brake_torque_sensor¶
Subsystem sheet /brake_torque_sensor of mouse-joystick-pcb, from the board recipe subsystems/brake_torque_sensor.subsystem.yaml.
The brake and torque subsystem: the RTS-5 torque bridge front end with its 10 V excitation and ADS8689 ADC on SPI1, the 12 V regulator that feeds the bridge excitation from the 36 V rail, and the DAC80501-programmed 0 to 48.78 mA current sink that drives the magnetic particle brake.
Board note: board-authored sheet, 6 parts
Notes¶
- The torque bridge's analog monitor leaves on J901 (TQ_AOUT, a BNC) as a bench signal; it does not reach the MCU, torque arrives digitally over SPI1.
- The pulls are the board's (layout convention 10): R904 (10 k to +3.3V) holds TQ_CONVST_CS high so the ADC is idle until firmware frames a conversion; R901, R902, R903 and R905 (10 k to GND) define ~{BRAKE_FAULT}, TQ_SPI_SCK, TQ_SPI_COPI and TQ_CAL_EN while the bus switch is open, so neither the torque ADC nor the fault input floats at reset.
- The 12 V regulator is the adjustable TPSM365R6 family's 12 V configuration; its PGOOD is PG_12V for the MCU to read before trusting the bridge.
- The brake sink's fault is ~{BRAKE_FAULT} (open drain, pulled low here); its current readback is BRAKE_ISENSE on GP27 (ADC1).
Ports¶
The recipe's ports as the sheet symbol carries them, the root label each meets, and the net's class, MCU pin and meaning.
| Port | Shape | Wired to | Net | Class | GPIO | Meaning | |
|---|---|---|---|---|---|---|---|
+3.3V |
passive | shared | +3.3V_SW |
/+3.3V_SW |
PWR_3V3 | ||
+5V |
passive | shared | +5V_SW |
/+5V_SW |
PWR_5V | ||
+36V |
passive | shared | +36V_SW |
/+36V_SW |
PWR_HV_BUS | ||
BRAKE_ISENSE |
output | BRAKE_ISENSE |
/BRAKE_ISENSE |
MCU_FINE | GP27 |
Brake sink current readback, ADC1¹¹; in as the MCU sees it | |
DAC_SCL |
input | DAC_SCL |
/DAC_SCL |
Default | GP17 |
I2C0 SCL — same bus⁷; out as the MCU sees it, via the bus switch | |
DAC_SDA |
bidirectional | DAC_SDA |
/DAC_SDA |
Default | GP16 |
I2C0 SDA — analog 0x48, brake 0x49⁷; bidi as the MCU sees it, via the bus switch | |
GND |
passive | shared | GND |
/GND |
PWR_RETURN_LOCAL | ||
PG_12V |
output | PG_12V |
/PG_12V |
Default | |||
TQ_AOUT_MON |
output | open: no-connect flag | |||||
TQ_CAL_EN |
input | TQ_CAL_EN |
/TQ_CAL_EN |
Default | GP18 |
Torque calibration enable⁷; out as the MCU sees it, via the bus switch | |
TQ_CAL_EN_INST |
input | TQ_CAL_EN_INST |
/TQ_CAL_EN_INST |
INSTRUMENT | |||
TQ_CONVST_CS |
input | TQ_CONVST_CS |
/TQ_CONVST_CS |
Default | GP15 |
ADS8689 convert-start / frame, plain GPIO⁷; out as the MCU sees it, via the bus switch | |
TQ_CONVST_CS_INST |
output | TQ_CONVST_CS_INST |
/TQ_CONVST_CS_INST |
INSTRUMENT | |||
TQ_SPI_CIPO |
output | TQ_SPI_CIPO |
/TQ_SPI_CIPO |
Default | GP12 |
Torque ADC SPI CIPO (SPI1 RX)⁷; in as the MCU sees it, via the bus switch |
|
TQ_SPI_CIPO_INST |
