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FT232H USB GPIO Interface

Adafruit page PCB files

FT232H

The FT232H breakout is used as a GPIO output interface when running the temperature control loop on a Windows workstation.

In this setup, temperature is measured using a National Instruments NI-9211 thermocouple module, which requires the control software to run on Windows with NI drivers.

Since Windows machines do not provide native GPIO, a USB-GPIO bridge is required to drive the heater control hardware.

For this purpose the system uses an Adafruit FT232H breakout.

Role in the control loop

The FT232H is used to generate the heater control signal.

Typical signal chain:

flowchart TD

subgraph Measurement
    TC["Thermocouple"]
    NI["NI-9211"]
end

subgraph Software
    WIN["Windows"]
    PY["TemperatureControl (Python)"]
end

subgraph Actuation
    FT["FT232H GPIO"]
    SSR["SSR"]
    H["Heater"]
end

TC --> NI
NI --> WIN
WIN --> PY
PY --> FT
FT --> SSR
SSR --> H

classDef sensor fill:#243322,stroke:#6ce3a1
classDef software fill:#1e2a3a,stroke:#6cb3ff
classDef actuator fill:#3a2a1e,stroke:#ffb86c

class TC,NI sensor
class WIN,PY software
class FT,SSR,H actuator

TemperatureControl NI9211.py ft232h.py

Notes

The FT232H is mainly used as a simple GPIO bridge for heater control.

While this architecture introduces several layers:

NI → USB → Windows → Python → FT232H → SSR → heater

it provides reliable thermocouple measurements using the NI-9211 isolated input hardware.

Future work may include building a dedicated isolated thermocouple acquisition board to remove the NI dependency.