Blackpants
About the Blackpants PCB
Blackpants is an open source STM32 PCB design by o7-machinehum, published on GitHub under the MIT license. It is a 6-layer board measuring 90 × 153 mm, with 285 components from 91 distinct parts.
Its main chip is the STM32F042C6U6, from the STM32 family. Other key parts include the USB2514BI-AEZG-TR, MIC2026-1YM-TR, USBLC6-2SC6, AOZ1280CI and TPSGM7227YUWQ10G. By type, the board carries 159 capacitors, 69 resistors, 17 ICs, 13 diodes, 12 inductors and 7 connectors.
It belongs with the wearables designs in this gallery.
From the project
Open blackpants.kicadpro** for the active A523 schematic and PCB. It replaces the A33 hierarchy and uses AXP717C + AXP323 with 2GB LPDDR4.
Open blackpants.kicadpro** for the active A523 schematic and PCB. It replaces the A33 hierarchy and uses AXP717C + AXP323 with 2GB LPDDR4.
- Schematic review PDF - Capture status and interface mapping - Six-layer layout status and previews - RAM sourcing - Source documents
All 65 SoC-to-RAM signal paths are connected. There are 139 open connections overall. Routing remains incomplete; DDR timing and signal/power integrity have not been approved.
Main components on the Blackpants
Blackpants bill of materials (BOM)
285 components, 91 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | STM32F042C6U6 STM32F042C6Ux | QFN-48-1EP_7x7mm_P0.5mm_EP5.6x5.6mm | U1 |
| 1 | USB2514BI-AEZG-TR USB2514B_Bi | QFN-36-1EP_6x6mm_P0.5mm_EP3.7x3.7mm | U3 |
| 1 | MIC2026-1YM-TR MIC2026-1xM | SOIC-8_3.9x4.9mm_P1.27mm | U4 |
| 2 | USBLC6-2SC6 | SOT-23-6 | U5, U6 |
| 1 | AOZ1280CI | SOT-23-6 | U7 |
| 1 | TPSGM7227YUWQ10G | UQFN-10_1.4x1.8mm_P0.4mm | U11 |
| 2 | USBLC6-2SC6 | SOT-23-6 | U12, U101 |
| 1 | AP3032KTR-G1 AP3032 | SOT-23-6_Handsoldering | U15 |
| 1 | A523 | Allwinner_A523_FCCSP-522_15x15mm_P0.5mm | U201 |
| 1 | NT6AN512T32AV-J2 | FBGA-200_10x15mm_P0.8x0.65mm | U301 |
| 1 | AXP717C | QFN-52-1EP_6x6mm_P0.4mm_EP4.6x4.6mm | U501 |
| 1 | AXP323 | QFN-20-1EP_3x3mm_P0.4mm_EP1.65x1.65mm | U502 |
| 1 | RTL8723DS | RTL8723 | U701 |
| 1 | AP3036BKTR-G1 AP3036B | SOT-23-6 | U801 |
| 1 | TPS61230DRCR | Texas_S-PVSON-N10_ThermalVias | U901 |
| 1 | CS325S24000000ABJT 24Mhz | Crystal_SMD_Citizen_CS325S-4Pin_3.2x2.5mm | Y1 |
| 1 | 24MHz / CL20pF / 20ppm | Crystal_SMD_3225-4Pin_3.2x2.5mm | Y201 |
| 2 | USB1046-GF-0190-L-B-A USB_A | USB_A_Receptacle_GCT_1 | J4, J5 |
| 1 | USB-C / charge + keyboard | USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J8 |
| 1 | USB-C / recovery | USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal | J101 |
Show 71 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | microSD / boot | microSD_HC_Hirose_DM3AT-SF-PEJM5 | J105 |
| 1 | Antenna | SMA_Amphenol_901-143_Horizontal | J701 |
| 1 | FH12-20S-0.5SH(55) Conn_01x20_MountingPin | Hirose_FH12-20S-0.5SH_1x20-1MP_P0.50mm_Horizontal | J801 |
| 1 | Protected 18650 / 1S Li-ion | BH-18650-B1BA002 | BT1 |
| 1 | 4A hold | Fuse_1812_4532Metric | F1 |
| 1 | Power | SW_PTS847MM160LSMTR2_LFS | PWR_BUTTON1 |
| 1 | KSC741JLFS SW_Push | SW_Push_1P1T_NO_CK_KSC7xxJ | SW1 |
| 1 | FEL | SW_SPST_TL3342 | SW101 |
| 1 | 10k @25C / cell-attached NTC | SolderWire-0.5sqmm_1x02_P4.6mm_D0.9mm_OD2.1mm | TH901 |
| 2 | KT-0603R LED | LED_0603_1608Metric | D6, D8 |
| 1 | 1N5819WS | D_SOD-323 | D13 |
| 8 | LTW-010DCG LED | LTW-010DCG | D15, D16, D17, D18, D19, D20, D21, D22 |
| 1 | MSS2P3 | D_MicroSMP_LargeCathode | D901 |
| 1 | Charge status | LED_0603_1608Metric | D902 |
| 1 | IFSC1515AHER6R8M01 6.8uH | L_Vishay_IFSC-1515AH_4x4x1.8mm | L3 |
| 7 | XAL4020-102MEB 1uH | L_Coilcraft_XAL4020-XXX | L501, L502, L503, L504, L505, L506, L507 |
| 1 | 120R @100MHz / >=0.6A | L_0603_1608Metric | L701 |
| 1 | CBC3225T220MR 22uH | L_1210_3225Metric | L801 |
| 1 | XAL4020-102MEB 1uH / Isat >= 7A | L_Coilcraft_XAL4020-XXX | L901 |
| 1 | 2.2uH / Isat >= 2A | L_Coilcraft_XAL4020-XXX | L902 |
