Here is a list of all documented files with brief descriptions:

[detail level 123]

core
inc
button.h	Button module public API
cbuf.h	Circular buffer module public API
cmd.h	Command subsystem public API
common.h	Common utility module public API
console.h	Console subsystem public API
datalog.h	Data log module public API
err.h	System-wide error code definitions
init.h	Common initialization public API
io.h	Digital IO module public API
log.h	Log subsystem public API
menu.h	Menu module public API
modules.h	System module identifier definitions
neo6.h	NEO-6M GPS module public API
sd.h	SD card driver public API
ssd1309.h	SSD1309 OLED display driver public API
src
button.c	Button module implementation file
cbuf.c	Circular buffer implementation
cmd.c	CMD subsystem implementation
common.c	A module that contains code common to all other modules
console.c	Console module implementation
datalog.c	Data log module implementation file. Implements the GPS data logging feature of the GPS device
init.c	Common initialization implementation file
io.c	This module implements a digital IO module
log.c	Log subsystem implementation
main.c	Application entry point for the GPS tracking device
menu.c	Menu implementation file
modules.c	System module name string table
neo6.c	NEO-6M GPS module implementation file
sd.c	SD card driver implementation file
ssd1309.c	SSD1309 display driver implementation file
syscalls.c	STM32CubeIDE Minimal System calls file
drivers
inc
arm_cortex_m4.h	Register definitions and bit position enumerations for the Arm Cortex-M4 core peripherals
arm_cortex_m4_nvic.h	Arm Cortex-M4 NVIC driver public API
arm_cortex_m4_systick.h	Arm Cortex-M4 SysTick driver public API
stm32f401re.h	STM32F401RE MCU-specific peripheral register definitions and bit position enumerations
stm32f401re_gpio.h	STM32F401RE GPIO driver public API
stm32f401re_i2c.h	STM32F401RE I2C driver public API
stm32f401re_rcc.h	STM32F401RE RCC driver public API
stm32f401re_rtc.h	STM32F401RE RTC driver public API
stm32f401re_spi.h	STM32F401RE SPI driver public API
stm32f401re_usart.h	STM32F401RE USART driver public API
src
arm_cortex_m4_nvic.c	Arm Cortex-M4 nested vectored interrupt controller implementation
arm_cortex_m4_systick.c	Arm Cortex-M4 SysTick driver implementation
stm32f401re_gpio.c	GPIO driver implementation for STM32F401RE
stm32f401re_i2c.c	I2C driver implementation for STM32F401RE
stm32f401re_rcc.c	RCC driver implementation for STM32F401RE
stm32f401re_rtc.c	RTC driver implementation
stm32f401re_spi.c	SPI driver implementation for STM32F401RE
stm32f401re_usart.c	USART driver implementation for STM32F401RE