PIC Microcontroller (Antminer)

The PIC microcontroller is a small Microchip chip — on the S19 generation, specifically a PIC16F1704 — found on many conventional Antminer hashboards from the S9 era through the S19 family. Its job is not hashing. It stores board-specific calibration data, gates power to the hashing domains, and answers the control board's questions during boot. Think of it as the hashboard's birth certificate, tuning sheet, and power switch packed into an eight-pin-class part — and one of the most consequential single components on the board when it fails.

What the PIC actually does

The PIC holds calibration parameters — the computing frequency and operating-voltage values determined for that specific board at the factory — and works alongside the board's EEPROM, which carries serial and identity data. On boot, the control board talks to the PIC over the I2C bus (pins 3 and 4 on the PIC16F1704) and uses what it learns to bring the board up at the correct operating point. Just as critically, the PIC participates in power enablement: it drives the MOS transistor switch that lets PSU voltage reach the boost converter feeding the voltage domains. Remember that voltage on these boards is regulated per domain — groups of chips sharing a supply stage — never per chip, and the PIC sits upstream of that whole chain. On the S19 the PIC is designated U3; on the S19 Pro it is U6.

Failure symptoms and bench diagnosis

A dead or corrupted PIC produces one of the classic hashboard presentations: the kernel log reports 0 chips found on the chain, because the domains never received power and the ASICs never enumerated. The bench check is direct: measure the PIC's output pin (U3 pin 2 on S19, U6 pin 2 on S19 Pro) and expect 3.3V; if it is absent, suspect PIC failure or programming corruption before condemning anything else on the board. The fix is equally direct — the PIC16F1704 can be re-flashed in place using a Microchip PICkit3 programmer, restoring the calibration image. A related trap: the hashboards installed in one miner must carry consistent stored data to be accepted, so mismatched or corrupted board data can stop an otherwise healthy machine from starting. Reading, comparing, and rewriting that data is standard repair workflow — see EEPROM (hashboard) for the companion component, and note that Bitmain also shipped certain S19j Pro variants in a noPIC configuration where this calibration scheme is handled differently.

The S21 has no PIC — full stop

This is worth stating explicitly because it is a constant source of confusion in repair forums: the S21 generation has no PIC chip. Bitmain removed the PIC entirely with the BM1368-generation boards (S21, T21, S21 Hydro), restructuring the power architecture around buck converters, LDOs, and additional level shifters, with board data carried in EEPROM. Diagnostic procedures written for S19-family boards that say "check the PIC" simply do not transfer to S21 hardware, and buying PIC programming gear for an S21 fleet is money spent on a chip that is not there. Know which architecture is on your bench before you reach for the PICkit.

Handling discipline matters here too: the PIC sits on the same exposed board edge as the connectors and is as vulnerable to ESD as anything else on the board — programming corruption from static or a botched flash is a documented failure cause, not folklore. Ground yourself, use a proper programming clip rather than held probes, and back up the existing PIC image before writing a new one, so a failed experiment is a five-minute restore instead of a dead board.

PIC-level work — verifying the 3.3V enable, re-flashing calibration, reconciling board data across chains — sits squarely in the board-level repair tier alongside test fixture diagnosis. If a board in your fleet shows the zero-chip signature and you would rather not tool up for it, D-Central's repair service handles PIC and EEPROM-level faults routinely.