pala kaya ng 2A switching ac/dc adapter ko ... ginamitan ko ng 3.5A switching PSU and di na namatay.

toasted siopao · « **Reply #13 on:** June 16, 2012, 08:06:51 PM »

I would not advise a switching supply lalo na kapag biglaan ang pag sink ng current sa load, napansin ko ito using a highcurrent dc to dc sa pag drive ng servo. Di kaya ng dc to dc regulators ang high current transients, kahit pa naglagay ako ng malaking capacitor sa output, talagang di kinakaya..

keyholder · « **Reply #14 on:** September 07, 2012, 10:05:05 AM »

Wala bang ibang alternative sa 3.5A supply like using capacitors? Di ba talaga gumagana yun. We are experiencing the same issue. Grabe, kelangan ng supply na kayang magsupport ng 3A para gumana ng maayos yung shield. Unlike yung Maestro, napagana namin in 1.5A, with Gizduino pa yun.

Within seconds, bumagsak yung charge ng battery from 6.3V to 4.7V. Bagong bili pa naman to. O_O!

maldihtah13 · « **Reply #15 on:** September 07, 2012, 10:36:37 AM »

Grabe pala requirement. Sana wala ako makita ganun issue.

keyholder · « **Reply #16 on:** September 07, 2012, 10:49:23 AM »

15 min! Yun lang ang tinagal ng 2 x 5pcs 1800mAh NiMH battery pack na nakaparallel connection. Saklap, malaki ang konsumo. Hehe. Kelangan humanap ng alternative or better code.

insomartin · « **Reply #17 on:** September 07, 2012, 12:35:07 PM »

let me guess.. may LCD yan at enabled ang backlight?

keyholder · « **Reply #18 on:** September 07, 2012, 01:14:16 PM »

Wala sir martin. GSM shield na nakakabit lang sa Gizduino v3.1. Hehe. Tinest lang namin gano tatagal. Gumawa kami ng bagong procedure. Chinarge namin yung battery ng upto 1.5V per battery, eto tumagal na ng 2 hours so far. Bawat minuto nagsesend ng SMS report.

toasted siopao · « **Reply #19 on:** September 07, 2012, 01:23:02 PM »

Check mo parameters ng initialisation ng gsm modem, another is your signal strength, try mo gawa sarili mo antenna.

Philippine Electronics Forum · « **Reply #19 on:** September 07, 2012, 01:23:02 PM »

Author Topic: E-Gizmo SIM900D GSM/GPRS Shield (Read 2165 times)

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