WEMOS D1 And SIM900 GSM/GPRS Shield

Projects Networking, Protocols, and Devices
1

Hello

I need your help because I try to connect my 2 boards WEMOS D1 and SIM900 GSM/GPRS Shield but I dont understand which pin I must connect

D1
SIM900

Is someone know how to connect it ?
And how test it ?

Many thanks by advance

2

which Wemos D1 is it?
have a look at software-serial-esp8266 which you should be able to use to connect the D1 to ethe SIM900

3

It's the WeMos D1 WiFi UNO like WeMos

4

just connected up a Wemos D1 mini pro to a SIM900
using the following code

// ESP8266 SoftwareSerial
// https://circuits4you.com/2016/12/14/software-serial-esp8266/

#include <SoftwareSerial.h>

// pins Rx GPIO14 (D5) and Tx GPIO 12 (D6) 
 SoftwareSerial swSer(D5, D6);//14, 12);  

void setup() {
  Serial.begin(115200);   //Initialize hardware serial with baudrate of 115200
  swSer.begin(9600);    //Initialize software serial with baudrate of 115200
  Serial.println("\nESP8266 Software serial test started");
}

void loop() {
  while (swSer.available() > 0) {  //wait for data at software serial
    Serial.write(swSer.read()); //Send data recived from software serial to hardware serial    
  }
  while (Serial.available() > 0) { //wait for data at hardware serial
    swSer.write(Serial.read());     //send data recived from hardware serial to software serial
  }
}

D1 serial monitor displays

RDY
+CPIN: NOT INSERTED
+CFUN: 1
at
OK
AT+cgmi
SIMCOM_Ltd
OK
AT+CGMM
SIMCOM_SIM900
OK

Edit: connected up a Wemos D1 same as yours SIM900 RXD to D6 and TXD to D5
works OK

5

Ok so for you D6 is pin named D12/MISO/D6 and D5 is pin named D13/SKD/D6 on Wemos ?
And where is the RXD and TXD on SIM 900 ? We use Hardware Serial (D0 D1) or Software Serial (D7 D8) ?
Many thanks for your feed back

6

yes

image
image763×436 99.3 KB

photo

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image1037×778 115 KB

7

Many thanks ..
I busy now but I will test it quickly

8

Hello horace

Many thanks for your help but it seem to not ok for me
I take photos about cards and program but
swSer.available() is always equal to 0

https://ibb.co/vx0Dz19
https://ibb.co/MSR3FV4

I not put SIM card in SIM900

I you have idea about my errors, i take

Many tanks

9

Hello
I tested le SIM900 by FTDI connection with AT command and all is ok
I tried to send au SMS and read it
So I connect Wemos to SIM900 like schema and use the sketch but nothing work ok

I select LOLIN (WEMOS) D1 R2 & mini in Arduino IDE and user serial library
name=SoftwareSerial
version=1.0
author=Peter Lerup
maintainer=Peter Lerup peter@lerup.com
sentence=Implementation of the Arduino software serial for ESP8266.
paragraph=
category=Signal Input/Output
url=
architectures=esp8266

Have you an idea about misteke

Many thanks

10

when you press the SIM900 button to switch it on does anything appear on the serial monitor even garbage?
how are you powering the SIM900?
it may be in autobaud mode try typing at at at a number of times

11

When I turn on the SIM900 nothing display on serial
When i press the D1 button,

SDK:2.2.2-dev(38a443e)/Core:3.1.1=30101000/lwIP:STABLE-2_1_3_RELEASE/glue:1.2-65-g06164fb/BearSSL:b024386

ESP8266 Software serial test started

I powering the SIM with 5V 2A alimentation and I try typing at but nothing.

I looking for again

12

when you power the SIM900 the PWR LED should light
if you press the PWRKEY on the SIM900

  1. the STATUS LED should light
  2. the Netlight LED should blink

and the following appear on the serial monitor

RDY
+CPIN: NOT INSERTED
+CFUN: 1

should then be able to enter AT commands - note line ending should be Carriage Return or NL & CR

13

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