Specifications - The-Hybrid-Atelier/RheoBoard GitHub Wiki

Figures on this page are already written on Parts to buy, the assembly instructions, Parts to 3D print, and the firmware reference.

System

From the assembly instructions:

This simple rheometer is a pneumatic retraction-extrusion system with 2 air pumps + 1 valve on a flat 3D-printed panel, driven by an ESP32 over BLE and sensed by a Qwiic MicroPressure sensor.

The sensing routine runs a REP (retraction-extrusion pulse) on command and streams a pressure trace.

Basic soldering is not required if the boards already have headers and the actuator leads are prepared.

Panel

From Parts to 3D print:

• Material: PLA, printed on a Bambu Lab printer with the normal profile
• Parts: base_panel.STEP, about 170 × 170 × 4 mm with 4 mm holes; pump_holder.STEP, about 42.5 × 45 × 81 mm; and valve_bracket.STEP, the small bracket (sizes approximate, from the STEP geometry).
• Placement is the annotated panel photo. The annotated panel file in the repository is BuildYourOwn/cad/encloser/panel-annotated.pdf. The readable labels are in Step 01 of the assembly instructions.

Fasteners are 4 mm zip ties. A count is not stated. The files stay in encloser.

Component sizes, from the bill of materials and the component datasheets:

• Pumps: Adafruit 4699 / ZR370-02PM, 58.2 × Ø27.0 mm nominal
• VALVE2: Adafruit 4663 / FA0520E, 36.02 × 14.5 mm top-view envelope
• ATtiny1616 seesaw: 25.5 × 17.8 mm
• ESP32 Thing Plus WRL-15663: 64.77 × 22.86 mm
• SparkFun MPRLS and Qwiic Button: 25.4 × 25.4 mm each
• L298N modules: generic module dimensions vary; check your exact boards

Bill of materials

Quantities, sources, and datasheets are on Parts to buy. Printed parts are on Parts to 3D print.

Pumps are rated ~4.5–5 V and the valve ~6 V. Adafruit's ~50% pump duty-cycle recommendation describes intermittent run time, not a 50% PWM ceiling; firmware may use brief higher-PWM pulses, but the pumps should not run continuously. That warning is on Safety.

Firmware

From the firmware reference. The sketch and BLE device name are 2P1V_Adafruit. Serial baud is 115200.

I2C addresses:

• Qwiic Button: 0x6F
• MicroPressure (MPRLS): 0x18
• ATtiny1616 seesaw: 0x49

Seesaw pin	Signal	Drives	Pin type
0	PUMP1_EN	L298N #1 ENA — vacuum pump	PWM
1	PUMP2_EN	L298N #1 ENB — pressure pump	PWM
4	VALVE1_EN	Reserved for L298N #2 ENA; physically NC	digital
5	VALVE2_EN	L298N #2 ENB — the only valve driven	digital

Qwiic button, from the firmware reference: 1-click = REP, 2-click = latched vacuum, hold = momentary pressure.

A REP runs BASELINE → RETRACT → EXTRUDE → RELAX in a fixed 1200 ms window (REP_TIME).

OSC address	Default
rheo/sense/rate	10 ms, clamped to 10–1000 ms
rheo/rep/pull/power	54 (%)
rheo/rep/pull/time	315 ms, clamped to 1–5000 ms
rheo/rep/push/power	100 (%)
rheo/rep/push/time	345 ms, clamped to 1–5000 ms
rheo/rep/push/ramp/start	40 (%)
rheo/rep/push/ramp/time	300 ms; 0 disables the ramp
rheo/rep/baseline/time	420 ms
rheo/rep/interval	500 ms

The extrude drive ramps from push/ramp/start to push/power over push/ramp/time, then holds at push/power for the remainder of push/time.

OSC address descriptions, serial commands, and the phase diagram are in the firmware reference.