Geekstory 4G GPS GSM GPRS Module SIM7100A Development Board 5-18V LTE WCDMA GNSS B2 B4 B15 + GPS Antenna for Arduino Raspberry Pi Window Linux

Nice little board from GerkstoryPositives: Excellent little Modem with a nice 7100A and stand-alone GPS mode. The GPS was actually quite excellent when stationary and the NMEA can be fed into most GPS mapping programs. Please note the geoid to ellipsoid Height was off in the NMEA messages from the 7100A, but HaE was correct.The 7100A AT commands are actually very, very well documented using one of the links the seller provides in the Q&A section or you can get directly from the manufacturer.Negatives: No PCB level diagrams available that I can find from the seller. The Vbat and UART are confusing and the voltage input is very touchy. One needs a Solid 5.1V input to get the unit to turn on with the push button, anything less and only one led will ever stay lit. Also, it didn’t like 5.2V from an Anker powerbank (likely noisy voltage)For the UART port to work, it was suggested you need to attach the voltage reference you want for UART to the Vdd. Basically 3.3V or 5V attaches to Vdd pin for that voltage output to be present on the TX pin.Unknown if Vbat pin can support charging a small LiPo battery or if it is only for a LiPo battery voltage input instead of the 5.1V source. I was able to power the unit with 3.8 volts on that port.The unit can be powered on by connecting the pwr (pwr key pin input) to high momentarily 200ms - 500ms. It doesn’t always work to turn off the unit if the 7000A hangs, so be prepared to so hook up a wire to the reset pin and send a reset high logic signal to get it to power off if pwr key fails, also one could also try to use the AT command to shut it down.Also, upon first power up, the pwr key may get a failed start, and you have to apply the pwr key a high signal a second tome to get the unit to turn on (could be a capacitor charging inside or power supply issue not related to the 7100A board).When changing the APN for the SIM, I had to stop the cellular data connection using AT commands before the apn setting could be modified for the Pid #1 default settings. (See 7100A AT command Manual)Also, Some AT commands like sending an SMS on this PCB require a “Ctrl-Z” ascii character at the end of the AT command

This module works great. You will need to utilize the power key if using remotely. Otherwise a little digging in the questions section of the amazon listing and on google will net you plenty of documentation.

The first 2 months was phenomenal performance. As you continue to use the full functionality of SIM7100A, we noticed that the response from AT+GPSINFO=,,,,,,,,, .There is no support and therese is no one you can talk to about the repairs or replacement.We bought about 17 pieces of this from various 'resellers' (just to be clear) and they all have the same symptoms.If the reseller is listening - you might want to change your Support positioning for this type of product.