| 13 | CL05B104KB54PNC 100nF | C_0402_1005Metric | C6, C8, C9, C10, C11, C13, C14, C15 +5 |
| 3 | CL05B105KQ5NQNC 1uF | C_0402_1005Metric | C7, C30, C44 |
| 1 | CC0402MRX5R5BB475 4.7uF | C_0402_1005Metric | C12 |
| 2 | GRM1555C1H100FA01D 10pF | C_0402_1005Metric | C28, C29 |
| 1 | CL10A106MA8NRNC 10uF | C_0603_1608Metric | C32 |
| 11 | 100nF | C_0402_1005Metric | C102, C121, C309, C318, C401, C507, C510, C704 +3 |
| 8 | 22uF | C_0603_1608Metric | C103, C502, C503, C504, C514, C515, C516, C922 |
| 50 | 2.2uF | C_0402_1005Metric | C201, C206, C207, C210, C211, C212, C222, C223 +42 |
| 20 | 100nF | C_0201_0603Metric | C202, C204, C209, C226, C245, C254, C255, C257 +12 |
| 12 | 1uF | C_0402_1005Metric | C203, C224, C234, C508, C509, C511, C512, C513 +4 |
| 7 | 22uF | C_0402_1005Metric | C205, C208, C220, C221, C230, C231, C240 |
| 2 | 18pF | C_0402_1005Metric | C250, C251 |
| 3 | 1nF | C_0402_1005Metric | C258, C259, C260 |
| 1 | 10uF | C_0402_1005Metric | C262 |
| 4 | 470nF | C_0402_1005Metric | C273, C274, C275, C276 |
| 8 | 10uF | C_0603_1608Metric | C310, C501, C505, C543, C544, C545, C703, C920 |
| 2 | 4.7uF | C_0402_1005Metric | C506, C517 |
| 2 | DNP | C_0402_1005Metric | C701, C702 |
| 1 | CL05A105KO5NNNC 1uF | C_0402_1005Metric | C801 |
| 1 | CC0603KRX7R7BB224 0.22uF | C_0603_1608Metric | C802 |
| 3 | 10nF | C_0402_1005Metric | C902, C911, C921 |
| 4 | 22uF | C_0805_2012Metric | C910, C912, C913, C914 |
| 3 | 0402WGF1001TCE 1k | R_0402_1005Metric | R2, R19, R33 |
| 3 | RC0402FR-135K1L 5.1K | R_0402_1005Metric | R3, R4, R10 |
| 1 | RC0402FR-131ML 1M | R_0402_1005Metric | R5 |
| 8 | RC0402FR-13100KL 100K | R_0402_1005Metric | R6, R7, R9, R13, R22, R26, R27, R28 |
| 1 | RC0402FR-1312KL 12K | R_0402_1005Metric | R8 |
| 1 | 0402WGF470KTCE 4R7 | R_0402_1005Metric | R23 |
| 4 | 10k | R_0402_1005Metric | R103, R503, R504, R715 |
| 10 | 100k | R_0402_1005Metric | R104, R105, R106, R107, R108, R123, R716, R717 +2 |
| 2 | 5.1k | R_0402_1005Metric | R121, R122 |
| 2 | 150k | R_0402_1005Metric | R124, R906 |
| 2 | 0 | R_0402_1005Metric | R201, R703 |
| 2 | 33 | R_0402_1005Metric | R203, R208 |
| 4 | 1k | R_0402_1005Metric | R204, R205, R901, R902 |
| 2 | 47k | R_0402_1005Metric | R206, R207 |
| 2 | 200 / 1% | R_0402_1005Metric | R209, R210 |
| 2 | 10k / 1% | R_0402_1005Metric | R211, R213 |
| 1 | 3.9k / 1% | R_0402_1005Metric | R212 |
| 1 | 2.7k / 1% | R_0402_1005Metric | R214 |
| 1 | 120 / 1% | R_0402_1005Metric | R301 |
| 1 | 240 / 1% | R_0402_1005Metric | R302 |
| 3 | 2.2k | R_0402_1005Metric | R501, R502, R907 |
| 5 | 10k | R_0201_0603Metric | R710, R711, R712, R713, R714 |
| 1 | RC0402JR-0710KL 10k | R_0402_1005Metric | R801 |
| 1 | RC0402JR-075R1L 5R1 | R_0402_1005Metric | R802 |
| 2 | 470 | R_0402_1005Metric | R903, R904 |
| 1 | 402k / 1% | R_0402_1005Metric | R910 |
| 1 | 100k / 1% | R_0402_1005Metric | R911 |
| 1 | 49.9k / 1% | R_0402_1005Metric | R920 |
| 1 | 15.8k / 1% | R_0402_1005Metric | R921 |
Blackpants design files
The KiCad project lives in the o7-machinehum/Blackpants repository on GitHub; these links point at the commit this page was built from.
Blackpants: common questions
What microcontroller does the Blackpants use?
The Blackpants is built around the STM32F042C6U6, from the STM32 family.
How big is the Blackpants PCB?
The Blackpants measures 90 × 153 mm, has 6 copper layers and is 1.6 mm thick.
How many components are on the Blackpants?
285 components, from 91 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 Blackpants design files?
From the o7-machinehum/Blackpants 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 Blackpants design in my own project?
Yes, under the terms of its MIT license, which o7-machinehum chose for the repository.
Can I test firmware for the Blackpants 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.
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