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STM32F103, STM32F407 · level reference · 11 min read
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38. Consolidated project catalog

Everything in the handbook marked with the 🔧 icon, in one list. Each item is a finished thing: you can build it on a breadboard, flash it and see the result. For each one you will find what you need beyond the board, which peripherals are involved, how hard it is and what you will understand by doing it. The order follows the sections; the recommended sequence for a beginner is in 38.2.

Legend
● basic: one block, one evening
●● intermediate: two or three blocks, an understanding of timing
●●● advanced: the kernel or external chips, debugging is a must
B BluePill, STM32F103C8
D Discovery with the STM32F407: LEDs PD12…PD15, has a DAC; the Nucleo-F401 has its LED on PA5 and no DAC
G Nucleo with the STM32G474 — for the analog blocks and HRTIM

Terms used in the documentation

Term Meaning
debug probe a debug adapter (ST-Link, J-Link)
logic analyzer a logic analyzer
operational amplifier (op-amp, OPAMP) an operational amplifier
shunt resistor a shunt, a low-value resistor in the current path
shift register a shift register
multiplexer (mux) a multiplexer, a "selector switch"
EEPROM electrically erasable read-only memory
flyback / freewheeling diode a suppression (reverse) diode

38.1 Catalog

The core and system mechanisms

§ Project Hardware beyond the board Blocks Difficulty What you will understand
7.6 A button on an interrupt a button, a resistor EXTI, NVIC, GPIO ● the "peripheral → EXTI → NVIC" chain, clearing the flag, bounce
8.4 Blinking an LED nothing: PC13 on B, PD12 on D GPIO, RCC ● the port clock, the CRL/MODER registers, BSRR versus ODR
8.5 Polling a button a button GPIO ● pull-up, the active level, debouncing by time
9.5 UART transmission through DMA a USB–UART adapter DMA, USART ●● the buffer, DMAT, the difference between "handed over" and "sent out"
9.7 An LED breathes without the processor an LED with a resistor on B; not needed on D — PD12 TIM, DMA ●● DMA writes to a register of another timer, the pace comes from a second timer, circular mode, working in sleep
11.5 Writing to the internal Flash nothing FLASH, RCC ●● unlocking, erasing a page, writing by half-words, where to store settings
11.8 Settings in Flash as a log nothing; a "save" button if you like FLASH ●● writing records in a row without needless erases, a sequence number and CRC-32, surviving a power loss, the layout version

Peripherals

§ Project Hardware beyond the board Blocks Difficulty What you will understand
13.5 PWM an LED or a servo TIM, GPIO ● PSC/ARR/CCR, the doubling on APB1, MOE on TIM1
13.10 LED brightness from an encoder a mechanical encoder, an LED with a resistor TIM, GPIO ●● encoder mode ×4, the input filter, the difference of readings across zero, a gamma-corrected scale
14.4 A single ADC measurement a potentiometer ADC ● sampling time, calibration on the F1, the pin's analog mode
14.6 ADC scanning with DMA two or three sensors ADC, DMA ●● scan mode, a ring buffer, volatile on DMA data
14.9 Supply voltage and temperature without external parts nothing ADC ● VREFINT, the factory codes of the F4, integer conversion, the longest sampling time
15.4 A table-driven signal generator D (the BluePill and the F401 have no DAC); an oscilloscope or an earphone with a resistor DAC, DMA, TIM ●● a table of samples, triggering by a timer, frequency = clock / (points × period)
15.6 An electronic load D (the BluePill and the F401 have no DAC); an op-amp, a MOSFET on a heatsink, a 1 Ω shunt DAC ●●● the DAC sets the current through the op-amp loop, the DAC buffer is off, the power heats the transistor
16.3 UART transmission a USB–UART adapter USART ● TXE versus TC, the baud rate divider, a terminal
16.5 Receiving variable-length packets a USB–UART adapter USART, DMA ●● detecting the IDLE gap, a ring buffer, ORE
16.8 A Modbus RTU slave a USB–UART adapter or an RS-485 transceiver; the master on a computer USART, TIM, GPIO ●● an 11-bit character, end of frame by a 3.5-character gap, exceptions, the transmitter by TC
17.4 Reading a sensor register over I²C any sensor with I²C I²C ●● start — address — register — restart — read; ADDR and both SR
17.6 Reviving a stuck I²C bus a sensor with I²C I²C, GPIO ●● nine clocks by hand, why the slave holds SDA
17.8 An external AT24C EEPROM a 24C04 or 24C08 chip I²C ●● page writes, polling for readiness, the upper bits of the cell address in the device address
18.5 Exchanging a block over SPI any chip with SPI SPI ● CPOL/CPHA, BSY before releasing CS, full duplex
18.9 The JEDEC flash memory identifier an SPI Flash chip SPI ● command 0x9F, skipping the first response, 0xFF and 0x00 as signs of a broken connection
18.11 A chain of 74HC595 shift registers two or three 74HC595 chips, LEDs SPI, GPIO ● the byte order in the chain, latching after BSY
20.7 Virtual COM port: receiving commands a USB cable; on B — a 1.5 kΩ pull-up on D+ USB ●● a packet is not a string, a ring between the interrupt and the loop, character-by-character input, USBD_BUSY when transmitting
21.9 Measuring time: the cycle counter and an ITM channel a debugger that receives SWO DWT, ITM ● CYCCNT, a separate channel for numbers, the 0x0B packet and a word
22.4 WS2812B addressable LEDs a strip or several LEDs, a 5 V supply TIM, DMA ●● PWM + DMA as a code generator, ±150 ns timing, GRB order
22.7 Display and keypad in one interrupt a four-digit display, two 74HC595, a 4×4 keypad, digit transistors TIM, SPI, GPIO ●● multiplexed display at 250 Hz per digit, rows as open-drain, 20 ms debouncing

