SIM800C,32Mbit

The SIM800C,32Mbit from SIMCom is a variant of the popular SIM800C GSM/GPRS module that doubles the integrated serial Flash memory from 16Mbit (2MB) to 32Mbit (4MB). This additional Flash memory provides more space for firmware updates, application code storage, and data logging in the module’s file system. The SIM800C is a complete Quad-Band GSM/GPRS solution in a compact 15.8 x 17.8mm LGA package, integrating the RF transceiver, baseband processor, power management, and 32Mbit serial Flash in a single module. The module supports all GSM/GPRS services including voice calls, SMS, MMS, and GPRS Class 12 data (up to 85.6kbps). The integrated 32Mbit serial Flash is accessible through the module’s AT command file system, allowing the host MCU to store and retrieve data files without external memory. The additional Flash is particularly useful for over-the-air (OTA) firmware updates, where the new firmware image can be downloaded to the Flash before being applied, and for applications that need to log large amounts of data locally before transmitting. The module operates from a 3.4V to 4.4V single supply, drawing up to 2A during GSM transmit bursts (577us every 4.615ms), requiring a supply capable of delivering the peak current with minimal voltage droop. The UART interface supports baud rates up to 115200bps for AT command communication, while the PCM interface supports digital audio for hands-free applications.

The SIM800C,32Mbit operates as a complete GSM/GPRS modem module. Key subsystems include: (1) RF Front-End – a quad-band GSM transceiver covering 850/900/1800/1900MHz; the RF section includes a power amplifier (PA), low-noise amplifier (LNA), mixer, and frequency synthesizer; the PA delivers up to +33dBm (2W) at 850/900MHz and +30dBm (1W) at 1800/1900MHz; the antenna connection is via a 50-ohm pad on the LGA package; (2) Baseband Processor – an integrated DSP and ARM processor handles GSM protocol stack (Layer 1-3), GPRS protocol, voice codec (EFR/FR/HR/AMR), and AT command processing; the baseband also controls the module’s GPIO, ADC, and other peripherals; (3) 32Mbit Serial Flash – a 4MB SPI NOR Flash connected to the baseband processor; the Flash stores the firmware (approximately 1.5MB), AT command file system (accessible via AT+FS commands), and OTA update staging area; the additional 16Mbit vs. the standard SIM800C provides more room for firmware updates and data logging; (4) Power Management – an integrated PMIC that generates all internal supply rails from the 3.4-4.4V input; the PMIC includes a buck converter for the digital core and LDOs for the analog and RF sections; the VBAT supply must be capable of delivering 2A peak current with less than 400mV droop during GSM transmit bursts; (5) UART Interface – the primary communication interface supporting AT commands at 1200-115200bps; the UART supports hardware flow control (RTS/CTS) to prevent data loss; a second UART (UART2) is available for debug output or GPS NMEA data input.

• IoT data logger: 32Mbit Flash stores sensor data locally when GSM coverage is unavailable, GPRS transmits in batch when coverage returns; 4MB stores weeks of sensor data
• Vehicle tracker: GPS NMEA data fed to UART2, GSM data session sends position to server, 32Mbit Flash stores track history for later upload
• Remote meter reading: power-up periodically, read utility meter via GPIO/ADC, log to Flash, transmit via GPRS, sleep at 0.7mA between readings