USMU
About the USMU PCB
USMU is an open source STM32 PCB design by joeltroughton, published on GitHub under the CERN-OHL-P-2.0 license. It is a 4-layer board measuring 70 × 43 mm, with 119 components from 41 distinct parts.
Its main chip is the STM32F072CBU6, from the STM32 family. Other key parts include the ADS1115IDGSR, GS8331, TS321AILT, USBLC6-2SC6 and ME6212C33M5G. By type, the board carries 45 capacitors, 44 resistors, 14 ICs, 6 diodes, 4 jumpers and 3 connectors.
It belongs with the power & battery designs in this gallery, and the repository also holds 1 earlier revision of it.
From the project
Credit card-sized, USB-powered 4 quadrant source-measure unit hardware and firmware
μSMU is a small source-measure unit designed for the very low-cost electrical characterisation of photovoltaic cells.
Want to buy a pre-assembled and calibrated μSMU with USB and test leads? Grab one from Tindie or Undalogic.
SMUs are "4-quadrant" devices, meaning they can both source and sink current at both positive and negative voltages. This makes them very useful for semiconductor device characterisation - including LEDs, transistors and solar cells.
Main components on the USMU
USMU bill of materials (BOM)
119 components, 41 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | ADS1115IDGSR ADS1115IDGS Texas Instruments | TSSOP-10_3x3mm_P0.5mm | U1 |
| 3 | GS8331 Gainsil | SOT-23-5 | U2, U7, U9 |
| 1 | STM32F072CBU6 STM32F072C8Ux ST Microelectronics | QFN-48-1EP_7x7mm_P0.5mm_EP5.6x5.6mm | U3 |
| 1 | TS321AILT TS321 ST Microelectronics | SOT-23-5 | U4 |
| 1 | USBLC6-2SC6 ST Microelectronics | SOT-23-6 | U5 |
| 1 | ME6212C33M5G Microne | SOT-23-5 | U6 |
| 1 | MCP1501T-40E/CHY MCP1501T-40E_CHY Microchip | SOT-23-6 | U8 |
| 1 | LT1970 Analog Devices | Linear_FE_TSSOP20 | U10 |
| 1 | DAC8571IDGKR Texas Instruments | VSSOP-8_3.0x3.0mm_P0.65mm | U11 |
| 1 | TPS65131RGET Texas Instruments | VQFN-24-1EP_4x4mm_P0.5mm_EP2.45x2.45mm_ThermalVias | U12 |
| 1 | H7650-45PR Shanghai Siproin Microelectronics | SOT-89-3 | U13 |
| 1 | PGA281AIPWR PGA281 Texas Instruments | TSSOP-16_4.4x5mm_P0.65mm | U14 |
| 1 | AO3401A BORN | SOT-23 | Q1 |
| 1 | 20021121-00010C4LF SWD Amphenol ICC | PinHeader_2x05_P1.27mm_Vertical_SMD | J1 |
| 1 | TYPE-C-31-M-12 USB_C_Receptacle_USB2.0 Korean Hroparts Electronics | TYPE-C-31-M-12 | J2 |
| 1 | 1-1634624-0 DUT TE Connectivity | BNC_Amphenol_B6252HB-NPP3G-50_Horizontal | J3 |
| 4 | SolderJumper_2_Open | SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1, JP2, JP3, JP4 |
| 1 | E6C0606RGBC3UDA Status LED EKINGLUX | E6C0606RGBC3UDA | D1 |
| 1 | E6C0606RGBC3UDA LED EKINGLUX | E6C0606RGBC3UDA | D2 |
| 2 | E6C0606RGBC3UDA LED_Small EKINGLUX | E6C0606RGBC3UDA | D3, D4 |
Show 21 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 2 | B5819W Microdiode Electronics | D_SOD-123 | D5, D6 |
| 2 | CBC3225T4R7MR 4.7uH Taiyo Yuden | L_Taiyo-Yuden_MD-3030 | L1, L2 |
| 19 | CL10B105KA8NNNC 1uF Samsung Electro-Mechanics | C_0603_1608Metric | C1, C5, C8, C9, C10, C11, C13, C15 +11 |
| 5 | CL10B104KB8NNNC 0.1uF Samsung Electro-Mechanics | C_0603_1608Metric | C2, C7, C16, C28, C36 |
| 6 | CL10B103KB8NNNC 10nF Samsung Electro-Mechanics | C_0603_1608Metric | C3, C14, C25, C40, C41, C43 |
| 5 | CL21A106KAYNNNE 10uF Samsung Electro-Mechanics | C_0805_2012Metric | C4, C6, C12, C27, C30 |
| 1 | CL10C201JB8NNNC 200pF Samsung Electro-Mechanics | C_0603_1608Metric | C21 |
| 2 | CL21A226MAQNNNE 22uF Samsung Electro-Mechanics | C_0805_2012Metric | C26, C32 |
| 1 | CL10B104KB8NNNC 200nF Samsung Electro-Mechanics | C_0603_1608Metric | C29 |
| 2 | CL10C020BB8NNNC 2pF Samsung Electro-Mechanics | C_0603_1608Metric | C31, C34 |
| 2 | DNP | C_0805_2012Metric | C39, C45 |
| 2 | CL10B102KB8NNNC 1nF Samsung Electro-Mechanics | C_0603_1608Metric | C42, C44 |
| 15 | ERJPB3D1002V 10k Panasonic | R_0603_1608Metric | R1, R2, R9, R11, R12, R17, R18, R20 +7 |
| 7 | ERJ3RBD1001V 1k Panasonic | R_0603_1608Metric | R3, R4, R5, R7, R23, R25, R28 |
| 2 | ERJ3EKF5101V 5.1k Panasonic | R_0603_1608Metric | R6, R16 |
| 8 | ERJPB3D1003V 10k Panasonic | R_0603_1608Metric | R8, R10, R13, R15, R19, R27, R30, R31 |
| 2 | ERJ3EKF3303V 330k Panasonic | R_0603_1608Metric | R14, R36 |
| 3 | ERJPA3F4702V 47k Panasonic | R_0603_1608Metric | R33, R34, R35 |
| 5 | ERJ3EKF1000V 100 Panasonic | R_0603_1608Metric | R37, R38, R42, R43, R44 |
| 1 | ERA3AEB49R9V 50 Panasonic | R_0603_1608Metric | R40 |
| 1 | ERJUP3D10R0V 10 Panasonic | R_0603_1608Metric | R41 |
USMU design files
The KiCad project lives in the joeltroughton/uSMU repository on GitHub; these links point at the commit this page was built from.
USMU: common questions
What microcontroller does the USMU use?
The USMU is built around the STM32F072CBU6, from the STM32 family.
How big is the USMU PCB?
The USMU measures 70 × 43 mm, has 4 copper layers and is 1.6 mm thick.
How many components are on the USMU?
119 components, from 41 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the USMU design files?
From the joeltroughton/uSMU repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the USMU design in my own project?
Yes, under the terms of its CERN-OHL-P-2.0 license, which joeltroughton chose for the repository.
Can I test firmware for the USMU without the hardware?
Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug STM32 firmware against it before you order a PCB.
Earlier revisions in the repo: uSMU_v05
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