FreeRTOS

§ Project Hardware beyond the board Blocks Difficulty What you will understand
26.4 A periodic task: two versions an LED kernel ●● vTaskDelay versus xTaskDelayUntil, period drift in numbers
26.9 Who gets the CPU nothing kernel, run-time accounting ●● time slicing, starvation, waiting gives time to lower priorities, priority cut after configASSERT
27.7 Button → queue → LED a button, an LED kernel, queue ● the queue timeout as a timer, bounce, sending without waiting and counting losses
29.5 One handler for a group of timers three LEDs kernel timers ●● the timer ID, the daemon, zero wait in a callback
29.6 A link watchdog timer a USB–UART adapter kernel timers, USART ●● a one-shot timer restarted from an interrupt, FromISR
29.7 A device watchdog on a software timer nothing kernel timers, event group, IWDG ●● the daemon is always alive, task check-ins in an event group, read-and-clear in one call
30.8 The gatekeeper task a USB–UART adapter kernel, queue ●●● a resource without a mutex, requests from interrupts, no deadlocks
31.5 Inputs and outputs by mask four buttons, four LEDs kernel, event group ●● "all" and "any", a change flag instead of waiting for a mask, the rule changes on the fly

External memory and files

§ Project Hardware beyond the board Blocks Difficulty What you will understand
41.5 W25Q128FV: reading and writing an SPI Flash chip SPI ●● JEDEC ID, Write Enable, erasing before writing, BUSY
41.6 AT45DB161E: a non-standard chip a chip with a buffered architecture SPI ●●● how a "different" flash differs: buffers, a page size of 528, reading the status
42.5 Working with files through FatFS an SD card or SPI Flash SPI, FatFS ●●● the disk layer, f_mount/f_open/f_write/f_sync, what breaks when power is switched off

Analog, power and control

§ Project Hardware beyond the board Blocks Difficulty What you will understand
44.8 Overcurrent protection inside the chip G; a 10 mΩ shunt, a switch, a load up to 10 A OPAMP, COMP, TIM, ADC ●●● shunt → amplifier ×16 → comparator → the timer's fault input: PWM shuts off without the program
46.3 A 12 → 5 V buck converter G or F334; a half-bridge with a driver, an inductor, a capacitor HRTIM ●●● 54 400 steps per 100 kHz period, a complementary pair with dead time, the fault input
47.6 A controller in code a 10 ms RC circuit or a heater with a sensor TIM, ADC ●● a constant period, a limit on the integrator, the derivative on the measurement

Electronics on a breadboard

§ Project Hardware beyond the board Blocks Difficulty What you will understand
49.3 A resistor for an LED an LED, a resistor GPIO ● the voltage budget: the drop across the pin, the resistor and the LED
50.5 PWM plus RC instead of a DAC a 10 kΩ resistor, a 1 µF capacitor TIM ● the average equals the duty cycle, with an 82.5 mV peak-to-peak sawtooth on top at 1 kHz
51.5 A transistor switch for a relay a transistor, a 12 V relay, a suppression diode, a 510 Ω resistor, a 12 V supply GPIO ●● a forced gain of 10…20, a base current of 5 mA, why the coil needs a diode
60.6 Expanding outputs with a shift register a shift register with a latch, eight LEDs GPIO or SPI ● three pins for any number of outputs, the latch, 4 µs for 32 outputs at 8 MHz
60.7 An analog multiplexer in front of the ADC an 8-channel analog multiplexer ADC, GPIO ●● the channel resistance adds to the source: 4.2 µs of sampling for 100 kΩ

