| # USBTMC |
| |
| A USB Test & Measurement Class (USBTMC) instrument with USB488/SCPI support, behaving like a simple programmable instrument. |
| |
| ## What it does |
| |
| - Implements a USBTMC interface with USB488 capabilities and advertises SCPI support. |
| - Responds to `*IDN?` with an identification string (`TinyUSB,ModelNumber,SerialNumber,FirmwareVer123456`). |
| - Buffers other written messages and echoes them back as the query response, after a configurable delay. |
| - A `delay <ms>` command adjusts that simulated response delay (0–10000 ms). |
| - Maintains an IEEE-488.2 status byte (MAV/SRQ), and handles trigger, clear, and bulk abort requests. |
| - Supports the USBTMC indicator-pulse request, which briefly pulses the board LED. |
| - Uses an interrupt endpoint in addition to the bulk IN/OUT endpoints. |
| |
| ## USB Descriptors |
| |
| | Interface | Class driver | |
| |-----------|--------------| |
| | 0 | USBTMC | |
| |
| ## Configuration |
| |
| Notable `tusb_config.h` settings: |
| |
| ```c |
| #define CFG_TUD_USBTMC 1 |
| #define CFG_TUD_USBTMC_ENABLE_INT_EP 1 |
| #define CFG_TUD_USBTMC_ENABLE_488 1 |
| ``` |
| |
| ## Building |
| |
| CMake: |
| |
| ```bash |
| mkdir build && cd build |
| cmake -DBOARD=raspberry_pi_pico .. |
| cmake --build . |
| ``` |
| |
| Make: |
| |
| ```bash |
| make BOARD=raspberry_pi_pico all |
| ``` |
| |
| ## Try it |
| |
| The device appears as a USBTMC test-and-measurement instrument. Talk to it with a VISA/SCPI tool (for example PyVISA). The included `visaQuery.py` opens the instrument and sends `*IDN?`: |
| |
| ```bash |
| python visaQuery.py |
| ``` |