output | TQ_SPI_CIPO_INST |
/TQ_SPI_CIPO_INST |
INSTRUMENT | |||
TQ_SPI_COPI |
input | TQ_SPI_COPI |
/TQ_SPI_COPI |
Default | GP11 |
Torque ADC SPI COPI (SPI1 TX)⁷; out as the MCU sees it, via the bus switch |
|
TQ_SPI_COPI_INST |
output | TQ_SPI_COPI_INST |
/TQ_SPI_COPI_INST |
INSTRUMENT | |||
TQ_SPI_SCK |
input | TQ_SPI_SCK |
/TQ_SPI_SCK |
Default | GP10 |
Torque ADC SPI clock (SPI1 SCK)⁷; out as the MCU sees it, via the bus switch |
|
TQ_SPI_SCK_INST |
output | TQ_SPI_SCK_INST |
/TQ_SPI_SCK_INST |
INSTRUMENT | |||
~{BRAKE_FAULT} |
output | ~{BRAKE_FAULT} |
/~{BRAKE_FAULT} |
Default | GP13 |
Brake block fault, active low⁷; in as the MCU sees it, via the bus switch | |
~{BRAKE_FAULT}_INST |
output | ~{BRAKE_FAULT}_INST |
/~{BRAKE_FAULT}_INST |
INSTRUMENT |
Blocks¶
The recipe's roles and the placements that fill them on this board.
| Role | Instance | Block | Lifecycle | Summary |
|---|---|---|---|---|
torque_bridge_0_3v3_ina821 |
torque_bridge_0_3v3_ina821 |
orb_weaver_private:torque_bridge_0_3v3_ina821 |
routed | RTS-5 bridge front end: 10 V excitation, INA821 gain 191.734, filtered full-scale ADC path and separate half-scale analog output. |
hv_to_12v_tpsm365r6 |
hv_to_12v_tpsm365r6 |
orb_weaver_tpsm365r6_adjustable:tpsm365r6_adjustable_12v |
routed | High-voltage input to an adjustable 12 V or 7 V rail: TI TPSM365R6F 600 mA buck module, one family source with the FB top leg, the PGOOD bottom leg and the second output capacitor as the variant. |
brake_current_sink_0_49ma_dac80501 |
brake_current_sink_0_49ma_dac80501 |
orb_weaver_private:brake_current_sink_0_49ma_dac80501 |
routed | DAC-programmed linear constant-current sink delivering 0-48.78 mA into a 24 V magnetic particle brake coil from a 36 V rail: a DAC80501ZDGSR at 3.3 V on I2C feeding a 0.19512 precision divider, an OPA197 integrating error amplifier on a ferrite-filtered 12 V rail driving a BUK7D36-60EX pass device over a 10 ohm Kelvin shunt, a second OPA197 as an independent 56.4 mA current ceiling that clamps the gate through a Schottky, a third as a 0-1.006 V ground-referenced current monitor behind a /2 output divider, an SN74LVC2G17 buffering the ceiling event out as active-low ~{BRAKE_FAULT}, and an S115Q flyback across the in-block 2-position 3.5 mm vertical coil terminal. |
Glue¶
The subsystem's own parts and nets, drawn by the board around the blocks.
| References | Part | Value | Role |
|---|---|---|---|
J901 |
OW-CONN-HL-BNC-KHDA |
Conn_Coaxial_HL-BNC-KHDA | |
R901, R902, R903, R904, R905 |
OW-RES-10K-0402 |
10k | pullup-pulldown |
| Net | Kind | Pins | Meaning |
|---|---|---|---|
+3.3V |
port | R904.1 |
|
GND |
port | J901.2, R901.2, R902.2, R903.2, R905.2 |
|
TQ_CAL_EN |
port | R905.1 |
|
TQ_CONVST_CS |
port | R904.2 |
|
TQ_SPI_COPI |
port | R903.1 |
|
TQ_SPI_SCK |
port | R902.1 |
|
~{BRAKE_FAULT} |
port | R901.1 |
|
TQ_AOUT |
label | J901.1 |