The C language on the chip

§ Project Hardware beyond the board Blocks Difficulty What you will understand
76.3 A calibration table a sensor with a non-linear characteristic ADC, Flash ● a const table in Flash, binary search, integer interpolation

Communication

§ Project Hardware beyond the board Blocks Difficulty What you will understand
93.5 The LoRa SX1276 radio module an SX1276 module with an antenna; two for a link SPI, GPIO, EXTI ●● radio module registers: the LoRa bit in sleep, the frequency in 64 bits, flags cleared by writing ones

The 38.1 catalog by group: a cell is a project, the colour is its difficulty; 16 basic, 26 intermediate and 6 advanced, with the steps of the 38.2 order and the three projects not on the BluePill labelled

The 38.1 catalog matrix: a row is a project, a filled cell is a block from the "Blocks" column, difficulty on the left; at the bottom, how many projects exercise each block

38.2 Recommended order

For someone starting from scratch on a BluePill — sixteen steps, each building on the previous ones:

Step § Why now
1 8.4 the first firmware; make sure the "build → download → board" chain works
2 8.5 the first input and the first bounce
3 16.3 text output to a terminal — without it you have nothing to debug with later
4 13.5 the first timer, the first understanding of frequencies
5 7.6 the first interrupt; compare it with the polling from step 2
6 14.4 the first measurement; print it to the terminal from step 3
7 9.5 the first DMA on the already familiar UART
8 14.6 DMA on the ADC: two familiar blocks together
9 16.5 receiving is harder than transmitting; this is where buffers and IDLE appear
10 18.5 SPI is simpler than I²C, an easier way to start with buses
11 17.4 I²C with a real sensor
12 11.5 save the settings you have collected over ten steps
13 26.4 the first task under the kernel — on the already familiar LED
14 29.6 kernel timers on the already familiar UART
15 30.8 the gatekeeper: the kernel in earnest
16 42.5 files on a card — the crowning step: SPI, the kernel, external memory together

The sixteen steps of 38.2 as a snake: subsection numbers in order; the first twelve without the kernel, 13–15 FreeRTOS, the sixteenth files on a card

After the sixteenth step the rest of the catalog can be done in any order.

38.3 What you need

A minimal kit that covers the whole catalog:

What for
BluePill or Nucleo/Discovery everything; 15.4 and 15.6 only on the Discovery with the F407 (DAC)
an ST‑Link debugger (not a clone — if you need SWO) downloading, debugging, 21.9
a USB–UART adapter 9.5, 16.x, 29.6, 30.8
an RS-485 transceiver (optional) 16.8
a breadboard, wires, buttons, LEDs, resistors 7.6, 8.5, 9.7, 13.5, 26.4, 27.7, 29.5, 49.3
a potentiometer; for scanning — two or three potentiometers or sensors 14.4, 14.6
a mechanical encoder 13.10
a USB cable; on the BluePill — a 1.5 kΩ resistor on D+ 20.7
four buttons and four LEDs 31.5
an op-amp, a MOSFET on a heatsink, a 1 Ω shunt 15.6
any sensor with I²C 17.x
a 24C04 or 24C08 EEPROM chip 17.8
an SPI Flash chip 18.5, 18.9, 41.x
an SD card with an adapter 42.5
a WS2812B strip and a 5 V supply 22.4
a four-digit display, a 4×4 keypad, two 74HC595, digit transistors 22.7
an oscilloscope or a logic analyzer 15.4, 22.4, and desirable in general
a Nucleo board with the STM32G474 44.8, 46.3
a 10 mΩ shunt, a switch and a load up to 10 A; a half-bridge with a driver, an inductor, a capacitor 44.8, 46.3
a transistor, a 12 V relay, a suppression diode, a 12 V supply 51.5
a shift register, an analog multiplexer, resistors and capacitors 18.11, 47.6, 50.5, 60.6, 60.7
a sensor with a non-linear characteristic 76.3
two LoRa modules on the SX1276 with antennas 93.5

The oscilloscope is the only expensive item on the list, and you can do without it almost everywhere. But section 36 ends with the words "an oscilloscope on the line" for a reason: what is on the wire, not what should be there, is the answer to half of the "works sometimes" questions.

38.4 Summary

Next: section 38а "Interview questions: a hundred questions on the handbook with short answers and a section reference".

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