Digits
Digits is an open source RP2040/RP2350 PCB design by justinlindh: a 2-layer, 61.9 × 76.2 mm board with 74 components (42 distinct parts). It is built around the DRV8871DDAR, RP2040, W25Q16JVSSIQ, AMS1117-3.3 and more. Filed under retro computing.
Encrypted retro phone network — private VoIP over vintage desk phones
Carrier board that sits under a Raspberry Pi Zero 2 W inside a gutted vintage desk phone. Takes +5 V in, derives +3.3 V (U5 AMS1117) and +1.8 V (U7 XC6206) for the audio codec, and boosts +5 V up to ~37 V on-board (U10 XL6019) to drive the mechanical bell through the DRV8871 H-bridge. Hosts the TLV320AIC3104 codec for handset mic + earpiece and an RP2040 that runs keypad scanning, hook sense, and bell ringer. A single DPDT cradle switch (SW1) handles both hook sense and series mic-kill.
Built around
Parts list
74 components, 42 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | DRV8871DDAR | SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm | U2 |
| 1 | RP2040 | QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm | U3 |
| 1 | W25Q16JVSSIQ | SOIC-8_5.3x5.3mm_P1.27mm | U4 |
| 1 | AMS1117-3.3 | SOT-223-3_TabPin2 | U5 |
| 1 | TLV320AIC3104IRHBR | Texas_RHB0032E_VQFN-32-1EP_5x5mm_P0.5mm_EP3.45x3.45mm | U6 |
| 1 | XC6206P182MR | SOT-23 | U7 |
| 1 | XL6019E1 | TO-263-5_L10.2-W9.9-P1.70-LS14.4-TL | U10 |
| 1 | ABM8-272-T3 | Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | CONN_01X04 Conn_01x04 | JST_ZH_B4B-ZR-SM4-TF_1x04-1MP_P1.50mm_Vertical | J8 |
| 1 | SCREW_TERMINAL_01X02 Screw_Terminal_01x02 | JST_ZH_B2B-ZR-SM4-TF_1x02-1MP_P1.50mm_Vertical | BELL1 |
| 1 | 1.5A | Fuse_1210_3225Metric | F1 |
| 1 | CONN_01X07 Conn_01x07 | JST_ZH_B7B-ZR-SM4-TF_1x07-1MP_P1.50mm_Vertical | KEYPAD1 |
| 1 | Conn_02x20_Odd_Even | PinHeader_2x20_P2.54mm_Vertical | PI_ZERO_W1 |
| 1 | C158012 VIN_BARREL_PIGTAIL | JST_XH_B2B-XH-A_1x02_P2.50mm_Vertical | PWR1 |
| 1 | Hook_DPDT | SW_DPDT_Hook_24.2x17.1mm | SW1 |
| 1 | SW_Push | SW_PUSH_6mm | SW2 |
| 1 | CONN_01X02 Conn_01x02 | JST_ZH_B2B-ZR-SM4-TF_1x02-1MP_P1.50mm_Vertical | LED1 |
| 1 | C2286 LED_RED | LED_0603_1608Metric | D2 |
| 1 | C2289 LED_GREEN | LED_0603_1608Metric | D3 |
| 1 | SS56 | SMA_L4.3-W2.6-LS5.2-RD | D10 |
Show 22 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | 47UH 47uH | IND-SMD_L12.3-W12.3 | L10 |
| 1 | 470UF 470uF | CP_Elec_10x10.5 | C1 |
| 2 | 100NF 100nF | C_0805_2012Metric | C3, C4 |
| 2 | 15PF 15pF | C_0402_1005Metric | C5, C6 |
| 2 | 10UF 10uF | C_0603_1608Metric | C9, C11 |
| 4 | 1UF 1uF | C_0402_1005Metric | C10, C31, C39, C44 |
| 24 | 100NF 100nF | C_0402_1005Metric | C12, C13, C14, C15, C16, C28, C29, C30 +16 |
| 2 | 10UF 10uF | C_0402_1005Metric | C37, C45 |
| 2 | 0.47UF 0.47uF | C_0402_1005Metric | C46, C47 |
| 1 | 1NF 1nF | C_0402_1005Metric | C53 |
| 1 | 10UF 10uF | CP_Elec_5x5.3 | C55 |
| 1 | 100UF 100uF | CAP-SMD_BD10.0-L10.3-W10.3-FD | C100 |
| 1 | 1UF 1uF | C_0805_2012Metric | C101 |
| 1 | 220 | R_0805_2012Metric | R1 |
| 1 | 33K 33k | R_0402_1005Metric | R2 |
| 2 | 10K 10k | R_0402_1005Metric | R5, R11 |
| 1 | 1k | R_0402_1005Metric | R9 |
| 1 | 2.2K 2.2k | R_0402_1005Metric | R10 |
| 1 | 300 | R_0402_1005Metric | R12 |
| 1 | 120 | R_0402_1005Metric | R13 |
| 1 | 57.6K 57.6k | R_0402_1005Metric | R20 |
| 1 | 2k | R_0402_1005Metric | R21 |
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