Arduino UNO w/o shield SMS problem

The SparqEE CELLv1.0 device.
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Joined: Thu Dec 01, 2016 12:48 am

Arduino UNO w/o shield SMS problem

Postby Gab » Thu Dec 01, 2016 1:38 am


We've recently started a project that involves an Arduino UNO being wired to a Sparqee Cellv.10 in order to provide
the capability of SMS sending to the UNO. We intend to power the Cell solely from the UNO and we have no shield to
make the circuitry space efficient. The following are our wiring connections based on the Sparqee site and the info
we've gathered from the forum:

Arduino <-> Sparqee Cell
pin 6 <-> Tx
pin 7 <-> Rx
pin 9 <-> PO
5V <-> Vin (shunted to Vo)

The code we are using to make the initial test is as follows:

Code: Select all

#include <SoftwareSerial.h>
#include <String.h>

int rx = 6;
int tx = 7;
int po = 9;

SoftwareSerial mySerial(rx,tx);

void setup() {

  pinMode(po, OUTPUT);       
  digitalWrite(po, LOW);
  digitalWrite(po, HIGH);
  //turning the Cell on

  mySerial.print("at+cmgs=\"<mobile number>\"\r");
  //SMS sending


void loop() {


All we've got thus far from the following set-up is a humming sound from the Sparqee cell. The message did not arrive on the phone
where the mobile number belongs to. We also like to note that we're using the Arduino IDE.

We would very much appreciate your help regarding this matter.

Thank you!

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Re: Arduino UNO w/o shield SMS problem

Postby donjohnii » Thu Dec 01, 2016 8:48 am

You're overdriving the board... the voltage on the Vin line is supposed to be a regulated 3.4-4.2V if it's an input. You should be shorting Vin to Vref if you're not using the shield as the shield shunts those pins together to run the 5V line through the regulator.

This is referenced on the main cell page:

Here is the datasheet with explanation for pins: ... et_v10.pdf

The sound may be an indication that the power supply is being supplied a dirty power source, voltage range issue, low current, or main inductor is bad.

To validate that the module is getting the right power, you can make sure there is about 3.5V on Vo - this should be measured by the positive DMM lead on Vo (pin 9) and the negative on GND (pins 20, 21).

Once power is figured out, it's best to use a UART converter to communicate directly to the CELL vs through the Arduino, just to make sure it has network connectivity and everything is functioning well.

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