General purpose analog/digital FrontEnd Controller, running on NUCLEO-G431KB board.

Development, control, monitoring and data transfer of STM32 MCU boards.

Development platform: STM32CubeIDE.
Development language: C++.
Development host OS: linux.
Connection to host, power and debugging are all through a USB2 link. Typical power consumption: 1 Watt.
Communication with host: through linux serial port /dev/ttyACM, with bit rate 10 Mbaud.
The software archictecture is similar to ADO or EPICS. Board holds Process Variables (PVs) similar to ADO parameters and responds to following requests: info, get and set.
The transmitted data are binary packets with 4-byte header and arbitrary payload. The streamed ADC packets have binary pyloads, the communication packes have payloads with JSON-packed text.
Typical source code size is 3-10 KB.
Remote restart using usbreset command.

Implemented on a NUCLEO G431KB evaluation board. The board configuration and pin assignment could be found here.

Eight of 12-bit ADC channels, sampling rate is up to ~3 Msps, range: 0 to 3.3V.
One Arbitrary Waveform Generator (WFG), also working as DAC: 12-bit, up to 2 Msps.
One Gate Delay Generator (GDG), 32-bit, resolution 6 ns.
One Pulse Width Modulation (Pulser), 16-bit, resolution 6 ns.
Eight digital GPIO, some of them could be configured as serial interfaces (RS232, Modbus, RS485, SPI, I2C).
CPU: ARM Cortex-M4, 32bit, 170 MHz.
ART Accelerator, FPU, DSP, DSP performance: 0.3 ms for 1024 point FFT.
Interrupt reaction time: ~500 ns, deterministic.

Dependencies

PyQt5-5.15.1+ for stmscope.py
STM32CubeIDE v1.14.0

Build from scratch.

Building a minimal C code

Start STM32CubeIDE
Click File/New/STM32 Project
Click Board Selector
Select NUCLEO-G431KB
Enter in Project Name: stm32genscope, in Targeted Language: C++, click: Finish.
Click Project/Generate Code. You may be asked to update firmware.
Add the following code in main.c after /* USER CODE END WHILE */:

HAL_GPIO_TogglePin(GPIOB,GPIO_PIN_8);
HAL_Delay(1000);

Click Run/Debug.
Click F8. The green LED should blink at 0.5 Hz.

Converting to C++

In Project explorer: rename Core/Src/main.c to Core/Src/main.cpp
Make sure you have the following code in main.cpp after /* USER CODE END WHILE */:

HAL_GPIO_TogglePin(GPIOB,GPIO_PIN_8);
HAL_Delay(500);

In Project Explorer: click Convert to C++
Click: Project/Clean. It should re-build everything and end up with
Click: Run/Debug.
Click: F8. The green LED should blink at 1 Hz.

Add user code for stm32genscope

Replace following project files with corresponding files from the git repository:

./stm32genscope.ioc
./Core/Src/main.cpp
./Core/Inc/stm32genscope.h

Click: Project/Generate code. It will produce ./Core/Src/main.c, which need to be removed as it will shadow our ./Core/Src/main.cpp
In Project Explorer: delete ./Core/Src/main.c.
Click: Project/Clean. It should re-build everything and it should not be errors in Console
Click: Run/Debug.
Click: F8 to run the board in debugging mode.

Quick Test

Connect Pulser Output TIM4_CH1 (PA11) to TrigADC input TIM1_CH1 (PA8). Connect WFG output (PA5) to ADC1 input (PA0).
Connect NUCLEO-G431KB to a USB port.
Start stmscope.py:

$python3 python/stmscope.py -n -q -g

The stmscope.py accepts the following text commands from terminal:

- info          # list of all supported PVs.
- info pv       # info on a particular PV.
- get pv        # get value object of a PV.
- set pv value  # set PV value.
- up arrow      # repeat last command.

Several commands can be combined together using semicolon (;) as separator:

>info; get version; info adc_sampletime

Check, if board is alive:

>info	# It should print list of device parameters. You can use info with parameter name to inquire on specific parameter, i.e. `info version`.
{'PVs': ['version', 'debug', 'fec', 'sleep', 'pulser_width', 'pulser_period', 'pulser_prescaler', 'pulser_fire', 'pulser_inverted', 'gdg_trig', 'gdg_front', 'gdg_tail', 'gdg_inverted', 'nADC', 'adc_reclen', 'adc_srate', 'adc_delay', 'adc_trig', 'adc_prescaler', 'adc_sampletime', 'wfg_shape', 'wfg_level', 'wfg_step', 'wfg_trig', 'trig_level']}

Communication with the board

>get version
{'version': {'MCU': 'STM32G431', 'soft': 'v1.0.4 2023-12-31', 'clock': 170000000, 'baudrate': 7372800}}
>get adc_srate        # to correct time axis of the plot, just in case.
>set adc_trig auto

Fig. 1. No signals, ADC is auto triggering.

>set wfg_trig auto; set wfg_shape triangle

Fig. 2. WFG is generating triangle waveform on ADC1, auto-triggering.

>set adc_trig ADC1P

Fig. 3. ADC is triggered on positive edge of ADC1. Trigger level is default, 2000.

#>set trig_level 100 #does not work
>set trig_level 3000
>set adc_trig ADC1N

Fig. 4. Trigger level changed to 3000, ADC is triggering on negative edge of ADC1.

set adc_trig ExtP
set pulser_fire 0
set wfg_trig pulser

Fig. 5. ADC is triggered on positive edge of an external trigger, pulser provides the external trigger.

>set wfg_step 1; set adc_sampletime 2; set adc_prescaler 4 #

*Fig. 6. WFG sampling period set to 1 us, ADC set to fastest sampling rate.

Generate constant level on WFG Output (Pin PA5):

>set wfg_trig off
>set wfg_shape flat
>set wfg_level 2000

Troubleshooting

Restart MCUFEC

Find the USB bus number and device number using command lsusb, then:

sudo usbreset /dev/bus/usb/bus#/device#

ASukhanov / stm32genscope