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