Features: 1.SCOPE OF APPLICATION: SIM7028 expansion board for RasPi 2 2B 3B 3B+ 4B, supports TCP, UDP, LWM2M, COAP, DTLS, DNS, NTP, HTTP(S), MQTT(S), TLS/SSL and other functions. 2.TYPE C INTERFACE: Expansion board on board Type C interface, can be used for software debugging, etc.; on board UART interface, can be used for AT command sending and receiving and firmware update. 3.USB TO UART CHIP: USB to UART chip on board, UART communicate pins can be set through the jumper cover, on board nano SIM card slot, support for NB IoT special card, derivation out the control pins, can be accessed for STM32 and other main control board. 4.SUPPORT AT COMMAND CONTROL: Expansion board supports AT command control (3GPP TS 27.007, 27.005 and SIMCOM Enhanced AT command set); Support SIM Application Toolkit (SAT Class 3, GSM 11.11, USAT). 5.SUPPORT SERIAL BAUD RATE: NB IoT HAT expansion board supports serial baud rate from 2400bps to 460900bps (default 115200bps). specification:Item Type: SIM7028 NB IoT HAT Material: PCB Supply Voltage: 2.2V to 4.3V Logic Voltage: 5V/3.3V (Default is 3.3V) Sleep Mode Current: 0.11mA (DRX=2.56s) Power Saving Mode Current: 0.8uA Operating Temperature: -40C to 85C Storage Temperature: -45C to 90C Supported Frequency Bands B1/B2/B3/B4/B5/B8/B12/B13/B14/B17/B18/B19/B20/B25/B26/B28/B66/B70/B85 (Check with your local operator to see if the NB-IoT card is suitable for this band, not included) Transmission Power: Class 3 (0.25W LTE) Data Transmission: Uplink: 159Kbps Downlink: 127Kbps PackageList: 1 x Expansion Board 1 x Antenna 1 x Screw Package 1 x Pin 1 x USB Cable NoteB1/B2/B3/B4/B5/B8/B12/B13/B14/B17/B18/B19/B20/B25/B26/B28/B66/B70/B85 (Check with your local operator if NB IoT card is applicable for this band, card not included)