stm32g4xx_usb_cdc

This repo contains a STM32G474 USB CDC example implementation, combined with Jan Breuer's SCPI parser library v2 allowing you to build your own STM32G4xx based scientific instruments.

The STM will present a Serial device, running the SCPI parser.

A query speed test can be performed by running testscripts/speedtest.py, performances up to 70ms/100 requests have been seen.

Working example instruments

Lucys Wireless Charging SMU

Jana Maries Mini-TDR

Folder structure

• usb_cdc_g4/ : Universal CDC implementation for STM32G4xx, include this folder + changes to the Makefile
• libscpi/ : Jan Breuer's awesome SCPI parser library v2
• Inc/ : Contains the header files, please note Inc/scpi-def.h
• Src/ : Contains the source files, please note Src/scpi-def.c and Src/scpi-com.c
• testscripts/ : Contains some python test scripts and example software

How to use the CDC-library for your own project

• Copy usb_cdc_g4/ and its contents to your project folder.

• Add the following lines to your Makefile.

C_SOURCES += \
usb_cdc_g4/STM32_USB_Device_Library/Class/CDC/Src/usbd_cdc.c \
usb_cdc_g4/STM32_USB_Device_Library/Core/Src/usbd_core.c \
usb_cdc_g4/STM32_USB_Device_Library/Core/Src/usbd_ctlreq.c \
usb_cdc_g4/STM32_USB_Device_Library/Core/Src/usbd_ioreq.c \
Drivers/STM32G4xx_HAL_Driver/Src/stm32g4xx_hal_pcd.c \
Drivers/STM32G4xx_HAL_Driver/Src/stm32g4xx_hal_pcd_ex.c \
Drivers/STM32G4xx_HAL_Driver/Src/stm32g4xx_ll_usb.c \
usb_cdc_g4/Src/usbd_cdc_if.c \
usb_cdc_g4/Src/usb_device.c \
usb_cdc_g4/Src/usbd_conf.c \
usb_cdc_g4/Src/usbd_it.c \
usb_cdc_g4/Src/usbd_desc.c

C_INCLUDES +=  \
-Iusb_cdc_g4/STM32_USB_Device_Library/Class/CDC/Inc \
-Iusb_cdc_g4/STM32_USB_Device_Library/Core/Inc \
-Iusb_cdc_g4/Inc

• Add the following to your global variables if needed.

extern uint8_t UserRxBufferFS[APP_RX_DATA_SIZE];
extern uint8_t UserTxBufferFS[APP_TX_DATA_SIZE];
extern uint8_t is_new_data_ready;
extern uint16_t new_data_length;

• Call the USB init

MX_USB_PCD_Init();
MX_USB_Device_Init();

• Received Data is present within main.c though the earlier added global variables, e.g.:

if (is_new_data_ready) {
  SCPI_Input(&scpi_context, UserRxBufferFS, new_data_length);
  is_new_data_ready = 0;
}

• Data can be transmitted via:

CDC_Transmit_FS(data, length);