If you want the cheapest GSM module to send/receive SMS and for basic GPRS usage, this is perfect. Only problem is that, not only is fully undocumented, but there are several other boards based on M590 and the online discussions regarding them may disorient you. You can find the very good hardware design manual and the M590 AT command set in the Neoway site, but there is almost no info on the board itself. I finally found the pinout here: http://arduino.ru/forum/apparatnye-voprosy/ne-rabotaet-neoway-m590 For power, M590 specs define an operating range of 3.3V to 4.5V. The board connects VCC connector pin directly to the M590 VBAT pin without any staging or protection. You need a power supply that can provide 2A, because even if you can establish communication with the module with AT commands, when the RF module kicks-in sending or receiving an SMS, the board restarts if you cannot provide enough current. Do not even think of using power from arduino boards. Note also that USB chargers claiming 2A output, may drop voltage from 5V to 3V when loaded at 1A. M590 I/O pins operate at a reference voltage of 2.85V. The board has 1K resistors ins series with Tx, Rx pins and a 10K resistor tied to VCCIO, so connecting the board directly to arduino pins worked for me. Only problem is that due to the internal clamping diodes of M590, the 5V voltage from arduino Tx pin appears in VCCIO and VBAT pins. I am waiting my order for an adjustable voltage power supply to straighten things out.

If you want the cheapest GSM module to send/receive SMS and for basic GPRS usage, this is perfect. Only problem is that, not only is fully undocumented, but there are several other boards based on M590 and the online discussions regarding them may disorient you. You can find the very good hardware design manual and the M590 AT command set in the Neoway site, but there is almost no info on the board itself. I finally found the pinout here: http://arduino.ru/forum/apparatnye-voprosy/ne-rabotaet-neoway-m590 For power, M590 specs define an operating range of 3.3V to 4.5V. The board connects VCC connector pin directly to the M590 VBAT pin without any staging or protection. You need a power supply that can provide 2A, because even if you can establish communication with the module with AT commands, when the RF module kicks-in sending or receiving an SMS, the board restarts if you cannot provide enough current. Do not even think of using power from arduino boards. Note also that USB chargers claiming 2A output, may drop voltage from 5V to 3V when loaded at 1A. M590 I/O pins operate at a reference voltage of 2.85V. The board has 1K resistors ins series with Tx, Rx pins and a 10K resistor tied to VCCIO, so connecting the board directly to arduino pins worked for me. Only problem is that due to the internal clamping diodes of M590, the 5V voltage from arduino Tx pin appears in VCCIO and VBAT pins. I am waiting my order for an adjustable voltage power supply to straighten things out.

If you want the cheapest GSM module to send/receive SMS and for basic GPRS usage, this is perfect. Only problem is that, not only is fully undocumented, but there are several other boards based on M590 and the online discussions regarding them may disorient you. You can find the very good hardware design manual and the M590 AT command set in the Neoway site, but there is almost no info on the board itself. I finally found the pinout here: http://arduino.ru/forum/apparatnye-voprosy/ne-rabotaet-neoway-m590 For power, M590 specs define an operating range of 3.3V to 4.5V. The board connects VCC connector pin directly to the M590 VBAT pin without any staging or protection. You need a power supply that can provide 2A, because even if you can establish communication with the module with AT commands, when the RF module kicks-in sending or receiving an SMS, the board restarts if you cannot provide enough current. Do not even think of using power from arduino boards. Note also that USB chargers claiming 2A output, may drop voltage from 5V to 3V when loaded at 1A. M590 I/O pins operate at a reference voltage of 2.85V. The board has 1K resistors ins series with Tx, Rx pins and a 10K resistor tied to VCCIO, so connecting the board directly to arduino pins worked for me. Only problem is that due to the internal clamping diodes of M590, the 5V voltage from arduino Tx pin appears in VCCIO and VBAT pins. I am waiting my order for an adjustable voltage power supply to straighten things out.

GPRS Module NEOWAY M590 para Arduino M590 is a kind of single-chip GPRS industrial wireless module with data only. It has SMS, data service and other functions. product features： Dual-band：900/ 1800 MHz Good network compatibility：Certified by the global GPRS R4 agreement Operation temperature ：-40~+80℃, more safety outdoors High reliability：Special EMI/EMC design, still as steady as a mountain with bad electromagnetic environment

GPRS Module NEOWAY M590 para Arduino M590 is a kind of single-chip GPRS industrial wireless module with data only. It has SMS, data service and other functions. product features： Dual-band：900/ 1800 MHz Good network compatibility：Certified by the global GPRS R4 agreement Operation temperature ：-40~+80℃, more safety outdoors High reliability：Special EMI/EMC design, still as steady as a mountain with bad electromagnetic environment

GPRS Module NEOWAY M590 para Arduino M590 is a kind of single-chip GPRS industrial wireless module with data only. It has SMS, data service and other functions. product features： Dual-band：900/ 1800 MHz Good network compatibility：Certified by the global GPRS R4 agreement Operation temperature ：-40~+80℃, more safety outdoors High reliability：Special EMI/EMC design, still as steady as a mountain with bad electromagnetic environment