Embedded Systems Cellular Firmware Development(GSM)

Compare popular wireless solutions including Bluetooth classic, Wi‑Fi direct, NFC, Bluetooth Low Energy, Zigbee, 6LoWPAN, cellular GSM and LTE, and LoRa and LoRa One for IoT applications.

Learn how cellular technology solves spectrum limits through frequency reuse, building cells and allocating frequencies, with GSM basics like 25 megahertz, 125 channels, and hand over.

Explore full duplex transmission and its two duplex schemes—frequency division duplex and time division duplex—and learn how FEMA, TDMA, and CDMA manage access to prevent collisions.

Compare analog and digital cellular technology, noting analog modulation and no encryption versus digital encryption and TDMA/CDMA/FDM, and outline 1G–5G standards such as GSM, CDMA One, CDMA2000, UMTS, LTE, NR.

Trace the evolution from 1g to 5g, noting analog 1g, digital 2g–5g, and technologies like fdm, tdma, cdma, wcdma, and ofdm, setting the stage for GSM architecture.

Explore the GSM architecture, including the radio access network and core network. Understand how SIM, IMEI, and IMSI identifiers enable mobility, authentication, and security across GSM subsystems.

Develop a debug uart driver to enable microcontroller communication with the gsm chip and the pc serial port, covering clocks, gpio alternate function setup, and baud rate.

Develop the debug uart driver by enabling clock access for gpio port e and configuring pins 2 and 3 to alternate function AF7 for uart.

Develop a debug uart driver by enabling apb1 clock for the uart, enable rx/tx in cr1, and compute baud from the peripheral clock (115200) using a 16 megahertz system clock.

Implement a UART transmit function that waits for the transmit data register to be empty by polling the status bit seven. Retarget printf via _io_putchar so entire sentences transmit.

Develop a uart driver to connect the stm32 microcontroller with the A6 gsm module by configuring apb, gpio clocks, and p9/p10 alternate functions. Implement initialization, transfer direction, and tx/rx handling.

Develop a SysTick timer driver on Cortex-M4 microcontrollers to create millisecond delays by configuring the system timer, enabling internal clock, and polling the count flag.

Explore the first-in-first-out fifo to manage data packets between producers and consumers, using fifo put and fifo get, with a keyboard-to-word example.

Develop a dual fifo data structure for communication, implementing a transmission and reception fifo with init, put, get, and size functions, and full and empty checks.

Test the five four FIFO by loading and retrieving data, verify wrap-around, and address 8-bit data type limits; confirm TX and RX FIFOs before GSM data transmission.

Copy data from the transmit FIFO to the UART by implementing a transfer function that waits for the tx data register to be empty, then writes characters to the UART.

Implement a static output character function and a lowercase converter, then search the rx data stream for responses with a wait-for-response routine activated by interrupts.

Enable receive interrupts on the A6 UART, implement an interrupt handler with a callback to process incoming data, then read, debug print, and send commands to the GSM chip.

Learn to initialize the A6 GSM module, enable uart and debugging, and implement a test command that waits for an ok response.

Learn to run and extend GSM command tests to check signal quality, retrieve the module name, and verify network registration, with build and run steps on an STM32 board.

Develop a function to send sms messages by configuring text mode, composing the recipient number with country code, and issuing the required gsm commands.

Develop an outgoing call function using call control commands, construct the full number with country code, send the command, and handle the okay or error responses during testing.

Learn to drop a GSM call by issuing the drop call command, handle disconnects, and validate the response in embedded firmware, including timing delays to account for network latency.

Receive SMS messages from a GSM module by configuring the format to text and relying on interrupt-driven reception. Parse the incoming message to extract the sender, date, time, and text.

Learn to process received SMS in the RX stream by buffering, detecting the word 'message', and extracting the SMS data including phone number, date, time, and text for hardware actions.

Develop hardware modules by initializing peripherals on the microcontroller, build LCD, ATC, and pushbutton drivers, and turn on the LCD via an SMS while testing the GSM-driven workflow.

Build and test a push button driver for an embedded GSM system by configuring PC13 as an input, enabling GPIO clocks, and implementing a boolean get_button_state for an active-low button.

Develop an adc driver by configuring GPIO pin one as an analog input, enabling clocks, setting the ADC module and conversion sequence, and enabling the ADC for channel one.

Develop the adc read function by enabling continuous conversion, starting the adc, waiting for end-of-conversion, and reading the 12-bit data register, with testing on pin p1.

Explore the real time clock (RTC) architecture, including backup and main power domains, backup registers, alarms, wakeups, timestamp, tamper detection, and the calendar with BCD encoding.

Develop the RTC initialization function by enabling power and backup domains, selecting LSI as clock source, enabling RTC, and configuring the time format and async/sync prescalers with proper write-protection handling.

Develop the rtc alarm initialization function by disabling right protection, entering initialization mode, setting date and time, configuring and enabling the alarm and its interrupt, then exiting initialization mode.

Enable rtc alarm initialization by disabling write protection, entering initialization mode, and configuring date, time, and alarm registers via bit shifts, masks, and bcd fields, including pm vs 24-hour format.

Develops the RTC alarm initialization by masking the alarm register with mask bits to ignore the weekday, and enables the alarm in the control register.

Clear the RTC alarm flag in the ESR, define the alarm bit, configure line 17 for rising edge, enable the alarm interrupt in the VIC, then exit initialization.

Learn to test the RTC by reading date and time from registers, convert between BCD and binary, and handle alarm interrupts to display time on a console.

Learn to control hardware from SMS using esims by initializing the A6 module, clearing SMS storage, and parsing commands like LCD on/off to trigger hardware actions.

Learn to trigger hardware from a phone call by detecting ring in the data buffer, setting a notification flag, and turning on an LCD or other devices.

Use a push button as a hardware trigger to send an sms, configure the button state, and send a message to a designated number when pressed, illustrating a tamper-detection scenario.

Learn to trigger sms alerts from an rtc alarm by reading sensor data with the adc and sending it to an admin phone number, using a message and sms function.

Send sensor data as SMS periodically using the rtc, triggering every minute by comparing previous and current rtc minutes, with gsm initialization preceding rtc setup.